Overview of Plant Life

© Jones & Bartlett Learning, LLC © Jones & BartlettOUTLINE Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Overview of • Concepts • Overview of Plant Structure Plant Life • Overview of Plant Metabolism © Jones & Bartlett Learning, LLC • Overview© of Jones Information & Bartlett in Plants Learning, LLC NOT FOR SALE OR DISTRIBUTION • OverviewNOT of Plant FOR Diversity SALE and OR DISTRIBUTION LEARNING OBJECTIVES Evolution After reading this chapter, students will be able to: • Overview of Plant Ecology • Describe the basic internal and external organization of plants. Box 2-1 Alternatives: Familiar Plants and • Compare© Jones plant & and Bartlett human Learning,metabolism. LLC © JonesSome & BartlettConfusing Learning, Look-Alikes LLC • ListNOT three FORsources SALE from whichOR DISTRIBUTION plants receive information. NOT BoxFOR 2-2 Alternatives:SALE OR Plants DISTRIBUTION Without • Define and give examples of haploid and diploid plants. Photosynthesis • Explain the concept of clades. Box 2-3 Plants and People: Toxic Compounds • Describe the interconnected dynamic between photosynthetic © Jones & organismsBartlett andLearning, organisms LLC that respire. © Jones & BartlettBox Learning, 2-4 Botany and LLC Beyond: Noah’s Flood NOT FOR SALE OR DISTRIBUTION NOT FOR SALE ORand DISTRIBUTION Population Biology

Did© JonesYou & Know? Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Chapter Opener Image: The life of each of these • Plants, as distinct from algae, have existed for more than plants has much in common with our own lives. Each 420 million years. started from a fertilized egg, grew into an adult by • Photosynthesis captures energy in sunlight and is almost the obtaining energy and nutrients, as well as defending only© sourceJones of & energy Bartlett for all Learning, life on Earth. LLC © Jonesitself & from Bartlett diseases and pests. Learning, Each inherited its LLC genes • ThereNOT are FOR almost SALE 297,000 OR species DISTRIBUTION of living plants and about NOT FORfrom its SALE parents and OR each will DISTRIBUTION make efforts to have sexual 1,260,000 species of animals. reproduction. Like us, these plants have gradually evolved such that they now differ from their ancient ancestors. • Plants are adapted to live everywhere on land in extraordinarily Also like us, each plant interacts with many other diverse conditions except where it is severely cold (under organisms, some of which help it, some of which harm it; © Jones & permanentBartlett Learning, snow and ice) LLC or dry (parts of the Sahara© Desert). Jones & Bartlett Learning,no plant lives in isolation LLC from all other organisms. • Plants defend themselves from herbivores with spines and poisons NOT FOR SALEbut simultaneously OR DISTRIBUTION provide food for animals that pollinateNOT them. FOR SALE OR DISTRIBUTION 19

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. ❚❚ Concepts © Jones Anyone& Bartlett reading Learning, this book isLLC probably familiar with ani-© Jones & Bartlett Learning, LLC NOT FORmal SALE life. We OR each DISTRIBUTION know quite a bit about our own body, ourNOT FOR SALE OR DISTRIBUTION organs, our metabolism, and the way in which we inherited DNA from our parents. We know that all humans are members of one extremely diverse species, Homo sapiens, a species in which individuals differ from each other in almost every possible character© such Jones as heigh &t, Bartlett athletic abi Learning,lity, intel- LLC © Jones & Bartlett Learning, LLC ligence, health, talent, interNOTests, FOR goals, SALEambitions, OR spir DISTRIBUTIONituality, NOT FOR SALE OR DISTRIBUTION and more. We know that we had ancient ancestors, hominids who preceded the first Homo sapiens, and we had ancient relatives such as Homo neanderthalensis (Neanderthal Man) and Homo habilis. These other members of Homo are extinct now, ©but Jones several &dist Bartlettant relatives Learning, such as chimpLLC anzees, © Jones & Bartlett Learning, LLC orangutans,NOT FORand gor SALEillas are ORpart DISTRIBUTIONof our evolutionary fam- NOT FOR SALE OR DISTRIBUTION ily. Most of us are probably not too familiar with our own ecology except that we are social animals (we live in cities and do things in groups), we consume a large part of Earth’s © Jones &resources, Bartlett and Learning, produce harmful LLC pollution. © Jones & Bartlett Learning, LLC Beyond our knowledge of our own biology, most of us NOT FORare SALE also familiar OR DISTRIBUTION with the biology of other animals such asNOT FOR SALE OR DISTRIBUTION dogs, cats, mosquitoes, bees, whales, and so on. Even if this is the first biology book you have ever read, you are almost certainly a knowledgeable biologist already. FIGURE 2-1 Shoot tip of cottonwood (Populus deltoides) in late autumn. It has a Your knowledge of© anima Jonesl biolog &y Bartlett is an excel lentLearning, foun- LLCcentral stem with 15 leaves attached (only ©the petiolesJones are visible & Bartlett in this close-up Learning, LLC dation for learning about plant biology. Plant life is based on view); each petiole attaches to the stem at a node. Five nodes each contain one all the same fundamentalNOT prin ciplesFOR tha SALEt underlie OR the DISTRIBUTION lives of prominent axillary bud, each covered with NOTprotective FORbud scales. SALE The very tip OR of the DISTRIBUTION animals, fungi, and all other living beings. Of course, plants shoot has a terminal bud. Bud scales protect the delicate cells at the center of each do many things differently, but let your knowledge of your bud; after surviving the winter, these five axillary buds will grow and produce many own biology guide your study of plant biology. And always small flowers. In springtime, the terminal bud will grow as a continuation of the shoot, producing more leaves, nodes, and internodes, making the branch longer. keep ©the Jones two fund &amental Bartlett quest Learning,ions in mind: LLCWhat are the © Jones & Bartlett Learning, LLC alternatives? What are the consequences of each alternative? NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION microscopically small. Leaves vary greatly in shape and tex- ❚❚ Overview of Plant Structure ture and in being evergreen or deciduous, but the important thing is that almost all stems bear leaves; they are a part of Think about the many types of plants you know. Trees, the fundamental pattern of plant bodies. Hornworts and © Jones &garden Bartlett flowers, Learning, grass, bulbs, LLC cacti, and vines for example.© Jonessome &liverworts Bartlett are Learning, plants that nev LLCer produce any kind of NOT FORTremendous SALE OR diver DISTRIBUTIONsity is present, but if we examine each ofNOT leafFOR at all SALE (see Chapter OR DISTRIBUTION 20 for more details). these, we find they all share the same pattern of body organi- Another aspect of the fundamental organization of plants is zation. With only a few exceptions, the body of every plant is that almost all plants have roots (FIGURE 2-5). In almost all plants, organized in the following simple way. roots are confined to one end of the stem, but it is also common Almost every plant consists of one or several stems, each of which has leav©es Jonesattached &at regioBartlettns cal ledLearning, nodes LLC © Jones & Bartlett Learning, LLC (FIGURE 2-1; TABLE 2-1). JustNOT above FOR the attSALEachment OR poin DISTRIBUTIONt is an NOT FOR SALE OR DISTRIBUTION axillary bud, some of which develop into branches whereas TABLE 2-1 The Organs that Compose Most Plants others develop into flowers, but many axillary buds remain Vegetative organs Roots dormant and never do anything. Stems are typically slender, less than 5 mm in diameter, but wide ones occur in cacti and Stems © Jones & Bartlett Learning, LLCFIGURE 2-2 © Jones & Bartlett Learning, LLC other desert plants that use them to store water ( ). Leaves SomeNOT stems FORare extrem SALEely sho ORrt, DISTRIBUTIONas in carrots and cabbage, NOT FOR SALE OR DISTRIBUTION but vines and bamboo typically have extremely long stems. Reproductive organs of flowers Sepals Leaves too are diverse. They range in size from the Petals gigantic leaves of palms to ones that are merely large, as in Philodendron, down to ones that are small, such as those of Stamens © Jones &rosemary Bartlett (FIGURES Learning, 2-3, 2-4). LLC Although cacti are often said© Jones & Bartlett Learning, LLC Carpels NOT FORto SALE be leafless, OR allDISTRIBUTION have tiny foliage leaves that are almosNOTt FOR SALE OR DISTRIBUTION 20 Chapter 2: Overview of Plant Life

FIGURE© 2- 2Jones Like many plants& Bartlett adapted to deserts, Learning, golden barrel cactus LLC (Echinocactus FIGURE 2-4 This© is Jones a very common & weed Bartlett in most gardens, Learning, and you may have LLC already grusoniiNOT) stores water FOR in very SALE broad stems ORcomposed DISTRIBUTION of thousands of water-filled cells. spent some timeNOT pulling it up.FOR It is in theSALE genus Chamaesyce OR DISTRIBUTION, and plants tend to grow Spines prevent animals from eating the cactus to obtain water. Because the stem is so flat against the ground, often with a circular form only a few centimeters in diameter. broad, it is exceptionally heavy, so succulent plants typically branch much less than These leaves are tiny, only about 1 mm across. The plant is covered in flowers, plants of non-succulent plants: This plant has only one stem, somewhat like the single stem of Chamaesyce bloom even while only a few weeks old; each flower here is emerging from a palm tree. The spines are highly modified bud scales (compare with the bud scales of an axillary bud. cottonwood in Fig. 2-1), so each spine cluster is an axillary bud. The leaf that makes the © Jones &axil forBartlett each spine cluster Learning, is microscopic and LLC cannot be seen here. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

to see roots emerge along a stem, such as in ivy that climbs on sporangia on their underside (FIGURES 2-8). Without turning fences and trees, attached to them by numerous groups of roots a leaf over to see if it has sporangia and spores, one would (FIGURE 2-6). Underground© stemJoness like &thos Bartlette of irises andLearning, ginger LLCnever guess that it is not just ©an Jonesordinary &leaf Bartlett. Reproductive Learning, LLC also produce roots along their length rather than at just one end structures are a bit more complex in the seed plants. Conifers (FIGURE 2-7). Roots are lessNOT varie dFOR than stem SALEs or leav ORes, andDISTRIBUTION most make seed cones and pollen cones,NOT ang FORiosperms SALE mak ORe flow DISTRIBUTION- roots are usually easy to recognize as roots. ers (FIGURES 2-9, 2-10). Only flowers will be discussed here in Roots, stems, and leaves are the vegetative organs of a this overview; details about conifers and ferns are presented plant. By that, we mean that they are responsible for obtain- in later chapters. ing energy© Jones and mat &erials Bartlett for gro wthLearning, and survival, LLC but they do Flowers© appear Jones to be & so Bartlett diverse it Learning,seems as if ther LLCe must not carry out sexual reproduction. When a plant is ready to be thousands of types. Just think of how diverse roses, irises, reproduce,NOT reproductive FOR SALE organs OR DISTRIBUTION develop. The reproductive lilies, snapdragons,NOT FOR and petuniSALEas areOR. But DISTRIBUTION here too there is organs of most ferns are barely distinguishable from vegeta- only one basic organizational plan, and once you know it, tive organs: They are basically just foliage leaves that produce you can easily understand almost any flower. Each flower is a

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 2-3 Like many palms, Bismarkia nobilis has gigantic leaves. Each petiole is FIGURE 2-5 These onions are whole plants, with roots at one end, the shoot at the more than 1 m long, and the giant leaf blades are both long and wide. An individual other. Onion leaves are a bit unusual because they are part of a shoot called a bulb: The palm usually has many fewer leaves than do other trees, but because each palm leaf purple portion of each leaf (the leaf base) is swollen and stores water and nutrients, the is so large, palms have as much total photosynthetic surface area as do many other green upper portion carries out photosynthesis. © Jones &plants. Bartlett For some unknown Learning, reason, many peopleLLC refer to the leaves of palms and ferns © Jones & Bartlett Learning, LLC NOT FORas SALE“fronds” even OR though DISTRIBUTION they are true leaves. NOT FOR SALE OR DISTRIBUTION Overview of Plant Structure 21

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones &Alternatives Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION BOX 2-1 Familiar Plants and Some Confusing Look-Alikes

Most of us have no tro©uble Jones recognizing & Bartlett a very lar Learning,ge num- LLC“Grass” is used correctly ©almos Jonest all the & time Bartlett but app Learning,lied LLC ber of plants, at least whileNOT the FORy are SALEin bloom OR or if DISTRIBUTION certain to the wrong groups sometimes.NOT LawFORn gras SALEses are OR gras DISTRIBUTIONs characteristic features are present. Apples, oranges, peaches, (except for clover), as are wheat, rye, barley, rice, corn, and and pears are fruits we all recognize, and if they are still on even giant bamboo (no, it is not a tree; it is a giant, very their trees, we have no trouble recognizing the whole plant tough grass). If you see a grass-like plant growing in standing as well (FIGURE B2-1A). Strawberries are very familiar, but you water, however, it is almost certainly a sedge and not a grass might© be Jones initially uncert& Bartlettain if you Learning, saw them gro LLCwing on the (FIGURE B2-1N© ).Jones Sedges &are Bartlett distinguished Learning, from gras LLCses by soil surface,NOT supFORported SALE by thin, OR delica DISTRIBUTIONte stems (such stems are feeling the stemsNOT and FOR remem SALEbering OR this DISTRIBUTIONmnemonic: “Sedges runners). Daisies (often called asters) are also usually easy to have edges, but grasses are round from tip to ground.” Using recognize because even though there are hundreds of spe- the wrong name is not a terrible problem; few of us know the cies, most all look like the one in FIGURE B2-1B. The same names of very many plants, and as we discuss plants with our is true for morning glories (FIGURE B2-1C), lilies, water lilies, friends, using exactly the right name is not often necessary. It © Jones &and Bartlett many others Learning, (FIGURE B2-1D LLC). © Jonesis like & using Bartlett the wor Learning,d “bug” for spider LLCs, insects, and various NOT FOR SALEIn contrast, OR DISTRIBUTION several groups of plants can cause confu-NOT otherFOR tiny SALE animals. OR DISTRIBUTION sion. Many people believe any plant that is succulent and There is a similar situation with the words we use for plant spiny is a cactus (FIGURE B2-1E), whether they are looking parts. You will often hear the word “frond” when people talk at an Agave (FIGURE B2-1F), a Yucca (FIGURE B2-1G), an Aloe about the leaves of palms or ferns. “Frond” is just fine, but it (FIGURE B2-1H), or one of the succulent spurges (“spurge” may is not a precisely defined term; it is just that for some reason, be an unfamiliar name ©and Jones refers to & memb Bartletters of Learning,the genus LLCsome people use it instead of ©the Jones word “leaf & ”Bartlett for palms Learning,and LLC Euphorbia [FIGURE B2-1INOT]). These FOR are allSALE succu lent,OR mostDISTRIBUTION are ferns. Similarly, “stalk” is notNOT a pre ciselyFOR defined SALE, tec ORhnical DISTRIBUTION spiny, and most live in deserts, but agaves and yuccas are term, and neither are “rind,” ”peel,” “skin,” and several others. much more closely related to lilies and irises than to cacti Just keep in mind that some precise botanical terms such as (their long, thick leaves are extreme versions of lily leaves). “stem” and “leaf” are the same as ordinary English words, Furthermore, although many botanists also mistakenly call and some like “epidermis” are identical to the terms used by spurges© cacti,Jones the &spur Bartlettges are in Learning,a completely differenLLC t fam- zoologists, ©even Jones though & a plaBartlettnt epidermi Learning,s is completely LLC dif- ily andNOT are most FORly natSALEive to ORAfrica, DISTRIBUTION whereas cacti are native ferent fromNOT an anima FORl epidermi SALEs. If OR you DISTRIBUTIONhave already studied to the Americas. I heard a person guess that a giant Agave a lot of zoology, be very careful as you come across botanical americana must be an Aloe vera: He made a really good guess words that are the same as zoological or medical words: The because the plants do look alike, even though that agave is meanings are probably very different. hundreds of times larger than an aloe. Plants have common names and scientific names, and © Jones & BartlettDoes it really Learning, matter if peo LLCple confuse these plants? Not© Jonesa great & dealBartlett of effor Learning,t is made to LLCensure that each species NOT FORreally, SALE because OR the DISTRIBUTIONy are correct that the plant is a large, suc-NOT ofFOR plant SALE or anima ORl orDISTRIBUTION any other organism has only one culent spiny desert plant. If it is important to have the correct scientific name. For some plants the name of the plant’s name, they can ask at a garden center or a botany department genus is the same as its common name; agaves are in the or perform a Google image search. genus Agave, and citruses are in the genus Citrus. When Other plants that are often confused with each other we write the common name, we do not capitalize or itali- are roses and camellias© Jones(the flower & sBartlett are quit eLearning, similar; LLCcize it, but we do if we are refer© Jonesring to the & scientBartlettific nam Learning,e LLC FIGURE B2-1J) and palmNOT trees, cycFORads, SALEand fern ORs (som DISTRIBUTIONe have of the genus: oranges, lemonNOTs, and FOR limes SALEare all citrORuses DISTRIBUTION similar shapes and leaves; in fact, in areas where cycads are in the genus Citrus. Lemons are Citrus limon, oranges are common, people often use cycad leaves instead of palm Citrus sinensis, and limes are Citrus latifolia. It is natural to leaves on Palm Sunday; FIGURE B2-1K). People often describe think of “limon” as the species name of lemons, but that is most aquatic plants as “moss,” but true mosses almost never not correct; the species name is Citrus limon. The scientific grow© in Joneswater: Lon &g Bartlettstringy ones Learning, that float are LLCusually algae; name of all© spe Jonescies alwa &ys Bartlett has two worLearning,ds: The first LLC is the thoseNOT with stemFORs, leavSALEes, and OR flower DISTRIBUTIONs are flowering plants; genus nameNOT and FORthe seco SALEnd is the OR spe DISTRIBUTIONcies epithet; there- and a few very small water plants are ferns. Many of us (even fore, the species name is the genus + species epithet. When professional botanists) use the word “moss” for any very tiny I mentioned agaves above I used the common name agave, plant whether it is a moss or just a small plant that resembles the genus name Agave, and the scientific name of the giant a moss (FIGURE B2-1L and FIGURE B2-1M). agave, Agave americana. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 22 Chapter 2: Overview of Plant Life

(G) © Jones & Bartlett Learning, LLC(H) © Jones & Bartlett(I) Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

(J) (K) (L) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

(M) (N) FIGURE B2-1 (A) An orange tree. (B) Daisies. (C) Morning glories. (D) Oxblood lilies. (E) All the tall or globe-shaped plants are cacti; those with thick gray, yellow, or green leaves are agaves. (F) Agave americana. (G) Yucca torreyi. (H) Aloes. I) A spurge (Euphorbia, not a cactus). (J) Camellia flower. (K) A cycad, often called a “sago palm.” (L) Selaginella peruviana © Jones &(despite Bartlett the species epithetLearning, this plant grows LLC in Texas, not Peru; not a moss). (M) A liverwort© Jones (Frullania inflata & ,Bartlett not a moss). (N) Learning, A sedge, not a grass. LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Overview of Plant Structure 23

(A) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

FIGURE 2-6 This is an old vine of poison ivy (Toxicodendron radicans), climbing up a tree trunk, attached to it by clusters of adventitious roots. These roots mostly just attach to the tree’s bark, and the poison ivy also has ordinary roots at the base of the vine that absorb water and nutrients. Even though© Jones this part of & the Bartlettpoison ivy plant Learning,is so old that LLC © Jones & Bartlett Learning, LLC it has shed its leaves, it is still extremelyNOT poisonous FOR and SALEshould not be OR handled. DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (B) FIGURE 2-8 (A) This is the upper surface of a leaf of sword fern (Polystichum reproductive shoot; that is, each flower has a short stem with munitum), and it carries out photosynthesis. But in many ferns, some leaves also leaf-like© Jonesstructures & att Bartlettached to it. Learning,Sepals protect LLCthe rest of the produce spores on© their Jones undersides, & and Bartlett it is necessary toLearning, turn the leaf over toLLC be certain. (B) This is the lower surface of a sword fern leaf, and it is involved in flowerNOT as it deveFORlops, SALE and peta ORls attDISTRIBUTIONract pollinators after the NOT FOR SALE OR DISTRIBUTION sepals spread apart allowing a flower to open. Above the pet- reproduction. Each of the round structures is called a sorus (plural: sori; pronounced als are stamens that produce pollen, followed by carpels that SOAR eye), a group of dozens of minute structures (sporangia) that each produce spores. Only some of the leaves of sword ferns have sporangia, other leaves would have nothing special when turned over.

© Jones & Bartlett Learning, LLC © Joneseach contain& Bartlett one or Learning,more ovules ( FIGURELLC 2-11). Stamens and NOT FOR SALE OR DISTRIBUTION NOT carpelsFOR SALEare essen ORtial bec DISTRIBUTIONause each pollen grain contains two sperm cells and each ovule contains an egg cell. Insects, birds, and wind carry pollen from stamens to carpels, usually from the stamens of one plant to the carpels of a different plant of the same species. After a sperm cell fertilizes an egg cell, an © Jones & Bartlett Learning, LLCembryo and the surrounding ©tis suesJones grow &to beBartlett a seed while Learning, LLC NOT FOR SALE OR DISTRIBUTIONat the same time some carpelNOT tissues FOR develop SALE into a fruiORt. InDISTRIBUTION angiosperms, all seeds develop inside a fruit—that is one of the defining characters of being an angiosperm (FIGURE 2-12). If flowers have this fundamental organization of sepals, petals, stamens, and carpels, how can there be so many types © Jones & Bartlett Learning, LLC of flowers?© And Jones especially & Bartlett so many Learning,flowers in which LLC this organization is not easy to see? One reason is that in many FIGURENOT 2-7 This FOR a rhizome SALE of ginger ( ZingiberOR officinaleDISTRIBUTION) that was purchased at a NOT FOR SALE OR DISTRIBUTION grocery store, planted for a few weeks, and then dug up for examination. By planting flowers, one or two of these organs are extremely underde- the rhizome, we activated it and stems grew upward; new adventitious roots spread in veloped or even absent completely. If a flower is pollinated all directions but would have soon turned downward. All new parts are white because by birds or insects, then having brightly colored petals helps plants cannot synthesize chlorophyll while in the dark. The new adventitious roots a flower to be noticed. But if pollen is carried by wind, then © Jones &emerge Bartlett from the new Learning, shoots: As each shoot LLC grows upward toward the light, it makes © Jonesit is a &waste Bartlett of resources Learning, to produce LLC petals: Wind-pollinated NOT FORits SALEown particular OR supply DISTRIBUTION of roots. NOT flowersFOR SALEoften lack OR peta DISTRIBUTIONls completely (FIGURES 2-13, 2-14). 24 Chapter 2: Overview of Plant Life

Ovary

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 2-11 Carpels consist of three parts: a stigma, a style, and an ovary. Within the ovary is one or several ovules, each of which contains an egg cell (only one ovule is shown here). If the carpel is pollinated and the egg is fertilized, the fertilized egg develops into an embryo, the rest of the ovule develops into a seed, and the ovary © Jones & Bartlett Learning, LLC © Jonesdevelops & into Bartlett a fruit. Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 2-9 This is a seed cone of a pine tree (Pinus). It was pollinated many months FIGURE 2-15 ago, and now the cone is growing larger as are the many seeds inside it. Tough, hard other ( ). Such fusions almost never occur among cells and sticky resin protect the seeds as they grow. When the seeds are mature, the leaves. We could go on listing flower modifications, but the cone will expand enough to cause the scales to separate and allow the seeds to fall out. important thing is that each and every type of flower, no mat- © Jones & Bartlett Learning, LLCter how exotic, is just a modification© Jones of one & basic Bartlett plan. Learning, LLC The internal organization of plants is even simpler and NOT FOR SALE OR DISTRIBUTIONmore uniform than the externNOTal for FORm (TABLE SALE 2-2). OR While DISTRIBUTION Similarly, certain plants produce clusters of tiny flowers and young, every part of a plant—every root, stem, leaf, petal, rather than making sepals for each flower, they just make one and all the rest—consists of an external epidermis, internal set of large bracts that protects the entire cluster; these flowers lack© sepals.Jones Sta &mens Bartlett and car pelsLearning, too can be LLCmissing from © Jones & Bartlett Learning, LLC the flowers of certain species. InNOT addition, FOR flower SALEs differ OR fro DISTRIBUTIONm each other because in NOT FOR SALE OR DISTRIBUTION some, the various organs are fused to each other whereas in other flowers, all organs remain separate and distinct. It is common to see all the sepals of a flower fused to each other such that they form a tube, and petals often fuse to each © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Carpel Stamen Petal © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

NOT FOR SALE OR DISTRIBUTIONSepal NOT FOR SALE OR DISTRIBUTION

FIGURE 2-12 A seed pod of coral bean (Erythrina herbacea) is a fruit similar to the © Jones &FIGURE Bartlett 2-10 This isLearning, a simplified, diagrammatic LLC representation of the four basic © Jonespod of a &bean Bartlett or pea: When it Learning, is ripe, it opens by twisting, LLC releasing the mature seeds. NOT FORorgans SALE of flowers. OR DISTRIBUTION NOT ThisFOR is a dry SALE fruit, in contrast OR to anDISTRIBUTION apple or tomato, which are fleshy fruits. Overview of Plant Structure 25

© Jones & Bartlett Learning, LLC FIGURE 2-15 In© this Jones flower of Datura & Bartlett wrightii, the five Learning, green sepals have fusedLLC to NOT FOR SALE OR DISTRIBUTION each other, makingNOT a tube, FORand the five SALE white petals OR have DISTRIBUTIONfused to each other, making a second tube. The tip of each petal remains separate and recognizable. The five stamens do not fuse to each other and are distinct. The five carpels have fused to each other, so only a single style and stigma are present.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT tissueFOR in SALE roots isOR cort DISTRIBUTIONex; in stems it is both pith and cortex; and in leaves and flowers it is referred to as mesophyll. Ground tissues of stems are easy to see in potato tubers: Each FIGURE 2-13 These are three clusters of ash (Fraxinus) flowers; ash is wind tuber is a short, wide stem that consists of very broad pith pollinated, so there is no need for large© Jones colorful petals & to Bartlettattract animal pollinators. Learning, LLCand a moderately wide cortex.© LeaJonesves of &Aloe Bartlett have a thick Learning, LLC Each of these three clusters consists almost entirely of anthers, the part of a stamen succulent ground tissue, the watery mesophyll. that produces pollen. NOT FOR SALE OR DISTRIBUTIONPlants have two distinctlyNOT differen FORt vascSALEular ORtissues. DISTRIBUTION Xylem (pronounced ZY lem) transports water and minerals upward from roots to all aerial parts, especially leaves and flowers (FIGURE 2-17). The air around a plant absorbs most of ground tissues, and vascular tissues (FIGURE 2-16). Similar that water but some of the water and all the minerals remain to our© own Jones epidermi & Bartletts, the epidermi Learning,s of a plant LLC protects the © Jones & Bartlett Learning, LLC inside the plant for its own use. Phloem (pronounced FLOW body from bacteria and fungi, and it inhibits water from NOT FOR SALE OR DISTRIBUTION em) carriesNOT sugars FORand vario SALEus orga ORnic comp DISTRIBUTIONounds as well as evaporating out of the body. “Ground tissue” is a somewhat vague term that refers to inner tissues in general. The ground

TABLE 2-2 The Tissues that Compose Most Plants1 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR1. SALEEpidermis OR DISTRIBUTION 2. Cortex2

3. Vascular tissues a. Xylem © Jones & Bartlett Learning, LLC b. Phloem © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION4. Pith (occurs only in stems)2NOT FOR SALE OR DISTRIBUTION

5. Mesophyll (occurs only in leaves and flowers)2

6. Secondary xylem (wood) © Jones & Bartlett Learning, LLC 7. Secondary© Jones phloem & (occurs Bartlett as part of bark) Learning, LLC NOT FOR SALE OR DISTRIBUTION 8. CorkNOT (occurs FOR as part ofSALE bark) OR DISTRIBUTION FIGURE 2-14 We often never notice the flowers of wind-pollinated trees because 1 Reproductive structures such as flowers and cones have additional tissues; these are they are very small, lack petals, and are located so high in trees. But after they release discussed in Chapters 9 and 22. their pollen, the flowers are abscised from the trees and fall. Shown here are long, 2 People often speak of cortex, pith, and mesophyll as tissues but technically each is a region stringlike clusters of the staminate flowers of pecan (Carya illinoensis); although of an organ, and each might be composed of various tissues. For example, leaf mesophyll © Jones &we oftenBartlett do not notice Learning, them while still in LLCthe trees, they are hard to miss when on © Jonesis the region& Bartlett between the upper Learning, epidermis and the lower LLC epidermis, and it consists of both NOT FORsidewalks, SALE cars, OR and roofs. DISTRIBUTION NOT FORphotosynthetic SALE tissue (the OR green cells)DISTRIBUTION and vascular tissue (the leaf veins). 26 Chapter 2: Overview of Plant Life

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. Vascular It can be confusing to compare the vascular systems of Pith Cortex bundles plants and animals without thinking about each carefully. © Jones & Bartlett Learning, LLC © JonesWe humans & Bartlett pump bloo Learning,d out of our LLC heart into a single wide NOT FOR SALE OR DISTRIBUTION NOT aorta,FOR which SALE then OR bran DISTRIBUTIONches into many large arteries, each of which in turn branches into narrower arteries that finally branch into arterioles and capillaries. No plant ever puts all its water, sugars, and minerals into just one large vascular bundle. Even the most slender stem will have 10 to 20 vascu- © Jones & Bartlett Learning, LLClar bundles; this provides pla©nts Joneswith safety & throBartlettugh red Learning,un- LLC NOT FOR SALE OR DISTRIBUTIONdancy. If an insect bites into NOTa stem FORand bre SALEaks one OR or two DISTRIBUTION vascular bundles, the stem will still have many others that are intact and functional (FIGURE 2-18). The description of plant structure to this point refers to young plants as well as to young growth at the ends of © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC FIGURE 2-16 This cross-section of a buttercup (Ranunculus) shows an arrangement branches and roots. This is called the primary plant body, and of tissuesNOT that occurs FOR in almost SALE all seed plant OR stems: DISTRIBUTION epidermis, cortex, a ring of all the tissuesNOT and orgaFORns areSALE produced OR byDISTRIBUTION cells located at the vascular bundles, and pith in the center. very tips of stems and roots. Herbs are plants that have only this primary body; examples include lilies, lettuce, lawn grass, and ferns. Herbs are usually small plants that live only a few months before they reproduce and die. Woody plants are © Jones &minerals Bartlett and water Learning, throughout LLC the plant. For example, leaves© Jonesdefined & asBartlett those tha tLearning, produce a seco LLCndary body inside their NOT FORproduce SALE sugar OR by DISTRIBUTION photosynthesis, and phloem carries most ofNOT primaryFOR SALE body. This OR is DISTRIBUTIONeasier to understand with less techni- that sugar out of the leaf into the stem; some is transported cal words: Woody plants are those that produce wood and downward where it nourishes roots while some is transported bark (FIGURE 2-19). In an herb, all cells mature into epidermis, upward to flowers and fruits. Xylem and phloem almost ground tissue, or vascular tissue; once these are formed, no always occur together in a small number of vascular bundles. immature cells are left. But in plants that will become woody, © Jones & Bartlett Learning, LLCthere is a sheet of cells that runs© throJonesugh all & the Bartlett vascular bun Learning,- LLC NOT FOR SALE OR DISTRIBUTIONdles; the cells within this sheNOTet do not FOR mat ure.SALE Instead OR the DISTRIBUTIONy divide and produce new cells; this region is the vascular cambium. Cells produced to the inner side of the vascular cambium become wood (technically called secondary xylem); those on the outer side become secondary phloem (which is © Jones & Bartlett Learning, LLC part of the ©bar Jonesk). All vasc & ularBartlett cambia Learning, share the sam LLCe basic NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

FIGURENOT 2-17 This FOR is a light SALE microscope OR view of DISTRIBUTION a vascular bundle in a stem of FIGURE 2-18 NOTThis is a cross-section FOR SALE of a small wisteria OR vine,DISTRIBUTION and the many dark holes sunflower (Helianthus annuus). The eight large round open cells at the bottom are are vessels in the xylem. Each is the open end of a long tube that runs deeply into the xylem vessels that carry water upward from the root to leaves and flowers. Just above stem, and the other part of each tube extended far into the part of the stem that was these are small, angular phloem cells that carry sugar. The upper mass of red cells are cut away. Even in this narrow young vine, water is carried by hundreds of vessels and if fiber cells that make a cap along the outer edge of the phloem, not only giving the one or two become damaged, the rest can still function. Each year, the vine would add © Jones &stem Bartlett strength to stand Learning, upright, but also to LLC protect the phloem from insects that might © Joneseven more & vessels Bartlett as it made Learning,more wood along the LLC edge of this wood, just interior to NOT FORtry SALE to eat into itOR or suck DISTRIBUTIONthe sap through a long proboscis, as aphids do. NOT theFOR bark. SALE OR DISTRIBUTION Overview of Plant Structure 27

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. carry out unusual functions and have shapes that fool even professional botanists. The spines of cacti are modified bud © Jones & Bartlett Learning, LLC © Jonesscales &of Bartlettaxillary buds Learning, even though LLC they have almost no fea- NOT FOR SALE OR DISTRIBUTION NOT turesFOR typical SALE of a ORbud scaDISTRIBUTIONle (FIGURE 2-20). The beautiful white or yellow flowers of daisies are actually entire groups of tiny flowers rather than being one single flower as it would appear (see Figure B2-1B). And palm trees, despite being big, hard, and long-lived, are herbs: They never make even a single cell © Jones & Bartlett Learning, LLCof wood nor do they have a vasc©ular Jones cambium. & Bartlett Plant structure Learning, LLC NOT FOR SALE OR DISTRIBUTIONis one of the easiest aspects of NOTbiolog yFOR to stud SALEy because OR pla ntsDISTRIBUTION do not run or fly away; we can walk up to them and look at them closely. Most structures are easy to see with the naked eye, even more are visible with an inexpensive hand lens.

FIGURE© 2- 19Jones It is easy to& distinguish Bartlett woody plantsLearning, from herbs here: LLC The trees are © Jones & Bartlett Learning, LLC woody plants,NOT the FORgrasses are SALE herbs. Even ORthough DISTRIBUTIONgrasses may live for many years, NOT FOR SALE OR DISTRIBUTION they never form secondary xylem or phloem (they never make wood or bark), whereas ❚❚ Overview of Plant almost all trees begin to add secondary xylem and phloem to their bodies even while they are only a few months old. Metabolism All organisms—plants, animals, fungi, and all the rest—must © Jones & Bartlett Learning, LLC © Jonestake in & energy Bartlett and raw Learning, materials fro LLCm their environment. This generalization has no exceptions whatsoever. We animals take NOT FORorganization, SALE OR but DISTRIBUTION can vary greatly in the speed with whichNOT FOR SALE OR DISTRIBUTION in both energy and raw materials as the organic materials we call they produce cells and in the amount of cells they produce. food. Plants do not eat, of course; instead they take in resources The vascular cambia of giant conifers and hardwood trees through several separate processes. Energy is provided by sun- produce massive amounts of wood and bark, whereas those light and is captured by the process of photosynthesis. The bulk of roses and other shrubs produce much less. Woody plants © Jones & Bartlett Learning, LLCof a plant’s body is composed© of Jones organic mole& Bartlettcules that Learning,can LLC also have cork cambia, sets of dividing cells that contribute all be traced back to the reaction of carbon dioxide and water waterproof, damage-resistantNOT cork FOR cells SALE to the bark. OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION during photosynthesis. Plants obtain the needed water through A word of caution before we leave this overview of their roots, and carbon dioxide is absorbed from air through plant structure. Although almost all plants are organized as the epidermis. Minerals are a fourth raw material plants need, described here, many plant parts have evolved such that they and these too are absorbed by roots. © Jones & Bartlett Learning, LLC Photosynthesis© Jones is & the Bartlett central metaLearning,bolism by LLC which NOT FOR SALE OR DISTRIBUTION plants acquireNOT energ FORy. For SALE the vast OR maj DISTRIBUTIONority of plants and algae, there is absolutely no alternative at all. The exceptions are parasitic plants that absorb organic material from a host plant. Plants are green because they contain the pigment chlorophyll, a molecule that both captures the energy of light © Jones & Bartlett Learning, LLC © Jonesand then & Bartlett passes tha tLearning, energy to oth LLCer chemicals, transform- NOT FOR SALE OR DISTRIBUTION NOT ingFOR them. SALE Throug ORh sevDISTRIBUTIONeral metabolic steps, the captured light energy forces carbon dioxide to react with water, which yields oxygen and carbohydrate. The oxygen diffuses out of leaves as a waste product; the carbohydrate is used as the starting point for all metabolic pathways (FIGURE 2-21). © Jones & Bartlett Learning, LLCPhotosynthesis only occur© sJones when light,& Bartlett chlorophyll, Learning, LLC NOT FOR SALE OR DISTRIBUTIONand carbon dioxide are present.NOT It does FOR not SALE occur at OR night, DISTRIBUTION in dark caves, deep in the oceans, nor does it occur after a plant has shed its leaves in autumn. Photosynthesis also does not occur in organs such as roots, bark, and flowers that do not have chlorophyll (FIGURE 2-22). Consequently the light © Jones & Bartlett Learning, LLC energy captured© Jones by pho &tosynthesis Bartlett musLearning,t be mov edLLC from NOT FOR SALE OR DISTRIBUTION leaves out toNOT other FOR organs SALE that do OR not phoDISTRIBUTIONtosynthesize, and this transport is carried out by phloem. Also energy must be FIGURE 2-20 This is Pereskia grandifolia, one of the few cacti that still produce stored from daytime to night and from summer to winter. large, easily recognizable foliage leaves. The spines that emerge from its leaf axils are Most plants store energy by polymerizing glucose molecules modified bud scales: There is an axillary bud there as we would expect, but the bud together into starch, which is more compact and stable than © Jones &scales Bartlett develop as spines, Learning, rather than as the LLC typical scales as in cottonwood (Figure 2-1).© Jonessugar. & A Bartlettfew plants, Learning, such as peanuts, LLC sunflower seeds, and NOT FORAll SALE plants produce OR at least DISTRIBUTION two types of leaves: foliage leaves and bud scales. NOT avocadoes,FOR SALE conv ORert glucos DISTRIBUTIONe to fats and store those as lipid 28 Chapter 2: Overview of Plant Life

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & BartlettAlternatives Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION BOX 2-2 Plants Without Photosynthesis

Are ordinary stems and© foli Jonesage leav es& rea Bartlettlly adaptations Learning, that LLCphotosynthesis, mutations tha© tJones curtail &leaf Bartlett development Learning, LLC improve photosynthesis?NOT Or do FOR plants SALE have pla ORnt-like DISTRIBUTION struc- became beneficial: Most holoNOTparasites FOR hav SALEe either OR smal DISTRIBUTIONl, ture just because that is the way things are? It is easy to take scale-like leaves or none at all. Dodder (Cuscuta) is one of the really common things for granted and not even ask ourselves few holoparasites that has any ordinary plant-like features if there are alternatives. We can create many models and con- left in its body (FIGURE B2-2A). It has long, slender stolon-like sider theoretical aspects, but we always want to verify our shoots with tiny leaves; it twines around host plants, insert- theories© Joneswith rea l& dat Bartletta, with empir Learning,ical eviden LLCce. That is a ing haustoria© (modifieJonesd & roo Bartlettts) into them Learning, and then groLLCwing principleNOT of theFOR scient SALEific meth ORod. DISTRIBUTION To see just how much of onward. Its NOTplant-like FOR features SALE of nodes OR andDISTRIBUTION internodes seem ordinary plant structure is the result of natural selection that to be necessary for it to spread from branch to branch of a improves photosynthesis, we need plants that do not photo- host or from one plant to another. synthesize, that are heterotrophic, and that have been het- Most holoparasites are subterranean. Their seedling erotrophic for so long that their bodies have had many mil- roots invade host roots, then the parasite’s embryo devel- © Jones &lions Bartlett of years toLearning, evolve without LLC being restricted by the need© Jonesops into & Bartletta rhizome-like Learning, shoot wit hLLC small, tough, protective, NOT FORto SALE photosynthesize. OR DISTRIBUTION The plants we need are parasitic plants. NOT scale-likeFOR SALE leaves. OR Being DISTRIBUTION underground, it is invisible to herbi- Approximately 4,000 species of parasitic plants occur in vores, and temperatures and humidity are more stable, less about 18 families (TABLE B2-1), and the ability for one plant variable than above ground. Many photosynthetic plants also to attack another has arisen evolutionarily about 12 times. have rhizomes, but many of their axillary buds grow upward Because there has been a dozen different starting points and as aerial, chlorophyllous branches; that never occurs in holo- because some groups had© morJonese time & tha Bartlettn others toLearning, become LLCparasites. A few of their axill©ary Jones buds gro &w Bartlett above the Learning,soil LLC adapted to their hosts,NOT parasitic FOR pla ntsSALE differ ORwidel DISTRIBUTIONy from surface as inflorescences, dispNOTlaying FOR flower SALEs to pol ORlinators DISTRIBUTION each other in structure, physiology, and so on. Two funda- (FIGURE B2-2B). mental types of parasitic plants occur. In other holoparasite species, development is even less Hemiparasites have chlorophyll and produce all, or at like that of ordinary plants: The subterranean “rhizome” has least part, of their own glucose; they merely obtain water, no leaves at all, no axillary buds, nodes, or internodes. The minerals,© Jones and perh &aps Bartlett some orga Learning,nic compounds LLC from their growing apex© consiJonessts of & a masBartletts of meri Learning,stematic cells LLC but has hosts.NOT Hemiparasites FOR SALE still hav ORe leav DISTRIBUTIONes with stomata and rather neither leafNOT prim ordiaFOR nor SALE a roo tOR cap. DISTRIBUTIONInternally, the “rhi- ordinary stems. Their roots, however, penetrate the epider- zome’s” tissues are not typical of either root or shoot, having mis or bark of host plants rather than soil. neither a single ring of bundles typical of a stem nor a central Holoparasitic plants have neither chlorophyll nor pho- mass of xylem as ordinary roots do. Even the surface is just tosynthesis: All of their ATP is produced by aerobic respira- a rough, irregular proliferation of cells rather than a smooth © Jones &tion Bartlett of glucose Learning, obtained from LLC the host plant, and they proba-© Jonessheet &of epidermis.Bartlett TheLearning, term “runn LLCer” is often used to indi- NOT FORbly SALE need little OR red DISTRIBUTIONucing power. In all cases, after the ancestralNOT cateFOR that SALE it is not OR an ordinary DISTRIBUTION plant organ. parasitic plants became holoparasitic and lost any need for Several holoparasitic plants live entirely within the body of their hosts. After their seedling root penetrates the host, the rest of the embryo dies. The “roots” grow deeper into the TABLE B2-1 Families that Contain Parasitic Plants host, penetrating its cortex, phloem, xylem, and pith, and they Parasitic plants occur in many families,© Jones but these listed& Bartletthere have some Learning,of the most LLCmake up 100% of the parasite’s© bod Jonesy. The para &site Bartlett has no sho Learning,ot LLC common or most familiar parasites.NOT For more FOR information SALE and excellent OR images, DISTRIBUTION go at all. The term “roots” is in quotNOTation FOR mar ksSALE because OR thes DISTRIBUTIONe to The Parasitic Plant Connection (www.parasiticplants.siu.edu/index.html). structures have no features typical of roots. Technically this Balanophoraceae is an endophyte, a plant that lives within another. The endophyte of the mistletoe Tristerix aphyllus, which grows inside Hydnoraceae the cactus Trichocereus chilensis, consists only of a branching web of uniseriate filaments of parenchyma cells; after some Loranthaceae© Jones (mistletoes & native Bartlett to North America) Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION months (?)NOT or yea FORrs (?), SALEthe filaments OR DISTRIBUTIONbecome multiseriate Orobanchaceae as their cells undergo longitudinal divisions (FIGURE B2-2C). At some point, a bit of phloem develops and an occasional, Rafflesiaceae isolated vessel element—the entire plant body has no roots, Santalaceae stems, leaves, epidermis, cortex, pith, and only a few cells of © Jones & Bartlett Learning, LLC © Jonesxylem & and Bartlett phloem. Deta Learning,iled studies LLC are needed, but it appears Viscaceae (mistletoes native to Europe) NOT FOR SALE OR DISTRIBUTION NOT thatFOR every SALE surface OR cell DISTRIBUTION of the endophyte body absorbs water, Overview of Plant Metabolism 29

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. minerals, and organic molecules from the host’s tissues. With merely obtain glucose from their hosts and then use various the entire body being absorptive, there is little need for con- types of respiration and anabolic pathways to synthesize all © Jones duction.& Bartlett When Learning, stimulated to LLC flower, parenchyma cells jus©t Jonesother &organic Bartlett mole cules.Learning, It would LLC not be surprising, how- NOT FORbelow SALE the host OR epidermi DISTRIBUTIONs proliferate into a nodule of callus, anNOT ever,FOR to SALEfind som eOR spe ciesDISTRIBUTION of parasitic plants that have become adventitious inflorescence apical meristem forms, and then it dependent on their hosts for at least some amino acids, lipids, breaks its way through the host epidermis. Because it has an or vitamins. Despite being so modified, the endophytic bodies ordinary apical meristem, the inflorescence has epidermis, of holoparasites are healthy, thriving, and well adapted to cortex, a ring of vascular bundles, and pith (but no chloro- respiration-based metabolism in a unique environment. phyll). Endophytes of Viscum© Jones minimum & Bartlett, Pilostyles Learning, thurberi, LLCHoloparasitic plants show© us Jones that man &y feaBartletttures of ordi Learning,- LLC and several Rafflesia speciesNOT are FOR similar SALE (FIGURE OR B2-2D DISTRIBUTION). nary plants must be very expensiNOTve and FOR risky: SALE After a pla ORnt has DISTRIBUTION After a green photosynthetic photoautotroph has pro- an alternative to photosynthesis, ordinary plant features are duced glucose, it then synthesizes all other organic compounds no longer adaptive, and mutations that prevent their devel- needed for its structure and metabolism (see Figure 2-21). It opment are advantageous. On the other hand, for plants that may be that some holoparasites do the same thing; they may do photosynthesize, plant-like bodies are worth the trouble. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

FIGURE B2-2A The slender orange stems are Cuscuta, a holoparasite that FIGURE B2-2B Prosopanche americana is holoparasitic, and most of its still© has Jones leaves and stems, & Bartlett but its internodes Learning, are extremely long LLC and slender highly modified© Jones body remains & underground;Bartlett it hasLearning, no need for photosynthesis, LLC and its leaves are tiny. It is producing adventitious roots that develop as NOT FOR SALE OR DISTRIBUTION obtainingNOT all its water FOR and nutrients SALE from the OR roots ofDISTRIBUTION its host. This flower is also haustoria, penetrating to the vascular tissues of the host, Justicia. highly modified: The black and white structure is a massive set of fused stamens.

Body of Tristerix aphyllus

Cactus phloem © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Cactus xylem

Cactus pith © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

FIGURE B2-2C The small cluster of cells with large red-stained nuclei are part of the body of FIGURE B2-2D The dark blobs do not belong to the visible shoot; instead, Tristerix aphyllus, a holoparasite whose vegetative body grows entirely within the body of its host, they are the flowers of a holoparasitic plant, Pilostyles thurberi, growing © Jones & inBartlett this case, the cactus Learning, Trichocereus chilensis LLC. The body of T. aphyllus consists of just parenchyma© Jones &completely Bartlett inside Learning,its host, the shrub Dalea LLC. Holoparasites typically must NOT FOR SALEand lacks leaves, OR stems, DISTRIBUTION epidermis, and virtually all other features of an angiosperm NOTbody. FOR SALEemerge from OR underground DISTRIBUTION or from inside their hosts when they flower. 30 Chapter 2: Overview of Plant Life

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. Sunlight CO2 + H2OC6H12O6 + O2 © Jones & Bartlett Learning, LLC Chlorophyll © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONCarbon dioxide + Water NOTSugar FOR + Oxygen SALE OR DISTRIBUTION Released to atmosphere

Some used by the leaf © Jones & Bartlett Learning, LLC for its own needs © Jones & Bartlett Learning, LLC

NOT FOR SALE OR DISTRIBUTIONMost transported to NOT FOR SALE OR DISTRIBUTION the rest of the plant

FIGURE 2-21 Simple diagram representing the raw materials and products of photosynthesis; carbohydrates produced by photosynthesis are subsequently converted to many other compounds. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION droplets within their cells, but plants never have adipose tis- of amino acids and nucleic acids; iron is attached to molecules sue like ours. that transfer electrons, and so on. Also like us, plants are not Respiration is another type of energy metabolism and especially effective at recycling minerals; we lose minerals as we it occurs in all organisms, with no exceptions whatsoever. As sweat, urinate, and defecate. Plants lose minerals has they shed © Jones &just Bartlett mentioned, Learning, glucose is use LLCd to store energy and to move© Jonestheir leaves,& Bartlett withered Learning, flowers, and frui LLCt. They pack their seeds NOT FORit SALEfrom organ OR to DISTRIBUTION organ. But a problem with glucose is that itNOT withFOR minerals SALE tha ORt the DISTRIBUTIONseedlings will need, and all those min- stores too much energy for certain needs. Cells force many erals are provided by the parent plant. The amount of minerals metabolic pathways to run by adding a small bit of energy a plant needs is surprisingly small; the ash that remains after a to two or three steps of the reaction. A molecule called ATP fire contains all the minerals that had been present in the wood. (adenosine triphosphate) provides just the right amount of Plants are master chemists. Starting with just glucose, energy for most of the steps© Jones (FIGURE &2-23 Bartlett). Glucose Learning,has about LLCminerals, and water, they synthesize© Jones every single & Bartlett molecule theLearning,y LLC 36 times as much energNOTy as is FOR carried SALE by ATP. OR Resp DISTRIBUTIONiration need for all aspects of their lifeNOT (TABLE FOR 2-3). They SALE synthesize OR DISTRIBUTIONall breaks down glucose and transfers its energy to ATP. During amino acids, nucleic acid, and fatty acids; they make all the photosynthesis, light energy is captured as carbon dioxide pigments of flowers and fruits; they make waxes, oils, resins, combines with water, producing oxygen and glucose. Respi- and fragrances. And poisons—many plants defend themselves ration is more or less the reverse: Oxygen and glucose react, from pests with an amazing array of poisons. Some are bitter producing© Jones carbon & dioxide Bartlett and waterLearning, with the LLCenergy being © Jones & Bartlett Learning, LLC transferredNOT toFOR ATP ratherSALE than OR being DISTRIBUTION given off as light. NOT FOR SALE OR DISTRIBUTION Plants also need minerals such as nitrogen, phosphorus,

potassium, iron, and others. Plants use these in much the same NH2 way we do; phosphate is needed for ATP; nitrogen becomes part C N N C CH © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning,HC LLCC Adenine N N NOT FOR SALE OR DISTRIBUTION NOT FOR OSALE– O OR– DISTRIBUTIONO–

–O ~~OP OP OP CH2 O

O O O HHH HH

Adenosine

Adenosine monophosphate

© Jones & Bartlett Learning, LLC © JonesAdenosine & Bartlett diphosphate Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Adenosine triphosphate FIGURE 2-22 Only the leaves of these palms (Washingtonia filifera) are green and photosynthetic, they are the only parts of the trees that produce sugar. All other parts, such as the long stems and the underground root systems, have no chlorophyll and FIGURE 2-23 Adenosine triphosphate. Breaking off the last phosphate to produce adenosine © Jones must& Bartlett obtain all their energyLearning, in the form of LLC sugars transported downward from the © Jonesdiphosphate &(ADP) Bartlett results in a more Learning, stable set of electron LLC orbitals, and energy is given off. The NOT FORleaves SALE by phloem. OR DISTRIBUTION NOTsame FOR is true of removingSALE the OR second DISTRIBUTIONphosphate, but not the third. Overview of Plant Metabolism 31

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & BartlettPlants Learning, and LLC People © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION BOX 2-3 Toxic Plants

Consider two facts: (1)© Pla Jonesnts live &amo Bartlettng herbi vores,Learning, and LLCsubstance P, which specifically ©stim Jonesulates oth &er Bartlett nerve cells Learning,that LLC (2) the world is full of uneaten plants. What is the cause? Many normally respond when we are being burned. Artificial selection plants produce toxic compNOTounds: FOR Poi SALEson ivy, ORdeat hDISTRIBUTION camas, by humans has resulted in chiliNOT peppers FOR that rang SALEe from OR hav ingDISTRIBUTION poison hemlock, and deadly nightshade are familiar examples, almost no capsaicin (bell peppers) to some that are dangerous but the full list of toxic plants is very long. Many plants we (cayenne, chiltepin, and Thai). Capsaicin is hydrophobic, and think of as being nonpoisonous are only harmless because we thus, drinking water will not cool your mouth; however, the fat stop eating© Jones things tha& tBartlett are bitter or Learning, that burn our LLC mouths: Few in cheese, butter,© Jones and milk & will Bartlett absorb it andLearning, give some relief.LLC people would eat enough chili peppers to get a lethal dose. The Cardioactive compounds. Digitoxin and digoxin in Digitalis followingNOT are FOR some toxinSALEs in ORplants DISTRIBUTION we live with. Fascinating (foxglove) inhibitNOT a FORset of pro SALEteins tha ORt use DISTRIBUTION the power of ATP to and well-illustrated accounts of many are given in Handbook pump sodium and potassium across a membrane. When this of Poisonous and Injurious Plants by Lewis S. Nelson, Richard pump is blocked in heart cells, it leads to an increase in the D. Shih, and Michael J. Balick (2007, Springer). concentration of calcium within the cells. Although foxglove © Jones & Bartlett Learning, LLC © Jonesleaves &are Bartlett injurious Learning,if eaten improperly, LLC these chemicals are used medicinally to slow and strengthen heartbeat. NOT FOR SALE OR DISTRIBUTION NOT FORCyanogenic SALE ORglycosides. DISTRIBUTION These are nontoxic in the plant, but enzymes in our digestive system cleave them into two parts: a sugar and cyanide. Cyanide inhibits the final step in aerobic respiration, preventing generation of ATP. These © Jones & Bartlett Learning, LLCtoxins are found in some of our© mosJonest comm &on Bartlett fruits—Malus Learning, LLC (apples) and Prunus (“stone fruits” such as cherries, peaches, NOT FOR SALE OR DISTRIBUTIONapricots)—but in parts that weNOT do not FOR eat such SALE as app ORle see DISTRIBUTIONds or peach pits. Poisoning most often occurs when apricot seeds are used as components of herbal medicines. Mitotic inhibitors. Microtubules create the spindle that © Jones & Bartlett Learning, LLC pulls chromosomes© Jones to &opp Bartlettosite ends Learning, of the cell LLCduring nuclear division. The alkaloid colchicine in autumn crocus, NOT FOR SALE OR DISTRIBUTION Colchicum NOTautumnale, FOR prevents SALE theOR ass DISTRIBUTIONembly of microtu- FIGURE B2-3 Each leaf of poison ivy has three leaflets and the defensive compound bules. Cells exposed to this poison cannot form a spindle, urushiol. and division fails. We humans have many tissues with rapidly dividing cells, such as the lining of our digestive tract, bone Anticholinergic (antimuscarinic) poisons. Many nerve cells marrow cells that produce red blood cells, and seminiferous © Jones &have Bartlett receptors thaLearning,t detect the pres LLCence of a small molecule called© Jonestubules & in Bartlett men. Catharanthus Learning, roseus LLC (also called Vinca rosea, NOT FORacetylcholine, SALE OR which DISTRIBUTION causes a reaction in the nerve cells when itNOT periwinkle)FOR SALE pro ducesOR DISTRIBUTIONthe alkaloids vinblastine and vincris- binds to the receptors. Plants such as Atropa (deadly nightshade) tine that also block cell division; these are used in chemo- and Datura (jimsonweed) produce chemicals that bind to one therapy to stop cancer cells from dividing. of these receptors (called the muscarinic receptor), preventing Toxalbumins. These proteins bind to ribosomes and pre- acetylcholine from stimulating proper nerve transmission. vent them from translating messenger RNA into protein. Nicotine-like alkaloids.© JonesAlkaloids &are Bartlett small mole Learning,cules that LLCRicinus (castor bean) produces© Jonesthe toxa lbumin& Bartlett ricin, Learning,one LLC contain nitrogen and somNOTewhat FOR resem bleSALE amino OR acids. DISTRIBUTION Alka- of the most toxic substances knoNOTwn. FOR Jatropha SALE species OR (coral DISTRIBUTION loids of Conium (poison hemlock), Nicotiana (tobacco), and bean) has a higher concentration of a related toxalbumin, and Sophora (mescal bean) block another acetylcholine receptor a single seed can cause severe poisoning. (this one called the nicotinic subtype). Symptoms occur in the Urushiol. About half of all people are allergic to urush- parasympathetic and sympathetic parts of the nervous system, iol, an oily substance in species of Toxicodendron (poison ivy, the brain,© Jones and the junctions& Bartlett where Learning, nerves attach LLCto muscles. poison oak,© and Jones poison &sumac). Bartlett All par Learning,ts of these pla LLCnts can ConvulsantNOT FOR poisons. SALE The OR small DISTRIBUTION tree Strychnos produces trigger an allergicNOT FORreaction. SALE OR DISTRIBUTION strychnine, which causes motor nerve cells to be hyperexcit- Remember that these plants do not have toxic com- able and results in convulsions. Several other plants produce pounds in order to protect themselves, or with the purpose convulsants. of keeping herbivores away. It is just that toxic or injurious Capsaicin. Chili peppers such as habaneros, jalapeños, and plants are more likely to be left uneaten compared with non- © Jones &tabascos Bartlett in the genuLearning,s Capsicum LLC contain capsaicin, which induces© Jonestoxic plants& Bartlett and ther Learning,efore are mor LLCe likely to produce more NOT FORsome SALE of our OR sens DISTRIBUTIONory nerve cells to release a chemical calledNOT seedsFOR and SALE more progeny.OR DISTRIBUTION 32 Chapter 2: Overview of Plant Life

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. TABLE 2-3 Chemicals that Plants Produce Starting with Glucose proteins. Smaller pieces of RNA, often called microRNA, act by binding to various components of the cell, activating some, © Jones &All Bartlett chemicals in a plantLearning, are produced with LLC glucose as a starting point. Even © Jonesinhibiting & Bartlett others, and Learning, in general fine-tunin LLC g the activities of NOT FOR fragrancesSALE and OR nectars DISTRIBUTION that are released from the plant are synthesized from NOT manyFOR genes. SALE The ORDNA DISTRIBUTION of each species is unique; for example, glucose. Only the most familiar chemicals are listed here. cherries (Prunus avium) and peaches (Prunus persica) have Chemicals that All sugars almost identical DNA, but the information in several genes in contain no minerals one differs just enough from that of the other so that cherries Carbohydrates are small, red, and shiny whereas peaches are large, yellow, Lipids © Jones & Bartlett Learning, LLCand fuzzy, and each has distinct© flavorsJones and & aromas. Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONA plant, just like any othNOTer orga FORnism, SALEalso uses OR infor DISTRIBUTION- Waxes mation from the environment. Environmental information Pigments must be perceived then transferred to where it is needed, and finally the plant must respond appropriately. While the Many vitamins plant is still nothing more than a dormant seed, the envi- Chemicals© Jonesthat &Amino Bartlett acids Learning, LLC ronmental infor© Jonesmation it& resp Bartlettonds to isLearning, often very simple: LLC It containNOT nitrogen FOR SALE OR DISTRIBUTION is warm enoughNOT to FOR germin SALEate. As ORtemp DISTRIBUTIONeratures climb from Nucleic acids winter to springtime, at some point they are warm enough and many seeds then respond by becoming active, respiring Some hormones more rapidly, and germinating. Seeds of other species remain Some pigments dormant because they are dry, not cold; they need to detect © Jones & Bartlett Learning, LLC © Joneswhen &their Bartlett surroundings Learning, have beco LLCme wet enough to sup- Chemicals that Some amino acids contain sulfur. NOT FOR containSALE various OR DISTRIBUTION NOT portFOR a growing SALE seedling. OR DISTRIBUTION minerals Chlorophyll contains magnesium. The environment also supplies a large amount of more complex information, in many forms (FIGURE 2-24). Sunlight Cytochromes that carry electrons contain iron. provides the energy for photosynthesis, of course, and it also ATP contains phosphorus. indicates the direction up (the direction of brighter light) © Jones & Bartlett Learning, LLCfrom down (the direction of ©less Jones light and & mor Bartlette shade). Learning, In LLC Calcium pectate is the glue that binds each cell to its all parts of the world except near the equator, sunlight pro- neighboringNOT cells. FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION vides information about seasons: Days are shorter in winter, longer in summer. By detecting this, a plant measures the season and responds by flowering and fruiting at the correct time and by becoming dormant in autumn. Roots are not or irritating, others kill animals quickly; some of the most toxic © Jones & Bartlett Learning, LLC exposed to ©sunlig Jonesht, but & the Bartletty detect gravLearning,ity and thu LLCs know chemicals interfere with cells in the brain and nervous system. AlthoughNOT we FOR humans SALE need a compOR lexDISTRIBUTION diet that includes several NOT FOR SALE OR DISTRIBUTION amino acids, fatty acids, and vitamins that we cannot make for ourselves, that is never true of plants. Their balanced diet is sunlight, carbon dioxide, water, and minerals. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR❚ SALE❚ Overview OR DISTRIBUTION of Information NOT FOR SALE OR DISTRIBUTION in Plants A universal feature of all known life on Earth is that DNA (deoxyribonucleic acid)© is Jonesused to sto &re Bartlett information. Learning, Just as LLC © Jones & Bartlett Learning, LLC with energy and matter, NOTorganisms FOR tak SALEe in infor ORmation, DISTRIBUTION store NOT FOR SALE OR DISTRIBUTION it, move it from place to place, transform it, use it, and then pass it onto their offspring when they reproduce. The great- est source of information for any individual is its parents: the DNA contained in the sperm cell and egg cell that initiated the life of© the Jones individual. & Bartlett In plants, DNALearning, is stored inLLC the nucleus © Jones & Bartlett Learning, LLC of each cell, as well as in plastids and mitochondria, which FIGURE 2-24 All plants here obtain energy from their environment, but think of the NOT FOR SALE OR DISTRIBUTION two trees. They bothNOT obtain FOR information SALE about which OR way DISTRIBUTION is up (the opposite direction are also present in all living plant cells. When a cell needs to of the force of gravity pulling on all parts). For the grasses in the pasture, up is in the use some of the information, it transforms the needed infor- direction of the brightest light, but for the tree on the right (closer to the shed), the mation by making messenger RNA (ribonucleic acid), and brightest light is away from the larger tree that is shading it, so “bright” and “up” are then it transfers that information to the area of the cell where not the same thing for it. These trees also need to detect the approach of winter and © Jones &it isBartlett needed. Most Learning, of the infor LLCmation is further transformed© Jonesabscise their& Bartlettleaves while they Learning, can, and they probably LLC detect the presence of many NOT FORas SALE the messenger OR DISTRIBUTION RNA guides the production of specificNOT insectsFOR and SALE fungi as well. OR DISTRIBUTION Overview of Information in Plants 33

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. example, mosses never have xylem or phloem and they never have seeds either. As a second example, ferns always have © Jones & Bartlett Learning, LLC © Jonesvascular & Bartletttissue but the Learning,y never repr LLCoduce with seeds. Several NOT FOR SALE OR DISTRIBUTION NOT aspectsFOR SALEof the gro ORups inDISTRIBUTION TABLE 2-4 are not quite accurate, but the groups and terms presented there have been used for more than 100 years, and you will still encounter them often in books about gardening and roadside flowers. An overview of them will be given here. Definitions of important terms © Jones & Bartlett Learning, LLCare grouped together in TABLE© 2-5 Jones. & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONMosses, liverworts, and NOThornworts FOR are SALE often groORuped DISTRIBUTION together and called bryophytes (pronounced BRY oh fights) (FIGURES 2-26 to 2-29). They are similar to each other because they not only lack vascular tissues and seeds, but also because plants in all three groups are haploid. Mosses, liverworts, and © Jones & Bartlett Learning, LLC hornworts are© Jonesunique amo & Bartlettng plants bec Learning,ause they live LLC their NOT FOR SALE OR DISTRIBUTION lives with onlyNOT one FOR set of chroSALEmosomes, OR DISTRIBUTION not two. Their bod- FIGURE 2-25 When these bulbs became active and started growing, all parts were ies are very simple, not much more complex than the algae so deeply buried in soil that they could not detect any sunlight. But both new roots and that were the ancestors of plants. new leaves detect gravity, with roots growing downward, leaves growing upward.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORwhich SALE direction OR DISTRIBUTION is down. Deeply buried bulbs also detecNOTt FOR SALE OR DISTRIBUTION gravity and respond in two opposite ways: Roots follow grav- TABLE 2-4 Overview of the Main Clades of Organisms ity downward, whereas shoots grow upward (FIGURE 2-25). We are now learning that some plants are much more per- Archaea ceptive than we ever sus©pected. Jones Tendr & Bartlettils bend towa Learning,rd any- LLC © Jones & Bartlett Learning, LLC thing that gives them even the slightest touch, leaves detect Bacteria NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION the growth of a single fungus spore on their surface, and Eukarya some orchids detect whether a pollinator has merely landed on one of their flowers or if it has actually taken the pollen. Animals Various parts of a plant itself create information that Fungi informs© Jonesthe rest &of Bartlettthe plant Learning,of their activities. LLC Healthy © Jones & Bartlett Learning, LLC leaves produce hormones that are carried to the roots: A Photosynthetic eukaryotes NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION large amount of hormone indicates the leaves are active Algae [red algae, brown algae, green algae, and others] and need water. The roots respond by growing and absorb- ing water and nutrients. In autumn, as leaves prepare to Plants [also called true plants, land plants, or embryophytes] be shed, they stop producing the hormone, so the amount Plants without vascular tissue [mosses, liverworts, hornworts only] of the hormone decreases, indicating the leaves no lon- © Jones &ger Bartlett need water Learning,. Roots resp LLCond by slowing their growth© Jones & PlantsBartlett with vascular Learning, tissues [vascular plants]LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION and conserving their energy. After a flower is pollinated, Plants without seeds [vascular cryptogams] the developing fruit sends signals indicating that it needs nutrients for itself and the embryonic seeds inside. This Lycophytes [often called “fern allies”] communication among the parts of a plant is necessary to Ferns keep the plant integrated© andJones all par &ts Bartlett developing Learning, in coor- LLC © Jones & Bartlett Learning, LLC dination. It is especially remarkable considering the long Plants with seeds [spermatophytes] NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION distances involved between the thousands of leaves, flow- Cycads ers, branches, and roots of a large tree. Gingko

Gnetophytes ❚❚ Overview© Jones & Bartlett of Plant Learning, LLC © Jones & Bartlett Learning, LLC Conifers DiversityNOT FOR SALE and OR Evolution DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Angiosperms All the thousands of species of plants of the world are not Basal angiosperms [several groups] just a hodgepodge of randomly associated features. Instead there are several large, recognizable groups such as mosses, Monocots © Jones &ferns, Bartlett conifers, Learning, and angiosperms. LLC Within each group, we are© Jones & Bartlett Learning, LLC Eudicots NOT FORlikely SALE to find OR certa DISTRIBUTIONin features and unlikely to find others. ForNOT FOR SALE OR DISTRIBUTION 34 Chapter 2: Overview of Plant Life

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. TABLE 2-5 Terms Used for Plant Groups © Jones &Several Bartlett informal terms Learning, are used for various LLC plant groups. You will encounter many of© these Jones in books and & articles Bartlett about plants. Learning, LLC NOT FOR ThallophytesSALE OR and DISTRIBUTIONA thallus (plural, thalli, pronounced THAL eye) is a bodyNOT that is FORnot composed SALE of roots, ORstems, andDISTRIBUTION leaves, and which does not have typical plant cormophytes tissues. The only plants that are thallophytes are hornworts and the “thalloid” liverworts (liverworts without stems and leaves). Many algae are unicellular, but in those that have a multicellular body, the body is called a thallus. For example, the body of a kelp is a thallus. The bodies of fungi (mushrooms, puffballs, brackets) and lichens are also called thalli. The term is never used for animals. All plants that are not thallophytes are cormophytes, plants whose body consists of at least stems (the earliest plants lacked leaves and roots). The© termJones “cormophyte” & Bartlettis rarely used because Learning, virtually all plants LLC are cormophytes, and we simply say “plant.”© The Jones body of a cormophyte & Bartlett is just a Learning, LLC “body,”NOT it is FOR not “corm” SALE (“corm” refers OR to modified DISTRIBUTION subterranean, vertical stems with papery leaves, as inGladiolus NOT). FOR SALE OR DISTRIBUTION Many algae are unicellular; that means their body consists of just one cell. This never occurs in plants: all plants have multicellular bodies, there are no exceptions.

Nonvascular and Plants that lack vascular tissues are nonvascular plants. The only ones are mosses, liverworts, and hornworts. All other plants have vascular vascular plants tissues and so are vascular plants, also known as tracheophytes. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Spore-bearingNOT FOR and SALEWe need OR to be careful DISTRIBUTION here because popular books and many biology texts are misleadingNOT FORabout spore-bearing SALE plants. OR All DISTRIBUTION plants produce spores, seed plants there are no exceptions. The term “spore-bearing plant” usually refers to those plants that never make seeds, which are mosses, liverworts, hornworts, lycophytes, and ferns. All other plants make seeds as well as spores. A common term for “spore-bearing plant” is cryptogam: Before the invention of lenses, spores could not be seen, so botanists thought that ferns and the others had “hidden seeds” (crypto = hidden; gam = seed). Ferns and lycophytes have vascular tissue but no seeds, so they are vascular cryptogams whereas mosses, liverworts, and hornworts are nonvascular cryptogams. © Jones & Bartlett Learning,Whereas LLC all plants produce spores, only seed plants© produce Jones seeds, and& aBartlett technical term forLearning, them is spermatophytes LLC. All seed plants are NOT FOR SALE OR DISTRIBUTIONvascular plants, with no exceptions, so it is not necessaryNOT to say “vascularFOR seedSALE plants” orOR “vascular DISTRIBUTION spermatophytes.” Gymnosperms (cone- Until just a few years ago, all seed plants that did not produce flowers were grouped together as “gymnosperms,” which included cycads, Gnetales bearing seed plants) (sometimes called gnetophytes)*, ginkgos, and conifers. But new evidence is interpreted as showing that angiosperms have the same ancestor as and angiosperms these groups (they all share a common ancestor), so all seed plants should either be grouped together, or each group should be kept separate: It is (flower-bearing plants) incorrect to include some groups (“gymnosperms”) and leave out others (angiosperms). At present, we use the general term “seed plant” to refer to all© of Jonesthem, or we refer& Bartlettto each small group Learning, individually. The termLLC “gymnosperm” should not be used but you© will Jones still see it even& Bartlettin modern books Learning, LLC andNOT papers. FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION The term “angiosperm” is derived from the formal name for flowering plants, Angiospermae in older classifications, Magnoliophyta or Angiosper- mophyta in most modern treatments. Many authors, even in technical journals, use the term “flowering plants” rather than “angiosperms.”

Basal angiosperms, As explained in the text, until recently all angiosperms were classified as either monocots (“monocotyledons” is a longer, older name) or dicots (di- monocots,© Jones and & Bartlettcotyledons), butLearning, now we realize some LLC of the species we had classified as dicots© had Jones become evolutionarily & Bartlett distinct very Learning, early in angiosperm LLC history, eudicots so now we refer to those as basal angiosperms; examples are Amborella trichopoda (the most basal of all known living flowering plants), water lilies, NOT FOR SALEMagnolia OR and its DISTRIBUTION relatives, and a few others; see Figure 23-9). The old term “dicot”NOT had to beFOR abandoned, SALE and a new OR term, DISTRIBUTION eudicot, refers to “all the dicots minus the basal angiosperms.” Most basal angiosperms resemble eudicots very strongly; their leaves are similar (broad and with a petiole, not long and strap-shaped like leaves of monocots) as is the arrangement of vascular bundles in their stems and many other features. Therefore it is still common to see people refer to “dicot leaves” rather than “basal angiosperm and eudicot leaves.”

© Jones &Lower Bartlett plants and Learning, These are LLC completely nontechnical terms and have no© set Jonesdefinition. All & people Bartlett would consider Learning, seed plants to be LLCamong the “higher plants” and higher plants cryptogams to be “lower plants,” but it is often difficult to be certain exactly what an author means when these terms are used. These terms desig- NOT FOR SALE OR DISTRIBUTIONnate grades, a system no longer used, and these two NOTterms should FOR not be usedSALE any longer. OR DISTRIBUTION

* Names in formal classifications are capitalized but informal names are not. The informal names of some of the groups here are: angiosperms, conifers, gnetophytes, and mosses. Their formal names are: Angiospermophyta, Coniferophyta, Gnetales (some people use Gnetophyta), and Musci (an old name for mosses) or Bryophyta (a newer name for mosses).

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION All other groups of plants have vascular tissue and are gymnosperms) and those with “clothed seeds” (the angio- diploid. Many vascular plants resemble bryophytes in being sperms, often called the flowering plants). Here, “clothed unable to form seeds; they reproduce using spores and are seeds” refers to seeds formed inside a fruit in contrast to typically called the spore-bearing plants. These are often naked seeds that are produced in a cone. The term “naked” referred© Jonesto as fern s& and Bartlett “the fern Learning,allies” (FIGURES LLC 2-30 to 2-32). refers to the© timeJones when & a Bartlettpine cone isLearning, extremely youn LLCg; at AnNOT old FORway of SALEthinking OR abo utDISTRIBUTION plants is that ferns and that point, NOTits sca lesFOR are farSALE enoug ORh apa DISTRIBUTIONrt that you can look “fern allies” had advanced above the bryophytes as they in and see the individual naked ovules. The carpels of angio- evolved to have vascular tissue, but then their evolution sperms are always sealed, and the ovules are never visible “stagnated” while other vascular plants continued to advance without cutting the young fruit open. There are other differ- evolutionarily to the point where they could make seeds ences between gymnosperms and angiosperms that make us © Jones &as wellBartlett as vasc Learning,ular tissues. The LLC more advanced seed plants© Jonesthink &of angiospermsBartlett Learning, as being mor LLCe advanced: Angiosperms NOT FORthen SALE divided OR into DISTRIBUTION two groups, those with naked seeds (theNOT haveFOR more SALE comp ORlex DISTRIBUTIONwood and leaves, as well as several Overview of Plant Diversity and Evolution 35

FIGURE 2-26 Mosses cover the rocks in this stream in the Olympic National Park. Mosses have© Jones no xylem or phloem& Bartlett and cannot conduct Learning, water very well, LLC so they are FIGURE 2-29 Hornworts© Jones such as &this BartlettPhaeoceros laevis Learning, are widespread, but LLC they typicallyNOT very small FOR plants. Although SALE we associateOR DISTRIBUTION mosses with damp places, many are only thrive whenNOT it has been FOR rainy for SALEawhile; they OR grow in DISTRIBUTION shady places, sometimes adapted to deserts, being inactive except on rare days when it there is rain, fog, or dew. on bare soil, sometimes mixed among grasses. Each long projecting cylinder (about 1 cm long) is the “horn” and is actually the diploid portion of the plant (technically, a sporophyte): Each horn is the same phase of the life cycle as is a tree, bush, shrub, or any other familiar plant. The small flat patches of tissue in contact with the soil are the gametophytes, the haploid part of each plant: It is the part that is similar to mosses, © Jones & Bartlett Learning, LLC © Jonesleafy liverworts, & Bartlett and thalloid Learning,liverworts. The life cycle LLC of plants is much more complex NOT FOR SALE OR DISTRIBUTION NOT thanFOR that ofSALE animals, but OR is fascinating. DISTRIBUTION

© Jones & Bartlett Learning, LLCmodifications that improve ©pho Jonestosynthesis. & Bartlett Angiosperms Learning, LLC NOT FOR SALE OR DISTRIBUTIONalso cooperate with animals thaNOTt pol FORlinate theirSALE flower ORs and DISTRIBUTION distribute their seeds whereas conifers never rely on animals for pollination, and only a few cooperate with animals for seed dispersal. We can arrange the different groups in a linear © Jones & Bartlett Learning, LLC sequence that© Jonesseems to & reflec Bartlettt plant evoLearning,lution. The LLCearliest NOT FOR SALE OR DISTRIBUTION true plantsNOT were morFORe advan SALEced ORthan DISTRIBUTION algae because they had simple tissues and organs but little else. This would be FIGURE 2-27 These are plants of the leafy liverwort Bazzania trilobata. As with mosses, the bodies of leafy liverworts consist of a stem and leaves, but never any roots, the moss level of evolution. Other plants advanced to the xylem, or phloem. It is usually necessary to have a hand lens or magnifying glass to level of having vascular tissues, others continued evolving distinguish between a leafy liverwort and a moss. to the point of having seeds. Then one group evolved more © Jones & Bartlett Learning, LLC © Jonesthan all& theBartlett rest, to Learning,the point of havLLCing flowers and fruits. NOT FOR SALE OR DISTRIBUTION NOT SomeFOR would SALE even OR refer DISTRIBUTION to angiosperms as the “pinnacle” of plant evolution. In this method, emphasis is placed on the level to which a group has evolved. The technical word for level is grade; we are grouping plants into grades, with the lowest grade being nonvascular plants, the highest grade © Jones & Bartlett Learning, LLCbeing angiosperms. We still encoun© Jonester this & concep Bartlettt of grade Learning, LLC NOT FOR SALE OR DISTRIBUTIONwhen people refer to the “lowerNOT plants” FOR and SALE “higher ORplants.” DISTRIBUTION This grouping by grade is very handy if you are not too wor- ried about accuracy, but we now have a newer method of grouping plants, one based on groups that consist of all the species that evolved from a common ancestor. Such a group © Jones & Bartlett Learning, LLC is a clade.© Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION Fortunately,NOT gro FORuping SALE plants intoOR clades DISTRIBUTION gives us almost the same result as grouping them into grades (FIGURE 2-33). We need to abandon only a few of the old terms. For exam- FIGURE 2-28 This is a rather common thalloid liverwort (Conocephalum conicum) ple, we no longer use the term “gymnosperm.” We suspect— that is easy to recognize: Its bodies never have any hint of leaves or stems, they are flat but are not at all certain—that seeds evolved only once. If © Jones &and Bartlettabout 1 cm wide, Learning, and they occasionally LLC fork into two growing points. Their upper © Jonesso, then & allBartlett seed plants Learning, alive today descendeLLC d from that orig- NOT FORsurface SALE has a distinctive OR DISTRIBUTION diamond-like pattern that resembles reptile skin. NOT inalFOR species SALE of see ORd pla DISTRIBUTIONnt, and we say it was the common 36 Chapter 2: Overview of Plant Life

(A) (B) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC FIGURE 2-30 (A) This Selaginella lepidophylla is used as an example of a “fern ally” because of its interesting biology: It is a resurrection plant. It is a diploid vascular plant with xylem and phloem,NOT and itFOR grows in harshSALE deserts OR with long DISTRIBUTION dry periods. This photograph shows the plant after autumn rains,NOT when FOR the plant SALE is hydrated, healthy,OR DISTRIBUTION and active. Compare with Figure 2-30B. (B) This is also Selaginella lepidophylla but after a long dry period; the plant has curled up, minimizing the amount of surface exposed to dry air and UV light. Although it looks dead, it is not only alive but very healthy, merely dormant, somewhat like a dry seed that is alive. After a rain, these plants would uncurl and look like those in Figure 2-30A. If forcibly uncurled now, the inner parts would be bright green. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ancestor to all seed plants. Some of its descendants evolved such as angiosperms or conifers or seed plants, the ances- into cycads, others became ginkgos, another group evolved tors lived in the very distant past. Consequently, we can into conifers, and still another group became angiosperms. never be completely certain which ancient, extinct group There are two important points here. The first is that a clade was the common ancestor of any modern clade; instead consists of an ancestor and© Jones all its descendants & Bartlett, so theLearning, group LLCwe have to study the living orga© Jonesnisms and & tryBartlett to infer Learning,the LLC “seed plants” is acceptable—itNOT isFOR a clade SALE. But the OR wor DISTRIBUTIONd “gym- features the common ancestorNOT had. FOR Using SALEangiosperms OR DISTRIBUTIONas nosperms” refers to all seed plants except angiosperms; an example, all modern as well as fossil angiosperms have it includes the common ancestor of seed plants but only vascular tissues; they produce flowers and they make seeds, some, not all descendants, so “gymnosperms” is not a clade. they never make anything similar to a pine cone, and they We prefer to not to use the term “gymnosperm” if we care are never haploid like bryophytes. From this we assume that about© being Jones accurate. & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC TheNOT second FOR impo SALErtant poinORt isDISTRIBUTION that the ancestors of any NOT FOR SALE OR DISTRIBUTION clade of living organism all lived in the past, and for clades

FIGURE 2-32 This is a single plant of sword fern (Polystichum munitum); it has a © Jones & Bartlett Learning, LLC short vertical stem© thatJones supports the& many Bartlett leaves, and belowLearning, ground are many LLC fibrous roots. Ferns are diploid and have xylem and phloem, but their spores grow into tiny NOT FOR SALE OR DISTRIBUTION haploid plants thatNOT resemble FOR the bases SALE of hornworts OR (Figure DISTRIBUTION 2-29). This large sword FIGURE 2-31 These plants of Equisetum telmateia are diploid vascular plants that fern pictured here is the equivalent of a hornwort horn (both are sporophytes). In are now considered to be part of the ferns. These are descendants of an ancient group: rainy areas of the Pacific Coast of the United States, sword ferns are so abundant they Fossils of plants that have similar features can be found in rocks as much as 150 million resemble meadows of grass; indeed, millions of years ago before grasses evolved, most years old. Equisetums are called horsetails or scouring rushes, and are distinctive in “grasslands” were actually huge patches of ferns. Ferns and dinosaurs were abundant © Jones &having Bartlett a very coarse Learning,surface (due to having LLC silica in their cell walls); they can be found © Jonesat the same & time,Bartlett long before Learning, grasslands existed—the LLC herbivorous dinosaurs ate ferns NOT FORalmost SALE everywhere, OR along DISTRIBUTION streams and along railroad tracks in moist areas. NOT andFOR fern allies. SALE OR DISTRIBUTION Overview of Plant Diversity and Evolution 37

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. Vascular plants stopping completely. This is the second problem with grouping plants into grades: It assumes that all plants have the same Seed plants © Jones & Bartlett Learning, LLC © Jonesgoal, that& Bartlett having vasc Learning,ular tissue and LLC seeds and flowers is the NOT FOR SALE OR DISTRIBUTION NOT optimumFOR SALE way a plaORnt DISTRIBUTIONcan be adapted to its environment. We Cryptogams “Gymnosperms” Angiosperms no longer believe this. We now realize that there are multiple ways for an organism to be adapted to its environment. This is reflected orts rs phytes in the questions “What are the alternatives?” and “What are s nw cads rn © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC cophytes the consequences?” Consider mosses and angiosperms, two

Liverworts Mosses Hor Ly Fe NOTCy FORGne to Ginkgo SALEfe Coni Basal ORangiosperms Monocots DISTRIBUTIONEudicots groups at the opposite end ofNOT the old FOR grade SALE system. ORMoss DISTRIBUTIONes are tiny and simple whereas most angiosperms are large and complex. But mosses are very well-adapted to their environ- H ment: They thrive in low light, on brick walls or bare stone; Origin of they need only enough sunlight, water, and mineral nutri- G flowers © Jones & Bartlett Learning, LLC ents to make© aJones few spo res& Bartlettand then the Learning,y can reproduce. LLC In Origin of seeds the moss clade, evolution by natural selection has found NOT FOR SALE OR DISTRIBUTION(once? twice?) NOT FOR SALE OR DISTRIBUTION F solutions to survival that work well for small, simple plants. E Having vascular tissue and seeds and so on would not make D a moss any more adapted than it is without them. This is a C crucial point I will emphasize many times: There are many, © Jones & Bartlett Learning, BLLC © Jonesdiverse & waysBartlett to be Learning,adapted, numer LLCous ways of thriving. A NOT FOR SALE OR DISTRIBUTION NOT ThereFOR is SALE not one OR single DISTRIBUTION structure or physiology that will be optimum for every organism. No organism is a pinnacle of FIGURE 2-33 This cladogram is a hypothesis about the ways in which modern plants are evolution. related to each other. At the very base (marked by A) would be the ancestral plants, not much Botanists are working harder than ever trying to fig- different from algae. Many years later, at B, some plants began to evolve into liverworts while ure out how plants are related, which clades are valid. The the rest of the plants continued evolving© otherJones features. &At C, Bartlett some plants began Learning, to evolve into LLCfollowing are the ones you sho© Jonesuld know & as Bartlett you cont inueLearning, LLC mosses, and so on. At some point betweenNOT D and FOR E, vascular SALE tissue evolved OR in the DISTRIBUTION main group into this book. Plants are aNOT clade: FORTrue pla SALEnts orig ORinated DISTRIBUTION of plants, and all plants that descended from these early vascular plants still have vascular from green algae only once. The technical name for plants, tissue as well. That means that the xylem in ferns resembles the xylem in flowering plants to distinguish them from algae, is embryophytes, but not by accident but because both evolved from the same ancestral xylem (to be really careful: The genes that control the development of xylem in ferns and the genes that control the this is used in only the most technical writing. It had been development of xylem in flowering plants resemble each other because both sets of modern suspected that mosses, liverworts, and hornworts might genes evolved© fromJones the same &set ofBartlett ancestral genes). Learning, The lines that show LLC the ancestry of have had a© comp Jonesletely & sepa Bartlettrate orig Learning,in, perhaps the LLCy did cycads, gnetophytes,NOT GinkgoFOR, and SALE conifers all ORstart from DISTRIBUTION the same point (G): That means we do not descendNOT from FOR the sam SALEe ances ORtor tha DISTRIBUTIONt produced all the not yet know which diverged earliest, and we do not know which group is most closely related other plants. But the sequences of nucleotides in the genes to which other group. The line for the ancestry of angiosperms diverges a bit later (H), but it of bryophytes are so similar to those of all other plants could be that this is incorrect and we should draw it coming from G, the same point as the that we are now confident they too are true plants. The cycads and others. terms “vascular cryptogams” and “fern allies” are handy © Jones & Bartlett Learning, LLC © Jonesbut not & Bartlettaccurate. Ear Learning,ly diploid plaLLCnts diverged into two NOT FOR SALE OR DISTRIBUTION NOT clades,FOR SALEboth wit ORh vasc DISTRIBUTIONular tissue and without seeds. One clade, which we call the lycophyte clade (pronounced the common ancestor of all flowering plants was a diploid LIE co fight), was very successful initially and evolved vascular seed plant that made flowers but not cones. At pres- to be large trees with many complex features, but almost ent, we are able to analyze the sequence of nucleotides in the all became extinct. At present, the surviving descendants genes of organisms (we© say Jones that “we & seq Bartlettuence their Learning, genes”) LLCare Lycopodium, Selaginella, ©and Jones a few oth &er Bartlett genera; thes Learning,e LLC and at present we haveNOT sequenced FOR all SALE the genes OR (the DISTRIBUTION entire are the “fern allies” you willNOT see in FORwildflower SALE boo ORks (see DISTRIBUTION genome) of many species. This provides an abundance of Figure 2-30). The second clade was a bit slower at the new information for constructing and testing our theories start, and for millions of years was overshadowed by the and models. abundant members of the lycophyte clade. Many of the The old concept of grades assumed that cycads, ginkgos, early members became extinct, but this clade produced and conifers© Jones were & evo Bartlettlving mor Learning,e slowly than LLC angiosperms all the ferns© andJones seed &pla Bartlettnts. The termLearning, most oft enLLC used and, givenNOT enoug FORh timeSALE, the yOR wou ldDISTRIBUTION finally at long last evolve now is theNOT euphyllophyte FOR SALE clade OR (pronounced DISTRIBUTION you FILL up to the level of having flowers. Similarly, maybe one day in oh fight). The ferns make up a subclade of the euphyllo- the future, ferns would evolve to the point of having seeds, phytes, and they have been very successful without having and so on. It is like moving from grade to grade in school: seeds (see Figures 2-31, 2-32). Ferns thrive in all sorts of Everyone starts out in the first grade and then all move along habitats, not only shady, damp forests, but also hot, dry © Jones &toward Bartlett graduation, Learning, some mov LLCing faster than others, some© Jonesdeserts. & BartlettThey never Learning, produce woo LLCd, so they are all herbs, NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 38 Chapter 2: Overview of Plant Life

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. even the very tall ferns called tree ferns. Some ferns have evolved to have sophisticated relationships with ants, rela- © Jones tionships& Bartlett that Learning,are mutually beneficial.LLC © Jones & Bartlett Learning, LLC NOT FOR SALEThe ferns OR make DISTRIBUTION up a well-defined subclade within theNOT FOR SALE OR DISTRIBUTION euphyllophyte clade, but we are not certain how to group the remaining vascular plants. Many are known only as fossils of isolated leaves or wood or reproductive organs; it is very rare to ever find a fossil of an entire plant with all parts still attached to each other.© Som Jonese espe &cially Bartlett intriguing Learning, fossils LLC © Jones & Bartlett Learning, LLC look like fern leaves withNOT seeds FOR on them, SALE so the yOR were DISTRIBUTION named NOT FOR SALE OR DISTRIBUTION “seed ferns.” But no seed fern is alive today, and no living fern ever has anything that even slightly resembles a seed. We believe that the name “seed fern” was a poor choice, but by now it is very commonly used. The many fossils of seed (A) ferns ©are Jones too incom &plete Bartlett for us to Learning, know if there LLCwas only one © Jones & Bartlett Learning, LLC groupNOT of early FOR seed SALEplants or OR sev eral.DISTRIBUTION If there was only one NOT FOR SALE OR DISTRIBUTION group of seed ferns, then probably seeds evolved just once. If so, all seed plants make up one clade, the seed plants (more technically, spermatophytes). But if seeds evolved two or three times, then “seed plants” is not a clade, not a © Jones &closely Bartlett related Learning,group that all LLCdescended from the same com-© Jones & Bartlett Learning, LLC NOT FORmon SALE ancestor. OR IfDISTRIBUTION seeds evolved several times, “seed plants”NOT FOR SALE OR DISTRIBUTION would then be the name of a grade and could only be used informally. Other extinct seed plants lived after seed ferns. Many look like intermediates in the evolution of modern seed plants from seed ferns, ©but Jones the picture & isBartlett not yet clea Learning,r. Many LLC © Jones & Bartlett Learning, LLC people are taking a cauNOTtious app FORroach SALE now, tent ORatively DISTRIBUTION con- NOT FOR SALE OR DISTRIBUTION sidering all the seed plants as being related. They assume that seed plants evolved only once, and then diverged into sev- (B) eral major groups, most of which have some members that are still alive today. According to this theory (which is the one followed© Jones in this& Bartlettbook), the Learning, early seed pla LLCnts gave rise © Jones & Bartlett Learning, LLC to theseNOT clades: FOR cyc SALEads, gnet ORophytes, DISTRIBUTION Ginkgo, conifers, and NOT FOR SALE OR DISTRIBUTION angiosperms. Until recently, it was thought that all members of the angiosperm clade were either monocots or dicots (FIGURE 2-34). We used to think that after the first flowering plants origi- © Jones &nated, Bartlett the group Learning, immediately LLCdiverged into two distinct clades,© Jones & Bartlett Learning, LLC NOT FORmonocots SALE ORand dicots.DISTRIBUTION But new evidence indicates that spliNOTt FOR SALE OR DISTRIBUTION did not occur immediately. Early flowering plants evolved and diverged into several groups before the monocots originated and became so distinctive. The term “dicot” had referred to all the angiosperms except monocots, but like the term “gymnosperm,” this is unacceptable© Jones because it& does Bartlett not incl udeLearning, all the LLC(C) © Jones & Bartlett Learning, LLC descendants of the commoNOTn ances FORtor of SALEthe group OR (it leav DISTRIBUTIONes out NOT FOR SALE OR DISTRIBUTION monocots). At present, we use the terms basal angiosperms FIGURE 2-34 (A) These avalanche lilies (Erythronium montanum) are shown as representative monocots, but the monocots are a large, diverse group. Many have for those angiosperms that diverged early; monocots for the large showy flowers, although flowers of grasses and sedges are small. Most monocots clade of lilies, palms, agaves, orchids, and their relatives; and have parallel venation in their leaves, and many die back to a persistent subterranean eudicots (pronounced you DIE cots) for all the rest of the angio- bulb or rhizome. (B) These Joshua trees (Yucca brevifolia) are shown as another sperms.© YouJones will sti &ll seeBartlett the term Learning, “dicot” used in LLC many books, representative type© ofJones monocot. Many & Bartlettpeople think of monocotsLearning, as small, delicate LLC and itNOT most often FOR means SALE “basal OR angiosperms DISTRIBUTION plus eudicots.” plants like lilies,NOT irises, crocuses, FOR and soSALE on, but many, OR such DISTRIBUTION as Joshua trees, become Although the terms “dicot,” “gymnosperm,” and “fern very large and tough; other strong monocots are palms, agaves, yuccas, bamboos, allies” are being abandoned, it is good for you to know why and many bromeliads. (C) This lupine, Lupinus latifolius, is shown as a representative they were invented and how they were being used. Even eudicot, but eudicots are a gigantic and diverse group. Of the plants you see every day, though you will still see them occasionally, it is best if you unless a plant is obviously a monocot, conifer, or fern, then it is probably a eudicot. © Jones &avoid Bartlett using them. Learning, LLC © JonesEudicots &can Bartlettbe trees, shrubs, Learning,herbs, vines, parasites, LLC and succulents, as well as many NOT FOR SALE OR DISTRIBUTION NOT otherFOR types SALE of plants. OR DISTRIBUTION Overview of Plant Diversity and Evolution 39

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & BartlettBotany Learning, and LLC Beyond © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION BOX 2-4 Noah’s Flood and Population Biology

The biblical story of Noa© Jonesh’s flood &in BartlettGenesis pro Learning,vided a LLCCould just 12 cattle (clean)© breJonesed rapid &ly Bartlettenough to proLearning,- LLC powerful stimulus for developing the sciences of population duce all the herds and wild cattle on Earth in 1700 ad? Could biology, biogeography, andNOT evo FORlution. SALEVarious bibORlical DISTRIBUTION schol- just two pigs (unclean) be the sourNOTce ofFOR all swine SALE now presORent? DISTRIBUTION ars had studied Old Testament texts, the Jewish Torah, and The first step in answering this was to determine the fecundity archaeological evidence, trying to establish dates such as the of animals: How old do they have to be before they produce birth of Jesus (1 ad, which is 2,017 years ago now) and the their first young? How many young do they produce in each construction© Jones of Solo &mon’s Bartlett temple Learning, (832 bc). Although LLC there is litter? How man© Jonesy survive &long Bartlett enough to Learning, breed? And how LLC many no archaeological evidence, various Bible scholars concluded sets of offspring do they produce in their lifetime? Fortunately that theNOT flood FOR of Noa SALEh occur redOR in DISTRIBUTION 2348 bc. Noah’s flood was it was aboutNOT this time FOR that SALEwealthy lanORdowners DISTRIBUTION began keeping of special interest to early scientists because at that point track of these sorts of numbers for cattle, poultry, fish, fowl, and according to the Bible, all life on Earth had been destroyed even the deer in their private forests. The answer for every type by God except for the creatures in the Ark. Scientists forof animal was the same: Yes, all animals produce young rapidly © Jones &mulated Bartlett the questLearning,ion “Do LLCplants and animals reproduce© Jonesenough & to Bartlett repopulate Learning, Earth in much LLC less than 4,000 years. rapidly enough to repopulate a completely denuded Earth in The early scientists then began to refine their thoughts NOT FORthe SALE time since OR Noa DISTRIBUTIONh?” Thus a scientist posing this questionNOT andFOR reformulate SALE ORthe quest DISTRIBUTIONion. At present we believe in a “bal- in 1700 ad, for example, could assume that Earth had been ance of nature:” Plants capture carbon and energy through repopulated in 2,348 + 1,700 = 4,048 years. photosynthesis, then the plants are consumed by herbivorous First consider the Bible passages that the scientists relied animals or by pathogenic fungi and bacteria. The herbivores on. Genesis 7: 2–3 states© thaJonest God told& Bartlett Noah to takLearning,e seven LLCare eaten by carnivores. If ther© eJones are too &man Bartletty herbivores, Learning, LLC pairs of every kind of “clean animal” (those that could be they damage the plants too much, and some herbivores used for sacrifice; GenesiNOTs 8: 20); FOR only SALEone pair ORof ever DISTRIBUTIONy kind starve, which in turn affectsNOT carnivores. FOR An SALE outbreak OR of DISTRIBUTION a of “unclean animal” (which could not be used for sacrifice); pathogenic fungus that damages plants will cause various and also seven pairs of every kind of bird. Genesis 7: 20 states animals to starve, and so on. The balance between all these that the flood completely covered the tops of all mountains; factors changes from year to year, so the relative numbers that means© Jones that ther & Bartlette was no dry Learning, place anywhere LLC that ani- of organisms© alsJoneso change & yeaBartlettrly. But prioLearning,r to the ana LLClysis of mals could use as a refuge and survive. Although we are all Noah’s flood, people believed that a different kind of “bal- familiarNOT with FOR the rain SALE lasting OR40 days DISTRIBUTION and 40 nights, the Bible ance of nature”NOT was FOR main tainedSALE by ORGod: DISTRIBUTIONGod had created the states that it took a long time for the waters to drain away various carnivores, herbivores, and plants such that plants after the rain stopped. For the early scientists the critical pas- would prosper just enough to supply the herbivores with sages are Genesis 8: 4 and 5 that state that the Ark was float- exactly the right amount of food, and likewise the number ing for 7 months before it settled on Mount Ararat, and it was of herbivores would be perfectly correct for the numbers of © Jones &10 Bartlettmonths befo Learning,re the tops of LLC other mountains were visible© Jonescarnivores & Bartlett in the wor Learning,ld. The balance LLC would be perfect, never NOT FORand SALE Noah ORopened DISTRIBUTION the doors. Especially important was theNOT changing,FOR SALE and wit ORh no DISTRIBUTION waste or shortage unless God specifi- explicit statement that God’s plan succeeded: Genesis 7: 23 cally causes a drought or pestilence. states that everything outside the Ark had been killed. As early scientists studied animal fecundity, they real- In the book of Genesis, God had set up the perfect ized that the numbers did not fit together to make a divinely experiment in population biology. All animals had been balanced system. All organisms are too fertile. If the previ- killed (there is no ment©ion Jones of Noah &nee Bartlettding to colle Learning,ct seeds LLCous interpretation of Genesis ©were Jones correct, & God Bartlett had crea Learning,ted LLC to save the plants), andNOT Earth FORhad to SALEbe comp ORletely DISTRIBUTION repop- plants and animals with the wroNOTng pro FORperties SALE to fit into OR a sys DISTRIBUTION- ulated with all types of animals and birds starting with just tem that would be perfectly balanced and unchanging to the one male and one female of each of the unclean animals end of time. They realized that the story of Genesis as well and just six males and six females of each of the clean ani- as their own research pointed not to a stable, harmonious, mals (Genesis states that Noah sacrificed one male and one garden-like Earth but rather to one of change and competi- female© ofJones each type & Bartlettof clean anima Learning,l after the LLC doors of the tion, of some© orgaJonesnisms & incre Bartlettasing at Learning,the expense of LLC others. Ark wereNOT opened). FOR SALE OR DISTRIBUTION PopulationNOT biology FOR was born SALE and hasOR thrived DISTRIBUTION ever since.

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. ❚❚ Overview of Plant Ecology © Jones Plants& Bartlett live in Learning,a complex, dyn LLCamic, and changing world.© Jones & Bartlett Learning, LLC NOT FOREarth’s SALE complexity OR DISTRIBUTION is easy to see. Some areas are mountain-NOT FOR SALE OR DISTRIBUTION ous with cold temperatures and thin, rocky soil but other areas are low, warm, and moist. Volcanoes release lava and ash that are initially sterile but that gradually change into rich acidic soil. In contrast, limestone breaks down to form alkaline soil. In additio©n, Jonessome soi ls& areBartlett so rich inLearning, certain LLC © Jones & Bartlett Learning, LLC minerals they are toxicNOT and plaFORnts cann SALEot gro ORw on DISTRIBUTION them, NOT FOR SALE OR DISTRIBUTION whereas other soils have a balance of mineral nutrients that encourages luxuriant plant growth. On mountains and in valleys, the slopes that face the equator receive more sunlight and are much warmer than the sides that face away. FIGURE 2-35 This cactus, Stetsonia coryne is at home in Argentina; it is one of many Earth© Jones is dynamic—energetic—for & Bartlett Learning, many LLCreasons. As © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION South American NOTcacti. For almostFOR any SALEcactus you would OR encounter DISTRIBUTION north of the Panama Earth rotates on its axis, a particular area faces the hot sun Canal, there are similar but unrelated species in South America. There were no cacti in during the day but faces the extreme cold of outer space at North America until continental drift brought North and South America close enough night. Throughout a year, seasons change from spring to sum- together for seeds to be carried northward. mer and so on, each characterized by the amount of energy © Jones &available Bartlett from Learning,sunlight. Earth’s LLC atmosphere and its oceans are© Jones & Bartlett Learning, LLC two gigantic fluids that circulate, moving energy from place NOT FOR SALE OR DISTRIBUTION NOT todayFOR are SALE the sam ORe as DISTRIBUTION they were thousands or millions of to place. We experience the circulation as cold fronts of frigid years ago, with the only new activity to ever occur is an occa- polar air that move southward, pushing warm air aside, or as sional meteor strike. But Earth is never the same, not even storms and hurricanes that carry water and energy in such from one year to the next. Mountains are lifted by volcanism concentrated forms they destroy buildings and push over trees. or continental collision, and they are worn down by erosion. Earth’s hot interior© isJones another & sour Bartlettce of energ Learning,y that LLCFlooding rivers carry silt tha©t settJonesles into & richBartlett deltas Learning,and LLC affects life on the planet’s surface. Erupting volcanoes catch NOT FOR SALE OR DISTRIBUTIONmarshlands filled with life. FiresNOT drast FORically alt SALEer the numb OR ersDISTRIBUTION our attention, but Earth’s interior heat also powers continen- of plants and animals in forests and prairies that burn. As tal drift (technically known as plate tectonics): Hot, molten continents drift, their changing positions affect the circula- rock rises along the center line of each ocean then spreads tion of the oceans and thus the circulation of heat and mois- outward as newly-formed sea floor. This pushes the old sea ture. During the time North and South America were widely floor ©to theJones side, which & Bartlett in turn pus Learning,hes continents LLC from place separated, the© Jones Pacific and & BartlettAtlantic Ocea Learning,ns were in LLCcontact to place. North and South America formerly were widely NOT FOR SALE OR DISTRIBUTION and water NOTcirculated FOR aro undSALE each OR cont DISTRIBUTIONinent. But once the separated by thousands of miles, but the continental drift continents collided and formed Central America, oceanic of each changed direction and now they are moving toward each other. Central America is the result of this collision, which is still occurring: North and South America first made contact with each other less than 2 million years ago. As they © Jones &continue Bartlett to pus Learning,h into each oth LLCer, they crumple Earth’s crust,© Jones & Bartlett Learning, LLC NOT FORpushing SALE Central OR DISTRIBUTION America upward and causing numerous vol-NOT FOR SALE OR DISTRIBUTION canic eruptions throughout the region. As the two continents finally came into direct contact, many animals and plants could migrate from one to the other. For example, arma- dillos have been slowly migrating from South America into North America, and hav©e onlJonesy recen &tly Bartlettarrived in theLearning, south- LLC © Jones & Bartlett Learning, LLC ern United States. Unfortunately,NOT FOR sabre-tooth SALE tiger ORs migrat DISTRIBUTIONed NOT FOR SALE OR DISTRIBUTION south, and as they spread into South America, they killed off many large animals, driving many species to extinction. Cacti originated in South America and were confined to just that continent until continental drift finally brought North and South© Jones America & togetBartletther; cact Learning,i could migrat LLCe north into © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION FIGURE 2-36 NOTCreosote bushFOR (Larrea SALE tridentata) isOR at home DISTRIBUTION in the deserts of North Mexico and the deserts of the United States as animals car- America but its closest relative, Larrea divaricata and two other species of Larrea, live in ried their seeds (FIGURE 2-35). The creosote bush that gives South America. The plants in South America resemble those in North America so closely all the deserts of the southwestern United States their dis- that we believe that at some very recent time, a seed or two of L. divaricata was carried tinctive aroma also came from South America (FIGURE 2-36). northward the entire distance and then thrived in the new habitat. Once in North Earth is a changing world. For comparison, think about America, the plants gradually evolved just enough that we consider them to be a new © Jones &our Bartlett moon: It is Learning, complex but notLLC dynamic. The craters we see© Jonesspecies, L.& tridentata Bartlett, distinct Learning,from the ancestral L. LLCdivaricata. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Overview of Plant Ecology 41

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. circulation was altered. Water was forced to flow northward and southward, carrying warm water toward the poles © Jones and& Bartlett making thos Learning,e areas warm LLCer than they had been before.© Jones & Bartlett Learning, LLC NOT FORPlants SALE and ORanimals DISTRIBUTION located in the far northern parts of NorthNOT FOR SALE OR DISTRIBUTION America and Europe experienced climatic warming. Much earlier than that, just before plants evolved from green algae, all continents had drifted together into one gigantic continent called Pangaea (pronounced pan GEE uh). This was so enor©mous Jones that its& Bartlettcenter was Learning,a desert: LLC © Jones & Bartlett Learning, LLC Storms blowing in fromNOT the ocea FORns wouSALEld rain OR them DISTRIBUTIONselves NOT FOR SALE OR DISTRIBUTION out before they could reach the center of the superconti- nent. But because all land was connected, the newly evolved plants could spread easily from place to place such that by the time Pangaea broke apart, each new continent carried some ©plants, Jones and &no Bartlettcontinent wasLearning, left without LLC any plants. FIGURE 2-37 For© mostJones of us, it is & difficult Bartlett to imagine Learning, what Earth was like LLC before the The firstNOT splitting FOR of SALE Pangaea OR ran froDISTRIBUTIONm east to west, creating evolution of trueNOT plants: There FOR was no SALE life on land atOR all. For DISTRIBUTION billions of years, life existed two gigantic continents, Laurasia (North America, Europe, as bacteria and archaeans in the oceans; later there were fish and algae, but nothing Russia, and China in the north) and Gondwana (Africa, at all on land until at the earliest, about 450 million years ago. Most of the surface was rock, and if any soil particles formed, they would have mostly been washed into the South America, India, Australia, and Antarctica in the oceans because there were no plant roots to hold them in place. The area shown here south). Imagine if Pangaea had broken apart before plants is in Death Valley National Park, which does have plant and animal life, but it is widely © Jones &evolved Bartlett from algae.Learning, Plants wou LLCld have originated on one but© Jonesscattered & and Bartlett confined to areas Learning, with at least occasional LLC water. NOT FORnot SALE the other. OR On DISTRIBUTION one continent, plants would have spreadNOT FOR SALE OR DISTRIBUTION and diversified, and would have evolved into many clades. But the other continent would have remained barren until at some point millions of years later, some spores or seeds cyanobacteria, algae, and plants; without these organisms, would have somehow blown or drifted to it (FIGURE 2-37). animals and fungi could not exist. Similarly, as animals and A crucial cause of ©Ear Jonesth being &a chaBartlettnging wor Learning,ld is life LLCfungi respire their food, they ©giv Jonese off carb &on Bartlettdioxide, which Learning, LLC itself. Living organismsNOT take up FOR energ SALEy and nut ORrients DISTRIBUTION from of course is valuable for plants.NOT Thus FOR photosynthetic SALE OR orga DISTRIBUTIONn- soil, water, and air and then release their waste products back. isms have changed Earth such that it is a better habitat for Plants take so much carbon dioxide out of the air that they organisms that respire, and vice versa, organisms that respire have changed the atmosphere. And because carbon dioxide are a source of the carbon dioxide needed by photosynthetic is a greenhouse gas, the changing levels of carbon dioxide organisms (FIGURE 2-38). affect© the Jones temperature & Bartlett of Earth’s Learning, surface—the LLCbiosphere— Plants,© animals, Jones and & all Bartlett other orga nismsLearning, interact LLCin more the placeNOT where FOR life SALEoccurs. Pho ORtosynthesis DISTRIBUTION produces oxygen immediate,NOT direct waysFOR as SALE well. Int eractionsOR DISTRIBUTION may involve one as a waste product that is released into the air. Before the organism benefiting by harming the other (this is preda- evolution of photosynthesis, Earth had no free oxygen at all; tion), by both organisms helping each other (mutualism), by there was no aerobic respiration nor were there any animals. one organism benefitting without harming the other (com- The photosynthetic production of oxygen is carried out by mensalism), and by one organism harming another with no © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

(A) (B) FIGURE 2-38 (A) The grass and herbs here capture energy and minerals, converting them into the organic molecules of the plants’ bodies. Herbivores such as deer eat the plants, using the organic compounds as their own food. The respiration of the animals returns carbon dioxide back to the air; the animal dung also is broken down by fungi, releasing carbon © Jones &dioxide. Bartlett Thus there is Learning, a cycling of carbon dioxide,LLC minerals, oxygen, and other components.© Jones(B) In addition & to Bartlettlarge mammals suchLearning, as deer, insects suchLLC as this caterpillar also consume NOT FORimmense SALE amounts OR of plant DISTRIBUTION material and are an important component of the carbon, nitrogen,NOT and FOR mineral cycles.SALE OR DISTRIBUTION 42 Chapter 2: Overview of Plant Life

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. TABLE 2-6 Direct Interactions among Organisms © Jones &Neutralism Bartlett Learning,Neither organism benefits LLC or is harmed. © Jones & Bartlett Learning, LLC NOT FOR MutualismSALE ORBoth DISTRIBUTION organisms benefit. NOT FOR SALE OR DISTRIBUTION

Predation One organism benefits by harming another.

Commensalism One organism benefits whereas the other is neither harmed nor helped. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Amensalism One organismNOT harms another FOR without SALE receiving ORany benefit DISTRIBUTION itself. NOT FOR SALE OR DISTRIBUTION Competition Both organisms harm each other.

© Jones & Bartlett Learning, LLC FIGURE 2-40 Two© treesJones have died & and Bartlett fallen across this Learning, stream, which keeps LLC their TABLE 2-6 benefitNOT to itself FOR (amen SALEsalism) OR ( DISTRIBUTION). Herbivores and wood moist enoughNOT for moss FOR plants toSALE grow on them. OR The DISTRIBUTIONmosses are benefitting from omnivores are examples of predation. They benefit by eating the presence of these dead trees but the trees are deriving no benefit at all from the plants and this of course harms the plants, so plants need to mosses. Similarly, surrounding trees that are still alive provide shade that is beneficial defend themselves from animals. There is no one single optimal to the mosses, but the mosses provide no benefit to the living trees either. defense; instead many alternative types of defense have evolved, © Jones &such Bartlett as having Learning,spines or being LLC poisonous (FIGURE 2-39). Patho-© Jones & Bartlett Learning, LLC NOT FORgenic SALE fungi OR and bacteriaDISTRIBUTION also prey on plants. NOT TheFOR evolution SALE of OR fleshy DISTRIBUTION, nutritious fruits is similar: Animals Animals often harm plants without benefiting from the benefit by eating the fruits whereas plants benefit from hav- damage they do; this is an amensal relationship. For example ing their seeds disbursed, often in a pile of “organic fertilizer” they trample plants as they walk across them or when they lie (FIGURE 2-41). These cases of mutualism differ fundamentally down. Here too it is beneficial for plants to somehow defend from those of predation and amensalism. In predation for themselves. © Jones & Bartlett Learning, LLCexample, the organisms are bat©tling Jones against & each Bartlett other. When Learning, LLC The presence of treNOTes often FOR creates SALE a shad y,OR cool DISTRIBUTION area in an animal eats a plant, some survNOTiving FOR seedling SALE of tha ORt pla DISTRIBUTIONnt which smaller plants, such as mosses and ferns, can live. The might have a defensive mutation that might make it more shade-loving plants benefit without affecting the trees; this is spiny or poisonous than its parent was. If so, that seedling is a commensal relationship (FIGURE 2-40). more likely to survive and, over many generations, spininess In mutualistic relationships, both organisms benefit. When or toxicity may gradually increase in that species of plant. But animals© Jonespollinate &flower Bartletts, both Learning, the plant and LLC the animal if so, then it© wil Jonesl be helpful & Bartlettto the anima Learning,ls if they hav LLCe muta- benefit:NOT The FORanima lSALE obtains ORnectar DISTRIBUTION or pollen as food, and tions that allowNOT them FOR to overSALEcome OR the plaDISTRIBUTIONnt’s new defenses. plants have their pollen grains carried from one flower to This battle between plants and animals has continued for the others, improving cross pollination and sexual reproduction. hundreds of millions of years that both have existed.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION FIGURE 2-39 This pasture is being overgrown by prickly poppy (Argemone albiflora) FIGURE 2-41 This pile of Texas lignum-vitae (Guaiacum angustifolium) seeds has because cattle and deer will not eat it even if starving. The leaves and stems are passed through an animal, probably a javalina, so all the fruit pulp has been digested covered with spines; it contains a toxic milky juice as well. If there were no herbivores, but the seeds are intact. Five have already germinated. The javalina probably ate the grasses might grow well enough to compete against the prickly poppy and drive it the fruits far from this area and then defecated here, thus spreading the seeds away © Jones &out, Bartlettbut with cattle eatingLearning, the grass, the pricklyLLC poppies have a distinct advantage and© Jonesfrom the & parent Bartlett plant. Both theLearning, plant and the animal LLC benefit in this mutualistic NOT FORmight SALE eventually OR take overDISTRIBUTION the entire pasture. NOT relationship.FOR SALE OR DISTRIBUTION Overview of Plant Ecology 43

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. But a completely new type of evolution began to occur as animal-pollinated flowers evolved. Because plants benefit © Jones when& Bartlett an animal Learning, carries its pol lenLLC to another flower of the same© Jones & Bartlett Learning, LLC NOT FORspecies, SALE any OR mut ationDISTRIBUTION in the plant that helps the pollinator wilNOTl FOR SALE OR DISTRIBUTION be beneficial to both. Similarly any mutation in the animal that makes it a better pollinator helps both itself and the plant. This is called co-evolution and it causes certain plants and animals to become well-adapted to each other (FIGURE 2-42). Keep in mind that at the same time© Jonesthat the pla &nt’s Bartlett flowers are Learning, produc- LLC © Jones & Bartlett Learning, LLC ing nectar that benefits NOTa pollinator, FOR the SALE plant’s leavORes DISTRIBUTION may be NOT FOR SALE OR DISTRIBUTION producing poisons that keep herbivores away. Plants interact with each other. Of course, plants never eat each other; instead plants compete with each other for water and minerals in the soil, for sunlight, and for the © alxpin/iStockPhoto attention© Jones of pollinators & Bartlett and see dLearning, dispersors. In LLC an oak for- © Jones & Bartlett Learning, LLC est, forNOT example, FOR tre SALEes may groORw DISTRIBUTIONso close together that the FIGURE 2-42 OrchidsNOT have FOR extremely SALE complex flowersOR DISTRIBUTIONas the result of co-evolution roots of any one tree touch those of the surrounding trees between each species of orchid and one particular species of pollinator. The benefit of and there is no room for a new oak seedling. Because all the this to the plant is that a pollinator carries the orchid’s pollen only to other flowers of the same species; none is wasted by being accidentally carried to a different species trees are the same species of oak, they probably are almost of plant. On the other hand, if the pollinators die due to a disease or bad weather, the identical genetically and each is about as good as any other orchid then has no alternative means of transferring its pollen. This Phalaenopsis is © Jones &at absorbingBartlett water Learning, and nutrients. LLC Oaks are wind pollinated© Jonespopular in& cultivation. Bartlett Learning, LLC NOT FORso SALE they are OR not compDISTRIBUTIONeting for pollinators. But as mentionedNOT FOR SALE OR DISTRIBUTION before, there are many ways of being adapted so there might be small wildflowers growing between the oaks, wildflowers Because all organisms evolve, a set of organisms such as that can tolerate growing in shade and whose small root sys- a forest never stays the same. At the same time, the physical tems will fit into any spaces between the roots of the oaks. environment also is changing, due both to geological pro- Habitats are complex, so© therJonese may & be Bartlett rocky cliffs Learning, that are LLCcesses and the effects of organisms.© Jones The biosp & hereBartlett is comp Learning,lex, LLC too dry for the oak treNOTes but FORare jus SALEt fine for OR junip DISTRIBUTIONers. In dynamic, and changing. The plaNOTnts, anima FORls, SALEgeology, ORand cli DISTRIBUTION- this forest, the oak trees compete with each other for water, mate that were present in the past were different than they minerals, and light; they make the habitat shady enough for are now, and those of the future will also be different. But for wildflowers, and the junipers are using a resource (rocky studying and understanding life, the process, principles, and cliffs) that oaks cannot. concepts are always the same. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION At the Next Level

© Jones &1. BartlettAlternatives Learning, and consequences LLC. A theme of this book is© Jonesintroduction & Bartlett of Learning,basic principles LLC to the world. However NOT FOR SALEto ask OR “What DISTRIBUTION are the alternatives?” and “What are theNOT FORI recommend SALE OR at thisDISTRIBUTION point that you read Darwin’s Voy- consequences of various alternatives?” Parasitic plants age of the Beagle (1989, Penguin Books), which is his are discussed at several points because they often rep- account of his trip and his collecting. It is written as a resent extremely unusual alternatives to the biology of narrative and is wonderfully easy to read. Darwin wrote non-parasitic plants.© IJones recommend & Bartlett the book Learning, Parasitic LLCit shortly after he returned© froJonesm his voya & Bartlettge, many yea Learning,rs LLC Flowering Plants by Henning S. Heide-Jørgensen (2008, before he had figured out the principles of evolution Brill Academic PubliNOTshers) FOR because SALE it pro ORvides DISTRIBUTION many by natural selection. As youNOT read FOR Voyage SALE of the ORBeagle DISTRIBUTION, interesting examples of highly modified plants and is you will have a better understanding of evolution than well-illustrated. Even as a beginning botanist, you will Darwin did when he was writing it. In certain parts of understand most of it and benefit from knowing how the book, it is fascinating to see how Darwin puts the extreme© Jones certain & Bartlettalternative canLearning, be. You might LLC find it dif- clues together© Jones corr &ectly Bartlett and comes Learning, to key unders LLCtand- ficult to believe that some of these are actually plants. ings using the scientific method. But in other parts, it 2. EvolutionNOT FOR by naturalSALE selectionOR DISTRIBUTION. Charles Darwin and is excruciatingNOT FOR to read SALE as he miss ORes DISTRIBUTIONthe clues and misses Alfred Russel Wallace discovered evolution by natural the point. Voyage of the Beagle is an excellent example of selection in the 1850s, and both evolution and natural how the scientific method is used, how Darwin’s thought selection are dominant themes in this textbook. Darwin processes and reasoning finally allowed him to see the © Jones & Bartlettwrote The Learning, Origin of Species LLC in 1859 and it was the crucia©l Jonesprinciple & Bartlett that is Learning,the basis of all LLC aspects of biology. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 44 Chapter 2: Overview of Plant Life

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. SUMMARY © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR 1. SALEAlmost OR all DISTRIBUTIONplants consist of stems, leaves, and roots.NOT FOR8. A grade SALE is a leveORl ofDISTRIBUTION evolution, and it is an artificial group Flowers and cones are modified stems and leaves. because various unrelated organisms might evolve to 2. One of the defining characters of angiosperms (flowering a particular level independently. A clade is a natural plants) is that their seeds always develop inside a fruit. group because it contains a common ancestor and all 3. The internal organization of plants is very uniform and the descendants of that ancestor. simple; virtually all ©stem Joness have epidermi & Bartletts, cortex, Learning, vascular LLC9. There are multiple ways ©for Jones an organism & Bartlett to be adap Learning,ted LLC tissues (xylem and phloNOTem), FOR and pit SALEh; roots lack OR pit DISTRIBUTIONh; leaves to its environment; there NOTis no single FOR opt SALEimal sol utionOR DISTRIBUTIONto consist of epidermis, mesophyll, and vascular tissues. any biological problem. 4. All plants have a primary body but only woody plants 10. The biosphere is constantly changing due to physical and have a secondary body, which consists of wood and bark. geological forces, as well as to the presence of life itself. 5. All organisms must take in energy and raw materials 11. Organisms interact with each other, often with animals from© Jones their envir & onment;Bartlett the Learning,y also give off LLC waste prod- and fungi© consumingJones & pla Bartlettnts and pla Learning,nts needing to LLC defend uctsNOT to the FOR environment. SALE OR DISTRIBUTION themselves.NOT But FOR som eSALE interac tions,OR DISTRIBUTIONsuch as pollination, 6. All known organisms store heritable information in DNA. are mutually beneficial to both plants and animals. Plants 7. Plants detect and respond to information from the envi- also compete with each other for various resources. ronment as well as from various organs within the plant itself. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

IMPORTANT TERMS © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC angiosperm Gondwana reproductive organ basal angiosperm NOT FOR SALEgrade OR DISTRIBUTION respirationNOT FOR SALE OR DISTRIBUTION biosphere gymnosperm seed plant clade herb spermatophyte common ancestor Laurasia spore-bearing plant cormophyte© Jones & Bartlett Learning,lycophyte LLC clade © Jonesthallophyte & Bartlett Learning, LLC cryptogam monocot thallus dicotNOT FOR SALE OR DISTRIBUTIONnonvascular plant NOT FORtracheophyte SALE OR DISTRIBUTION embryophyte Pangaea vascular plant eudicot phloem vegetative organ euphyllophyte clade photosynthesis woody plant fern plant xylem © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

REVIEW QUESTIONS © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 1. Name the three vegetativeNOT FORorgans SALEof a plant. OR DISTRIBUTION6. ______NOT is theFOR centra SALEl meta ORbolism DISTRIBUTION 2. How do the reproductive organs of ferns differ from by which plants acquire energy; it occurs only when foliage leaves? ______, ______, 3. Name the four basic organs of a flower. Describe situ- and ______are present. ations in which flowers might not need one or two of 7. Each plant receives a great deal of information from these© Jones organs. & Bartlett Learning, LLC its parents© Jones by mea &ns Bartlettof the DNA Learning, in which two LLC cells? 4. NameNOT the FOR two vascSALEular tisORsues DISTRIBUTION found in vascular plants. DescribeNOT the FORtypes ofSALE information OR DISTRIBUTION that plants receive What does each transport? from the environment. Why is it that environmental 5. Are there any types of organisms that do not need to information cannot be stored in DNA? take in energy and raw materials from their environ- 8. The activity of the roots of a plant must be coordinated ment? Discuss the source of energy for plants as opposed with the activity of leaves. Describe how this occurs. © Jones & Bartlettto animals; Learning, describe som LLCe of the raw materials that are© JonesWhat & Bartlett type of information Learning, molecule LLC is used? NOT FOR SALEneeded OR by plants.DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Review Questions 45

© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. 9. Which three groups of plants are referred to as bryo- has thousands of plants adapted to the Amazon Rainfor- phytes? They differ from all other plants in two main est; do you think it is likely that any of those plants will © Jones & Bartlettfeatures; name Learning, the features. LLC © Jonesbe & able Bartlett to migrat Learning,e to North Amer LLCica across the deserts NOT FOR10. SALEWhich OR group DISTRIBUTION of plants does the term “angiosperm”NOT FORof Mexico,SALE Texas, OR DISTRIBUTIONand Arizona? refer to? What are the three main subgroups of angio- 13. The concept of biosphere was touched on only briefly in sperms? Do angiosperms have vascular tissue? Do they this chapter, but you have many resources in this book have seeds? In conifers, seeds develop inside cones, and online to explore this concept. What are some of but in angiosperms, seeds always develop inside of the geological and biological components of the bio- ______. © Jones & Bartlett Learning, LLCsphere? We humans are burnin© Jonesg fossi &l fuel Bartletts and adding Learning, LLC 11. Evolution by naturalNOT sele FORction SALEcauses orgaORnisms DISTRIBUTION to carbon dioxide to the atmNOTosphere; FOR how SALE does this OR affe DISTRIBUTIONct become more adapted to their environment. Is the envi- the biosphere? ronment uniform across all of Earth? Does the environ- 14. Plants and animals usually battle each other; describe ment change with time? Considering this, do you think why and how this occurs. Once animal-pollinated flow- that there is only one single optimum way for a plant to ers evolved, a new type of plant–animal interaction was be© adapted? Jones If & not, Bartlett what is the Learning, alternative? LLC possible;© describe Jones it. & How Bartlett is it possi Learning,ble for a mutation LLC in a 12. HaveNOT North FOR and SALE South AmerOR icaDISTRIBUTION always been connected plant toNOT be beneficial FOR forSALE both the OR pla ntDISTRIBUTION and for an animal? by Central America? Once the two continents joined, 15. Earth is constantly changing, and so are all organisms plants and animals could move from one to the other; as they evolve. But despite so much change, it is possible animals can walk, fly or swim, but how does a plant spe- to study and understand life because several things are cies spread from one area to another? South America always constant; what are those things? © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Design Credits: Hummingbird: © Tongho58/Moment/Getty; Green plant cells: © ShutterStock, Inc./Nataliya Hora; Purple tulip: © ShutterStock, Inc./Marie C Fields; Dandelion: © ShutterStock, Inc./danielkreissl; Poppy: © ShutterStock, Inc./Saruri; Plant icon: © ShutterStock, Inc./Vector; Digging man icon: © ShutterStock, Inc./Z-art