Review of the previous lecture Phylogeny Phylogenetic trees ingroup; outgroup; sister relationship; most recent common ancestor; monophyletic, paraphyletic, and polyphyletic groups; Character homology; synapomorphy; symplesiomorphy; convergent character; Phylogenetic reconstruction Phylogenetic classification
The tree thinking challenge (clarification) Taxa that share a MORE recent common ancestor are MORE closely related to each other Think about your family genealogy (family tree)
Phylogenetic reconstruction: Principle of parsimony Characters Taxa a b c outgrp 0 0 0 1 0 1 0 2 1 0 1 3 1 1 1 parsimony - (Occam's Razor) - the principle that the explanation requiring the least change is preferred. out 1 2 3 b b c a out 1 3 2 b a c a c out 1 2 3 b a c b a c 4 steps 5 steps 6 steps
Inferring phylogenies using DNA sequences: real example Actual phylogenetic inferences often use many taxa and a large number of characters (e.g., thousands or hundreds of thousands of nucleotide sites)
Inferring phylogenies using DNA sequences: real example Yuan and Olmstead, 2008. Mol. Phylogenet. Evol. 48: 23-33
Reproductive morphology: flower Hypericum sp.
Flower parts pedicel receptacle sepals petals
Flower parts (cont.) Pedicel stalk of a single flower (from Lartin: ped=foot); Receptacle - end of stem on which flower is borne; Sepals - outer (lower) whorl of parts; often greenish; -often function to protect in bud, but sometimes more colorful and showy than petals and attract pollinators; Calyx - collective term for sepals of one flower (from Greek: kalux to cover); Petals - second whorl of parts; often colorful and showy -often function to attract pollinators; Corolla - collective term for petals of one flower (Lartin = crown); Perianth collective term for calyx and petals; Tepals -perianth parts that are not differentiated into sepals and petals (e.g., Tulip) Ref.1 sepal tepals petal
Corolla Polypetalous - petals separate Gamopetalous/sympetalous - petals fused Actinomorphic/radially symmetric/regular - multiple planes of symmetry Zygomorphic/bilaterally symmetric/irregular - a single plane of symmetry
Flower parts (cont.) Note: in this flower, the pistil is compound, consisting of five fused carpels. stigma Pistil (5 fused carpels) style ovary anther filament Stamen
Flower parts (cont.) Stamens - pollen bearing part of the flower, consist of long filament (stalk) supporting the anther, where pollen is produced; - provide male function in reproduction; Androecium - collective term for male portion of flower (G. andro=male, oecium from oikos=house); Carpel - ovule producing structures, consists of swollen ovary at base, elongate style supporting the stigma at the tip, where pollen is deposited and germinates. Style is the structure via which pollen travels down to ovules. -provides female function in reproduction; 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 When fused together, one pistil may consist of many carpels - compound pistil (Note: see Figs. 4.19 and 4.20 in your textbook for more illustrations). Gynoecium - collective term for female portion of flower (may be one or many pistils)
Carpel vs. Pistil
Ovary position
Ovary position Superior ovary: ovary arising above the point of insertions of the other flower parts (i.e., perianth parts and stamens); The flowers thus hypogynous, With perianth parts and stamens arising from below the ovary. Inferior ovary: ovary that is beneath the point of insertions of the other floral parts; The flowers epigynous, with perianth and stamens apparently borne upon the ovary. Hypanthium: Flat, cuplike, or tubular structure on which the sepals, petals, and stamens are borne; usually formed from the fused bases of the perianth parts and stamens or from a modified receptacle; Half inferior ovary: A floral condition where the floral parts attach midway on the ovary such that it is partly superior and partly inferior. In this case, the flowers are perigynous, with perianth parts and stamens borne on an hypanthium that surrounds, but is not fused to, the ovary
Ovary position quiz hypanthium Superior; hypogynous Textbook DVD KRR&DLN Superior; hypogynous Inferior; perigynous Textbook DVD KRR&DLN Textbook DVD KRR&DLN Inferior; epigynous Textbook DVD KRR&DLN Inferior; epigynous Textbook DVD KRR&DLN hypanthium Superior; perigynous
Flower parts (cont.) Textbook DVD KRR&DLN Ovule - the egg-producing structure; Placenta (plural placentae) - part of the ovary to which the ovules attach to; Placentation - Arrangement of ovules within the ovary. placenta ovule
Placentation septum pl. septa locule basal free-central free-central Parietal placentation: ovules attached to the wall of the ovary. Axile placentation: ovules attached to the central axis of the ovary with two or more locules. Free-central placentation: ovules attached to a freestanding column or central axis in the middle of a unilocular ovary. Basal placentation: ovules attached at the base of the ovary.
Placentation quiz Textbook DVD KRR&DLN Textbook DVD KRR&DLN Parietal; one locule Axile; three locules Textbook DVD KRR&DLN Basal; one locule Textbook DVD KRR&DLN Free central; one locule
Placentation quiz (cont.) Textbook DVD KRR&DLN Ref2 Axile; three locule How about cucummbers? Free central; one locule Ref3 Free central; one locule
More on flower parts 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; fusion of LIKE parts. (e.g., gamopetalous corolla: petals fused together) adnate - parts on one whorl fused to parts in another whorl; fusion of UNLIKE parts from different whorls. (e.g., epipetalous stamens: stamens adnate to petals.) Textbook DVD KRR&DLN Connate: gamopetalous corolla Adnate: epipetalous stamens
More on flowers complete - all four whorls present incomplete - one or more whorls missing perfect - both reproductive whorls present; bisexual imperfect - one reproductive whorl missing; unisexual monoecious - plants with imperfect (unisexual) flowers, in which both sexes are on the same plant dioecious - plants with imperfect (unisexual) flower, in which each sex is on a separate plant Polygamous - plants with both perfect (bisexual) and imperfect (unisexual) flowers on the same plant Textbook DVD KRR&DLN Textbook DVD KRR&DLN Imperfect and imcomplete Imperfect and imcomplete
Inflorescence Inflorescence: positions and arrangements of flowers on a plant.
Inflorescence (cont.)
Inflorescence (cont.)
Inflorescence (cont.)
Inflorescence quiz (cont.) Ref.1 Textbook DVD KRR&DLN Ref.4 Solitary: a single flower formed in the axil of a leaf (solitary axillary flower) or at the terminus of a vegetative axis (solitary terminal flower). Raceme: simple, indeterminate inflorescence with a single axis bearing pedicellate flowers. Panicle: Indeterminate inflorescence with two or more orders of branching, each axis bearing flowers or higher order axes
Inflorescence quiz (cont.) Textbook DVD KRR&DLN Textbook DVD KRR&DLN Textbook DVD KRR&DLN Umbel Spike Spadix Spike: Simple, indeterminate inflorescence with a single axis bearing sessile flowers. Umbel: Determinate or indeterminate inflorescence in which all flowers have pedicels of equal or unequal length that arise from a single region at the apex of the inflorescence axis. Spadix: Spike with a thickened, fleshy axis, as characteristic of members of the Araceae.
Inflorescence quiz (cont.) Textbook DVD KRR&DLN Spikelet Catkin Textbook DVD KMN Textbook DVD KRR&DLN Head or Capitulum Spikelet: small spike, as in the basic inflorescence units of members of Poaceae and Cyperaceae. Catkin: inflorescence consisting of a dense, elongated mass of inconspicuous, usually wind-pollinated flowers; also called an ament. Head or Capitulum: compact determinate or indeterminate inflorescence with a very short, often disklike axis and usually sessile flowers.
Inflorescence quiz (cont.) Textbook DVD WSJ Textbook DVD WSJ Corymb Cyme Cyme Textbook DVD WSJ Cyme: determinate, compound inflorescence composed of repeating units of a pedicel bearing a terminal flower and below it, one or two bracteoles; each bracteole is associated with an axillary flower, and further bracteoles, and so on. Corymb: raceme with the pedicels of the lowermost flowers elongated, bringing all flowers to more or less the same level, i.e., a flat-topped raceme.
Fruit Fruit - mature ovary; once the eggs within the ovules have been fertilized and the ovary starts to expand, it is usually called a fruit and contains seeds; What "vegetables" are actually fruits (mature reproductive part of plant)? [e.g., tomato, cucumber, pumpkin, zucchini, peas, beans, corn] You will see many different types of fruits in lab.
Vegetative morphology Seed Starting point of plant after meiosis and fertilization. The seed is a young plant in which development is arrested and the plant is dormant. From the seed emerges a stem, or plumule, and a primary root, or radicle. Plumule (seed shoot) emerges 2 nd, radicle (seed root) emerges 1 st to take up H2O for germination and growth. Monocotyledon vs. dicotyledon Cotyledon = leaf developed at 1 st node of embryo (seed leaf) Example: peanuts with 2 cotyledons ( dicot ) Seed coat is the brown thin skin around peanut Radicle first to emerge Plumule with 2 first true leaves Food is stored in the seed in the cotyledons.
Vegetative morphology (cont.) Roots = cylindrical plant axes that lack external nodes & buds; absorb H2O and minerals, store nutrients, and anchor; mostly underground, sometimes aboveground. If the primary root persists (from radicle), it is called a true root and may take the following forms: taproot - single main root (descends vertically) with small lateral roots (e.g., carrot, reddish) fibrous roots - many divided roots of +/- equal size & thickness; thin root arising from another root fibrous root system. adventitious roots = roots that originate from stem (or leaf tissue) rather than from interior of another root (e.g., All roots on monocots are adventitious roots; corn and other grasses).
Vegetative morphology (cont.) Stems = cylindrical leaf-bearing main axes of a plant externally divided into nodes and internodes; with external buds that develop into branches and/or flowers * primary place of growth * can be aerial or subterranean At the tip of the growing shoot is a terminal bud or apical bud. Bud = external meristem that gives rise to leafy stems or flowers. Example: Pseudotsuga menziesii A bud has bud scales surrounding it to protect the developing parts inside. Inside a bud is a preformed shoot with growing tissue. The apical meristem is responsible for new terminal growth. = undifferentiated, actively dividing tissue at the growing tips of shoots Below the terminal bud regions of the stem may be identified as follows: node - point of attachment of a leaf on stem or branch lateral bud (axillary 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 successive nodes.
Vegetative morphology (cont.) Modified stems (true stems with apical buds and lateral buds): rhizome - underground laterally growing stem; horizontal stem that spreads and perennates a plant leaves often reduced to scales; with adventitious roots tuber - modified rhizome; solid, enlarged, horizontal, shortened stem, usually below ground for food storage with nodes & buds Example: potato (eyes = lateral buds) bulb - underground, thickened, short vertical stem axis with large, fleshy storage leaves attached Example: onion corm - underground, solid, erect, enlarged stem with leaves absent or dry and scalelike (2-several pairs) stolon runner or rhizome above the soil; horizontal stem at or just above the ground surface that gives rise to a new plant at its tip or from axillary branches Example: strawberry plants (Fragaria)
Vegetative morphology (cont.) Leaves = lateral appendages on stem that serve as the primary photosynthetic surface of the plant, attached at nodes with buds arising in axils. 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 = pair of appendages at the base of the leaf, occasionally fused, or woody and hard; sometimes falling off soon after leaf develops. In some groups of plants, stipules absent, in other groups, generally always present and diagnostic. Original function may have been for protection of emerging leaf, but now in many plants, vestigial and small, with no obvious function. Can become hardened with lignin to form a spine (protection against predation by herbivores), modified into a tendril for climbing, etc.
Vegetative morphology (cont.) Leaf structure: blade (lamina) - the broad part of the leaf, thin and flattened; principal photosynthetic surface petiole - the slender part of the leaf that attaches the blade to the stem; stalk of a leaf, sometimes absent margin (edge) - the edge of the blade; may be smooth or variously shaped ribs (veins) - vascular bundles or veins in the leaf; the central one is the midrib Venation (arrangement of veins) - net veined - a branching, divergent and often reticulate pattern may be palmate or pinnate Example: Magnolia pinnate = pattern of a single, large midvein and secondary veins diverging from it; veins arranged like pinnae on a feather. palmate = pattern of veins with 3+ primary veins diverging from a common point at the base of a leaf blade; with secondary veins diverging from each primary vein; veins arranged like fingers radiating from the palm of your hand. - parallel veined - primary veins all parallel
Vegetative morphology (cont.) Leaf Type: simple - undivided blade (single blade) compound - blade divided into leaflets, each resembling a leaf. 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. pinnately compound compound leaf with leaflets attached like pinnae /vanes on a feather to an elongated rachis. palmately compound compound leaf with leaflets radiating from a common point of attachment like fingers radiating from the palm of your hand; no rachis. Leaves may be pinnately or palmately compound, however when there are three leaflet it may be impossible to tell which. In that case the leaves are called ternately compound.
Vegetative morphology (cont.) Leaf Arrangement (attachment of leaves to stem) Alternate one leaf attached at each node Opposite two leaves attached per node on opposite sides of stem Whorled more than two leaves per node, symmetrically distributed around the stem at the same node. Basal In plants that form rosettes, all leaves arise directly from the crown of the plant. No leafy stem.
Image Source Ref.1 http://www.freefoto.com/images/12/61/12_61_52---tulip_web.jpg Ref.2 http://images.jupiterimages.com/common/detail/80/66/23466680.jpg Ref.3 http://home.comcast.net/~suzyq9/marioqbellopencompare.jpg Ref.4 http://www.duke.edu/~cwcook/trees/yufi4897.jpg