teacher : The Basics of

what is a ? I : flowers attract and provide while completing the needed process Although this may seem like an easy answer, a of . plant may be defined differently depending on I : fruits protect and disperse the group the people. An elementary school teacher inside. may describe a plant as a “living green thing”, a high school teacher may narrow this definition, I Seeds: Seeds are young that continue and a plant may have a technical un - the lifecycle. derstanding of a plant. All these definitions serve a purpose and the definition needs to be what are the parts of a plant? modified depending on the audience. The plant can be divided into three main Plants are “green things”, which means they carry parts: , stems, and . Some botanists out a process called . There are refer to the latter two as “”. Most many green, photosynthetic , but students have a good understanding of what some of these, such as , are not plants. these look like, but the distinction between are a group of organisms that may be these can sometimes be fuzzy. considered plants by some teachers, but would Consider that some plants have stems that be called by . This distinction is resemble roots (e.g. ), or stems that probably not important to school children; the resemble leaves (e.g. prickly ). It is important message is that these organisms use important that students understand that plants the sun to make their own . In contrast, a need certain materials to survive; these may be group such as fungi, although plant-like, do not obtained by roots in some plants but through make their own food and should not be consid - the stems or leaves in another. The determina - ered plants. For the purposes of this handout, we tion of whether a plant part is a or stem, will concentrate that live on and such as the , seems to be less important. are familiar to students of all ages and levels. The flexibility, adaptability of plants and the Defining Characteristics of their parts should be the focus. I Roots: absorption of and ; anchorage of plant to the ; usually found underground I Stems: support of leaves, flowers, and fruits; transportation of water –minerals from roots to leaves; found above and below ground. I Leaves: site of photosynthesis or food-mak - ing; usually found above ground.

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what are roots? I Respiration : Some swamp or flooded plants Roots serve as the most fundamental to produce roots or “knees” that grow up and out health of most plants. The root or is the of the water, allowing the roots to exchange first plant part to appear from a . Roots act to gases in this -free environment ( e.g . bald anchor the plant and absorb water and cypress, ) for photosynthesis; these are called true roots. I Support : Specialized adventitious roots called True roots are usually divided into two forms: prop, stilt, and buttress roots can be found on fibrous and tap . Some plants have a mass of tropical that experience frequently string-like, fibrous roots ( e.g . grasses); others flooding ( e.g . mangrove). have a large, main with smaller side roots I Photosynthesis : In rare cases, plants have (e.g . , ). Sometimes roots “sprout” green, aerial roots that photosynthesize from the side of a stem, like in a ; these are (e.g . orchids). called adventitious roots. A plant with an will have adventitious roots. Functions of roots what are stems? I Absorption : Absorption of water and nutrients Stems are the most basic organs on plants. are one of the primary functions of roots. Roots Simple examples of a stem are twigs, , absorb water through a passive, physical process. and the (s) of a . Stems can range Water being released from leaves is linked to from hard & woody to soft & green other water in the plant like a chain. (herbaceous) , but almost all stems serve a As the water is pulled out of the into the at - supportive function on a plant. mosphere, the chain pulls new water molecules Most people know what a stem looks like, but up through the stem and into the roots. some plants make the distinction difficult. I Anchorage : Roots also act to anchor the plant Some plants have small stems, or underground in the soil or on rock. Thus, roots act as the stems () , or leaf-like stems, or stem- major supportive organ for all other organs. like leaves or sometimes lack stems altogether. I Conduit : Roots (like stems and leaves) serve as Although we make neat and clear categories the initial pipeline for water that is needed in the called stems, leaves, and roots, this distinction plant. () are also transported down can be blurred. Grasses are a good example in to the actively growing portions of the root. which the difference between leaf and stem is not easily observable. I Storage : Most roots store some quantity of sugars, water, or toxic chemicals (like leaves and stems), but some roots are quite large and fleshy storage organs ( e.g . carrots).

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what are stems? (continued) I Protection : In many plants, branches have been modified over to serve as protection Functions of stems against large animals; these are called thorns. Many trees have thorns ( e.g . hawthorn, crabap - I : Most stems serve the role of support in a plant. For example in a tree, the trunk sup - ple, locust). Note: Cacti and bushes ports the branches, which support the twigs, do not have thorns, because these are not mod - (see leaves & hairs below). which support the leaves, flowers, and fruits. In ified branches non-woody plants (“”), there is no trunk. I Clonal growth : Many plants have stems that Instead, these plants have soft, green stems that can creep on top () or under the ground support the leaves, flowers, and fruits. () producing new “plantlets”, which are clones of the parent. Although common in I Transportation : Stems serve to transport the e.g materials needed in photosynthesis. Inside a herbaceous plants ( . , crabgrass), stem there are tissues called and . some trees also exhibit clonal growth. These Both are tubes that transport materials through trees are said to have “suckers” growing from e.g the plant: xylem water and sugars, respectively their base ( . crabapple, ). (see xylem & phloem below) . I Storage : Many stems store food, water, and what are leaves? waste products. An example of a storage stem is Many leaves are composed of three parts: the the white potato ( tuberosum), which blade , the , and . The blade is could be called a . Food and water storage the flat, wide, photosynthetic part of the leaf. in common in arid conditions. Plants cannot The petiole is the thin stalk that holds the blade easily get rid of harmful chemicals from the air and attaches the leaf to the stem. Stipules look and soil; therefore, they store these chemicals in like tiny leaves that are found at the base of the special cells. petiole; they are not always present. An I Photosynthesis : Almost all plants have stems leaf has a clear example of blade and petiole, that can photosynthesize. Some plants have but grass leaves have blades only. Both are stems that are always green, such as cacti and example of simple leaves, because the blade is palo verde. Other plants, such as oaks, just use entire and not split/sectioned into leaflets. A their young twigs and leaves for photosynthesis. leaf that is segmented into leaflets is called a compound leaf. I Protection : against large animals; these are called thorns. Many trees have thorns ( e.g . Discerning a leaf from a leaflet, and thus a sim - hawthorn, crabapple, ). Note: Cacti ple from a compound leaf, can be challenging. and rose bushes do not have thorns, because The simplest way is to look at the intersection these are not modified branches (see leaves between the “stem” and the base of the “leaf”. and hairs below). If there is a at this location, then you are

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what are leaves? (continued) that wrap around other plants, fences, wire, etc. for support. observing the attachment of a leaf to a stem. I Protection : In many plants, leaves have been If the bud is missing, then you are looking at a modified to a sharp point to serve as protection: leaflet attached to a larger, compound leaf. spines. Many arid-adapted plants, such as cacti, All leaves have stomates, which are pores in have spines. the leaf, with guard cells that regulate the exchange of gases and water vapor with the what are flowers? environment. These stomates can be opened and closed to regulate the of the Flowers are beautiful that are com - plant. Oaks, like many trees, have stomates posed of many parts. The forms in a only on the bottom of their leaves; grass leaves bud, and emerges on a short stalk or stem. have stomates on both sides. The end of this stem has four different parts: , , , and pistils. Each part Almost all people know what a leaf looks like, has a specific function (discussed below) that but contemporary leaves can range from will ultimately lead to fertilization of new microscopic (water : ) up to 83 seeds. feet long (Raphia palm). A group of flowers is called an . Functions of leaves To understand the difference between a flower I Photosynthesis : The leaves of almost all plants and an inflorescence, compare the following photosynthesize. is used to convert examples. The largest flower in the world is the dioxide and water to sugars and oxygen. stinking corpse lily ( arnoldii ); flowers I Conduit : Just like stems/roots, there are can reach 3ft across and weigh 15lbs. The portions of leaves that transport water and largest inflorescence is from the talipot palm sugars to and from, respectively, those areas ( umbraculifera ), which can reach 30ft of photosynthesis. tall with millions of flowers. I Storage : Many leaves store water, sugars, and Parts and functions of flowers toxic materials. Some desert plants are succu - I Sepals : The sepals are usually green, thick and lent in which they store water in their leaves. very leaf-like, but in some cases ( e.g . , Food storage is common in underground leaves, lilies), they -like. Sometimes a mature such as the fleshy, edible leaves of the flower lacks sepals all together. If present, . Many plants can store toxic chemicals in sepals are the lowest most part on the flower. leaves, and then drop the leaf when “full”. Sepals serve as a of scales that protect the I Support : Many have modified leaves unopened flower. called , which are thin, stem-like leaves

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what are flowers? (continued) what are fruits?

Parts and functions of flowers (continued) Fruits are, by definition, the mature, seed-con - I Petals: The petals are usually colored, thin, and taining of flowers. We sometimes use leaf-like in appearance. The petals are above the the terms “” and “”, which are fre - sepals on a flower. Plants that are -polli - quently confused. The term “fruit” is a botanical nated usually do not have large, showy petals. term ( after fertilization), but “vegetable” The main function of the petals is to attract is not. For simplicity, any plant structure that (, , or mammals). contains seeds is a botanical fruit; those edible plant parts that are roots, stems, or leaves I Stamens: Above the petals are the male or could be considered . Some plant -producing parts. The stamens can range parts may be a plant’s fruit, but a grocery store in size and shape, but most are composed of vegetable ( e.g . ). two parts: the anther and the filament . Some animals collect pollen for food ( e.g . ), but Fruits come in a wide variety of shapes, sizes, others feed on different parts of the flower and colors, but not all fruits are edible to hu - (e.g. nectar). The main function of the anther is mans or other animals. The smallest fruit be - to produce pollen (the “male” part of the plant). longs to the smallest plant, the waterweed The filament’s function depends on its shape (Wolffia ), which has fruits the size of a salt and size. . The largest fruit on record is something in the ; specifically a that I Pistils: The innermost part of the flower is the weighed 1,300 lbs. The largest fruit from a tree pistil, or the portion of the flower. A pistil is the ( heterophyllus ), is the composed of three parts: ovary, style, and which can weigh up to 75 lbs. . Inside the ovary are or pre- seeds, which are unfertilized seeds. The stigma Functions of fruits is the landing-pad for the pollen, and the site of I Protection: Fruits are a plants way of pollination . The style is a thin stalk that raises protecting their young: the seeds. the stigma up so it can catch the pollen. After I Dispersal: Fruits disperse their seeds through fertilization, the ovary becomes a fruit. As this a variety of methods. Fruits are commonly fruit grows and matures, many other flower thought of as large, juicy structures, such as parts like petals and stamens wither and fall off. , , or , but they can be dry and hardened structures as well.

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the height record breakers, such as the red - what are seeds? of California ( sempervirens ), which can reach almost 400 feet tall. Seeds are baby plants, or the fertilized ovules of a plant. Seeds come in a range of size and Tree-like plants: Many monocots and some shapes. The smallest seed belongs to orchids, reach tree size and stature, such as palms, which can been dust-sized and weigh as little , and tree ferns. Botanists as 0.0000035 oz. The largest seed comes from avoid calling these plants “trees”, because they the coco-de-mer or “double ” palm do not contain . Woody trees increase in ( maldivica ), which can be 12 in long, girth over time, but these plants remain the and weigh up 40 lbs. In every , same width from top to bottom. Therefore, seeds are born in fruits they use roots, leaves and other features to support their height. Functions of seeds or bushes: Similar to trees, shrubs are I Protection: The seed seems to have evolved plants that are small and woody. Unlike most as a way to protect the from the envi - trees, shrubs produce many smaller stems than ronment; a seed allows the plant young to sur - one large trunk. Shrubs may grow in full sun as vive dry or harsh condition for short periods. a successional , or as a -tolerant I Dispersal: Besides the fruit, some seeds have plant in a . Shrubs are usually dicots. special features that aid in their dispersal by Vines and : Unlike the other plants , wind or water. mentioned, vines and lianas obtain by I Warning: Some seeds are poisonous and ex - growing up on top of other trees or structures. hibit a coloration pattern that warns animals; Vines are usually herbaceous, but lianas are these seeds do not need an animal disperser, woody. Young vines are adapted to low-light, and use other dispersal methods. but mature plants are usually in full-light of the tree . This form exists in dicots, what examples of plant form exist? monocots, and even ferns! Most students can recognize that plants come Herbaceous plants or herbs: Plants that are in many different heights, widths, and overall soft and green are called herbaceous. is forms. Below is a listing of some of general short for herbaceous, but we usually think of plant forms that exist in the world. fragrant plants used for cooking. These plants are usually small or smaller than trees. Ferns, Trees: Plants that are large or tall and possess grasses, tulips, and most vegetable are wood are considered trees by botanists. Trees examples of herbaceous plants. may be shade-tolerant or prefer full sun. These are usually flowering dicots or cone-bearing . True trees (vs. tree-like plants) are

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