4/12/16

Week 2; Monday

Announcements: Arb field trip next week on Th, Fr, Sat; sign up for a time this week or next. First lab quiz next week on Wednesday

Plant - form or structure of a and its parts

Plant Anatomy - cell and structure of a plant

Vegetative morphology - any portion of a plant that is involved in growth, development, , support, etc., but NOT involved with . Example: , stems, , , etc.

Lecture: Vegetative Morphology (to be delivered by TAs in lab)

Reproductive morphology - any portion of a plant that is involved with or a direct product of sexual reproduction Example: , , seeds, etc.

Vegetative Morphology [see web lab exercise; Judd et al. 55-63]

Seed The contains a young plant in which development is arrested and the plant is dormant. From the seed emerges a stem, or plumule, and a primary , or radicle. Food is stored in the seed in the (3n) or in the cotyledons.

Roots If the primary root persists, it is called a “true root” and may take the following forms: taproot - single main root with small lateral roots fibrous roots - many divided roots of +/- equal size. If the primary root dies (or even if it persists in some ) new roots may arise from the stem. These are called adventitious roots. All roots on monocots are adventitious roots

Stems At the tip of the growing is a terminal or apical bud. A bud has bud scales surrounding it to protect the developing parts inside. Inside a bud are primordia, lateral bud primordia, and the apical . The apical meristem is responsible for new terminal growth.

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Below the terminal bud regions of the stem may be identified as follows: node - point of attachment of a leaf lateral bud - always found in the axil of a leaf (between the leaf and stem, upward on the stem from the point of attachment of the leaf) internode - region of the stem between two nodes.

Modified stems: - underground laterally growing stem (ginger) - swollen elongate ; modified rhizome (potato) - underground stem with many swollen leaf bases surrounding it (onion) - swollen round underground stem (many flowering ‘’) – ‘runner’ or rhizome above the soil (strawberry plants)

Leaves At the point of attachment of the stem to the leaf there sometimes is a small leaf-like structure attached to the stem called a stipule Leaf structure: blade - the broad part of the leaf - the slender part of the leaf that attaches the blade to the stem margin - the edge of the blade; may be smooth or variously shaped ribs - vascular bundles or veins in the leaf; the central one is the midrib Leaf Shape: simple - undivided blade compound - blade divided into leaflets, each resembling a leaf; a leaf may compound more than once. You can tell a compound leaf from a simple leaf, by looking for an axilary bud at the point of attachment of each blade. If you find one the leaves are simple, if not, they are compound (there should be one at the base of the compound unit, however). dissected, or divided - blade lobed, but not all the way to the midrib. pinnate - veins arranged like “pinnae” on a feather palmate - veins arranged like fingers radiating from the ‘palm’ of your hand Leaves may be pinnately of palmately compound, however when there are three leaflets it may be impossible to tell which. In that case the leaves are called ternate. Venation (arrangement of veins) - net veined - a branching, divergent and often reticulate pattern may be palmate or pinnate - parallel veined - primary veins all parallel as in grass Leaf Arrangement (attachment of leaves to stem) Alternate – one leaf per node Opposite – two leaves per node on opposite side of stem Whorled – more than two leaves per node

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Reproductive Morphology [Judd et al. pp. 61-67; 72-81]

Angiosperms (“clothed seed” plants) are characterized by the presence of flowers and, more specifically, the presence of a structure called a carpel which encloses the seed Flowers consist of a series of parts that are modified leaves. Goethe (Germany; 1749-1832) – suggested that parts are modified leaves (1790 in “Metamorphosis of Plants).

Flower Parts – modified stem leading to the flower – end of stem on which flower is borne - outer (lower) of parts; often greenish - function to protect, photosynthesize, attract calyx - collective term for sepals of one flower – second whorl of parts; often colorful - function to attract pollinators, but often missing in wind-pollinated plants corolla - collective term for petals of one flower

Perianth – collective term for calyx and petals – term used for sepals & petals when they look alike - producing structures - provide ‘male’ function in reproduction (pollen = male, or microgametophyte; are produced here) - consist of long filament supporting the anther, where pollen is produced androecium - collective term for ‘male’ portion of flower carpel - producing structures ( contain the megagametophyte; are produced here) consists of swollen at base, elongate style supporting the at the tip, where pollen is deposited - provides ‘’ function in reproduction ovule - the -producing is contained in this structure placenta - tissue lining the ovary that bears the ovules

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Now here’s where it gets confusing: Flowers may have a single carpel or many carpels; the carpels may be separate or fused together pistil - generalized term for each individual female structure in a flower When single or separate, each carpel equals one pistil – simple pistil There may be one or more than one simple pistil per flower When fused together, one pistil may consist of many carpels - compound pistil There may ONLY be one compound pistil per flower

How can you tell if a pistil is simple or compound? There are two ways to tell that will work in almost all cases. 1) Look for more than one stigma lobe at the top of the pistil; compound pistils often have separate styles or lobes on the stigma. 2) Make a cross-section of the ovary and look for compartments (locules), or more than one point of attachment of the ovules, that indicate fusion of two or more carpels. - collective term for ‘female’ portion of flower (may be one or many pistils) *** In nature, there are plants with one or more simple pistils and plants with one compound pistil, but no plants with more than one compound pistil per flower. ***

Inside the ovary the ovules attach to the placenta in two basic ways: parietal placentation - ovules attached along the ovary wall “primitive” carpel a folded megasporophyll with ovules along fused margins axile placentation - ovules attached to a central septum in the center of the ovary

Variations on axile placentation include: free central - axile with the septum missing basal - derived from either axile or parietal, but only attaching at the base

Locule – The chamber or opening inside the ovary where the ovules are found. There is not really empty space here (although sometimes a space develops as the seeds mature in the ), but the ovules are only attached to the ovary wall at the placenta, thus the locule is a chamber filled with ovules.

Flowers may be: complete - all four whorls present incomplete - one or more whorls missing perfect - both reproductive whorls present (bisexual) imperfect - one reproductive whorl missing (unisexual)

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Plant species may be: hermaphroditic – plants with perfect flowers monoecious - plants with imperfect flowers, in which both are on the same plant dioecious - plants with imperfect flower, in which each is on a separate plant

In many flowers the parts in each whorl or the whorls themselves may be fused together connate - parts of one whorl fused to each other gamopetaly or sympetaly - fused petals syncarpy - fused carpels adnate - parts on one whorl fused to parts in another whorl epipetalous stamens - stamens adnate to petals

The position of the ovary relative to other flower parts is often diagnostic: superior ovary – hypogynous (‘hypo-‘ means ‘under’ and refers to location of other parts relative to the ovary inferior ovary – epigynous (‘epi’ means ‘over’) sometimes there is a fusion of parts at the base of the flower that makes it unclear where the ovary is relative to the attachment of the other parts and it may appear to be anywhere between fully superior and fully inferior this situation is called perigynous (‘peri-‘ means ‘around’)

Flower symmetry - Radial, regular, or actinomorphic symmetry - many planes of symmetry bilateral, irregular, or zygomorphic symmetry - one plane of symmetry

Inflorescence - term for the flowering part of a plant; all of the flowers in aggregate Infructescence - after flowering is over and the fruits have ripened.

Fruit - mature ovary - once the eggs within the ovules have been fertilized and the ovary starts to expand, it is usually called a fruit functions: [one or more of these may exist for same fruit] dispersal of seed nutrition for developing protection of seeds prevent being eaten

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Week 2; Wednesday

Announcements: Next week - quiz on and plant structure; Arb field trip Props for lecture today: with ; sword frond with sori

Lecture: Keys, Life Cycles and Major Land Plant Groups

Dichotomous Key - a progressive series of paired alternative statements that lead to the identification of an organism. - keys don’t need to be dichotomous, but usually are - written keys start with a certain bit of information and progress towards an end - computer keys (only now coming into use) can start with any information - Usually most useful keys are artificial, in the sense that if you draw a dichotomous reflecting the branches in the key, the branches would not be monophyletic groups - leads may pair “this” vs. “that”, or may pair “this” vs. “not this” - read carefully - if more than one character is described in key lead, the most important or consistent difference usually is listed first.

Review Reproductive morphology – answer questions (esp. carpel/pistil terminology)

Reading from J. W. Krutch, pp. 165-67 in The Voice of the Desert.

Lecture: Life cycles and Land Plant Relationships Life Cycles (... of the rich and famous) [web readings 6-7]

Generalized life cycle -overhead- (see below) - alternation of generations – emphasize continuity - life is like a sine wave...

Fertilization – the act of fusion between sperm and egg. Fertilization occurs in all sexually reproducing organisms In seed plants, this must follow .

Sporophyte – the diploid (2n) generation in plants. It begins with fertilization, which produces the , the first cell of the diploid generation. () produces the and, ultimately, the mature , which makes special structures called sporangia, where takes place. – the product of meiosis; the first cell in the haploid (1n) or gametophyte generation in plants. Gametophyte – The haploid (1n) generation in plants. Flowering plants are heterosporous, meaning that they produce two different kinds of : 1) the becomes the pollen grain and 2) the becomes the embryo sac. These are called the male and female , respectively. Pollination – the act of transferring pollen (male gametophyte) from anther or male cone to stigma or female cone; restricted to seed plants.

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Gamete – the haploid cells that participate in fertilization, egg and sperm. These are produced by specialized structures in the gametophyte generation of plants called archegonia and antheridia, respectively (collectively called gametangia). In flowering plants the gametophytes are so reduced (pollen grain and embryo sac) that distinct gametangia are not found.

NOTE: In most animals the product of meiosis also functions as a .

Distinguish Pollination from Fertilization and Spore from Gamete

mature sporophyte

embryo diploid (2n) sporophyte zygote generation Fertilization Meiosis haploid (1n) gametophyte spores (egg and sperm) generation

Archegonium

mature gametophyte

Variations on the theme .... Each generation (sporophyte/gametophyte) may be: Free-living – depending only on itself for nutrients Dependent – depending on its parent (previous generation in the life cycle) for nutrition Usually one generation is dominant, but in some both are +/- equivalent. - some have sporophyte dominant, some gametophyte dominant, and some are isomorphic - gametophyte dominant and free-living; sporophyte dependent - sporophyte dominant and free-living; gametophyte free-living, but small and short-lived seed plants - sporophyte dominant and free-living; gametophyte dependent and reduced Angiosperms - gametophyte VERY reduced - pollen 2-3 cells; embryo sac 8 cells

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Land Plant Relationships -Overhead-

Major groups of organisms in Kingdom Plantae (= green plants)

Note that this is one view of land plant relationships. Some molecular evidence contradicts this view, suggesting that ‘’ might be related differently than shown here. Also, some evidence suggests that the extant (those alive today) ‘’ may be monophyletic.

Plantae “Green Algae” - paraphyletic basal group Land Plants Liverworts \ > “Bryophytes” paraphyletic - consists of 3 monophyletic groups Mosses / Tracheophytes (traditionally “vascular” plants, However, mosses have vasculature, but not special cells called ‘tracheids’) - (club mosses), (resurrection plant) Fern allies Sphenophytes - (horse tails) Ferns - Seed Plants Ginkgo Conifers - you know these guys Gnetophytes - , Ephedra (Mormon Tea) , Angiosperms – the rest of the quarter will be about these guys note that there is a relative time line on a cladogram, with the tips being the present

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Land plant relationships and derived traits (synapomorphies) of major groups

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Week 2; Friday

Announcements: 1) First lab quiz next Wednesday on conifers and plant structure 2) First lecture exam in 2 weeks it will cover material through next Friday 3) Next week will be a field trip to the Arboretum; sign up for a time next week in lab

Angiosperm Classification

Many classifications have been proposed over the years. We generally start with Linnaeus (Species Plantarum 1753), but there were others before him.

Engler and Prantl (Die Naturlichen Pflanzenfamilien, late 1800’s) treatment included 280 families and is the basis for the formal organization of most herbaria around the country today. -- Later in lab we will visit our --

Bessey (early 1900’s) was the first American to propose a system and his was the starting point of many subsequent systems, including Cronquist and others.

These are all what we call “authority-based” classifications [OVERHEADS]

Stebbins 1974 \ Cronquist 1981 \ Takhtajan 1987 ----OVERHEADS Dahlgren 1989 / Thorne 1992 /

What about now?

New classifications are not authority-based classifications, but are based on phylogenetic reconstructions, which are derived from commonly agreed-upon principles and objective data.

Our current view of relationships is derived primarily from the results of the analysis of DNA sequences from the genome primarily, but increasingly from nuclear and mitochondrial genes, as well. Mitochondrial genes have been used to a much greater extent in animals. e.g., Chase et al. 1993. – OVERHEAD; APG III – OVERHEAD

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Monophyletic origin of angiosperms. Evidence: 1) Carpel (ovary) enclosing the ovules 2) Ovules with two integuments (bitegmic ovules); integuments surround the ovule and become the seed coat) 3) Reduced female gametophytes (embryo sac) (typically composed of 7 cells and 8 nucleii - the two polar nuclei occupy the same cell) 4) Triploid endosperm product of (sperm + 2 polar nuclei) 5) Sieve tubes in their phloem to conduct fluids from leaves to other parts of plants Sieve tubes have open ends and stack like straws inside the plant

Within angiosperms two features may each be used to divide them into two groups: 1) Number of cotyledons (seed leaves) - one or two (monocots and dicots) 2) Number of apertures on the pollen grain - one or three (basal angiosperms and tricolpates, or sometimes called ‘eudicots’) - OVERHEAD

However, neither character splits the flowering plants into two monophyletic groups and there are some families that are left out of the groups characterized by the derived states of one cotyledon and tricolpate pollen.

It is important to point out that many details of the relationships among flowering plants remain unresolved

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However, some important groups do emerge (OVERHEAD): The most primitive plants may be either herbaceous or woody. These all have monocolpate pollen and two cotyledons: 1) Near the base of the tree are three groups of plants that are or herbs, including (one sp. from New Caledonia), Nymphaeales (water lilies), and a few odd genera from around the world sometimes called the “ANITA grade” (or “ANA” grade in Judd et al. 4th Ed.).

2) Also near the base are some woody plants called the Magnoliales and Laurales

3) The remaining basal groups (including Piperales and Chloranthaceae) are mostly herbaceous. Along with the water lilies and monocots, these sometimes are called the “paleoherbs”

4) Monocots are monophyletic and derived from dicots - some shared derived characters include: single cotyledon scattered vascular bundles parallel leaf venation (or striate venation, sensu Foster and Gifford; note exceptions in some monocots However, they do have pollen with a single aperture.

5) Another important split occurs between the monocolpate and tricolpate pollen types; the latter are called Tricolpates (more commonly called Eudicots). Within the Tricolpates; there are three large monophyletic groups and several small groups at the base: 5a) “Basal Tricolpates” is a basal paraphyletic group within the Tricolpates

5b) Caryophyllids - This group is pretty well characterized by some distinctive features, including pigments known as betalains and seed nutritive tissue called perisperm. Flowers are polypetalous

5c) Rosidae sensu lato - contains most of the polypetalous families. This group is difficult to characterize; mostly by absence of traits found in other groups

5d) Asteridae sensu lato - contains most of the gamopetalous families (with connate petals fused into a tube around the rest of the stamens and pistil) these are characterized best by embryonic and chemical characters - tenuinucellate ovules (a thin nucellus) - single integument on the ovules (one has been lost, or the two are fused) - secondary chemical compounds known as iridoids

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Magnoliidae"

sca1ered"vascular" """""bundles" parallel"vena/on" 1"cotyledon"

Perianth"of"2"whorls" Anthers"well"differen/ated"from"filaments"

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