Flowering Plants - Angiosperms PDF

Flowering Plants - Angiosperms Flowering Plants - Angiosperms Largest group of Land Plants! Most important economically! Apomorphies: 1. Flowers 2. Carpels 3. Fruits 4. Double fertilization with triploid endosperm 5. Specialized conductive cells Why have Angiosperms been so...

Flowering Plants - Angiosperms Flowering Plants - Angiosperms Largest group of Land Plants! Most important economically! Apomorphies: 1. Flowers 2. Carpels 3. Fruits 4. Double fertilization with triploid endosperm 5. Specialized conductive cells Why have Angiosperms been so successful?  1) Flowers What is a flower? = Shoot system bearing modified leaves: } Perianth Calyx (sepals) - green, protective modified Corolla (petals) - colored, attractant leaves Stamens - male Carpels - female  pistil Fig. 30.7 Flower parts:  Flower pollination (transfer of pollen to ovule): Animal pollination Ancestral for Angiosperms Much more efficient means of transporting pollen All Gymnosperms are wind pollinated (Some Angiosperms secondarily wind pollinated)  Strategy of animal pollination: Attractant Visual: large or brightly colored perianth Olfactory (smell): sweet or rotten (fetid) odor Reward Usually nectar or pollen (Rarely waxes, oils)  Pollination Mechanisms Insects Bees Butterflies/Moths Flies Birds Bats Water Wind Bee-pollinated Moth-pollinated Fly-pollinated Bird-pollinated Bat-pollinated Wind pollination in grasses Phyllospadix torreyi Water-pollinated Surf-Grass  2) Carpels Carpel = conduplicate megasporophyll Conduplicate = folded Megasporophyll = “female leaf, bearing seeds” Carpel totally encloses ovules/seeds  Carpels can fuse together Gynoecium = all female parts Pistil = ovary + style + stigma Pistil can be one carpel or many orange: 8 fused carpels carpel  Function of Carpel 1. Protects young seeds 2. Site of pollen germination - Can induce self-incompatibility reactions 3. Fruits  Self-incompatibility - Pollen will not germinate on genetically similar individuals - Promotes outcrossing  3) Fruits Fruit = mature ovary (plus accessory parts) Function: seed dispersal Fruit types: dry - dispersed mechanically, by wind, water, etc. fleshy - dispersed by animals 4) Double fertilization in Angiosperms  Double fertilization in Angiosperms Pollen produces 2 sperm cells:  Double fertilization in Angiosperms Pollen produces 2 sperm cells: sperm (n) + egg (n) ----> zygote (2n) sperm (n) + 2 polar nuclei (n) ----> endosperm (3n) Triploid endosperm is nutritive tissue in seeds of Angiosperms. Extra set of genes may help in: 1) rapid development 2) increase genetic variation Gymnosperms: - Fertilization occurs long after pollination - Seeds mature slowly (1-2 years) Angiosperms: - Fertilization occurs soon after pollination - Seeds produced rapidly - Selective advantage (e.g., annual herbs)  5) Specialized conductive cells Most Angiosperms have vessels Specialized in having perforation plates vessel perforation plate All Angiosperms have sieve tube members -with sieve plates: bigger pores in end walls big callose-lined pores  Angiosperms Vessels and sieve tube members more efficient in water / sugar conduction Angiosperm Classification  seed endosperm coat Old classification: 2 cotyledons epicoty Dicots - 2 cotyledons (seed leaves) embry o { l hypocotyl radicl e NON-MONOCOT Monocots 1 cotyledon - 1 cotyledon coleoptile epicoty 1 cotyledon l epicotyl hypocotyl embry radicle o radicle coleorhiza MONOCOTS Monocots monophyletic Monocot apomorphies  Monocot apomorphies 1 cotyledon coleoptile 1 cotyledon epicotyl epicotyl hypocotyl embryo radicle radicle coleorhiza MONOCOTS 1 cotyledon parallel venation stem an atactostele -many scattered vascular bundles (wood lost!)  Monocots include: Palms Orchids Irises Grasses, etc. “Dicots” paraphyletic!  Eudicots monophyletic!  Eudicot apomorphy: A A A Pollen tricolpate - 3 apertures All other Angiosperms: aperture Pollen has 1 aperture  Eudicots include most angiosperms: Roses Legumes Daisies Oaks, etc.