Kingdom: Plants Domain Eukarya Domain Domain Domain Eubacteria Archaea Eukarya 2007-2008 Common ancestor Evolution of Land Plants 500 mya land plants evolved special adaptations for life on dry land protection from drying = desiccation waxy cuticle gas exchange (through cuticle) stomates water & nutrient conducting systems from roots/soil to leaves xylem & phloem protection for embryo seeds Plant Diversity Bryophytes non-vascular land plants mosses Pteridophytes seedless vascular plants ferns colonization of land Ancestral Protist Gymnosperm pollen & naked seeds conifers monocot 1 seed leaf pollen & seeds dicot 2 seed leaves Angiosperm flowers & fruit flowering plants flowers vascular system = water conduction Tracheophytes xylem cells = tracheids Animal vs. Plant life cycle mitosis zygote 2n fertilization Animal multicellular individual 2n unicellular gametes no multicellular meiosis gametes Plant multicellular sporophyte mitosis 2n zygote 2n fertilization meiosis spores mitosis mitosis multicellular gametophyte alternation of generations Bryophytes: 1 st land plants Bryophytes: mosses & liverworts vascular system? No! non-vascular no water transport system no true roots dominant stage? gametophyte stage Where must reduced, dependent sporophyte mosses live? fuzzy moss plant you are familiar with is reproduction? swimming sperm flagellated spores sprout to form gametophyte Bryophytes: mosses & liverworts 1
Peat Bog Peat Moss Pteridophytes: 1 st vascular plants Pteridophytes: ferns vascular system? Yes! vascular water transport system xylem, phloem, roots, leaves dominant stage? sporophyte stage Where must ferns live? fragile, independent gametophyte (prothallus) reproduction? swimming sperm flagellated spores sprout to form gametophyte Pteridophytes: Ferns Selaginella Psilotum Alternation of generations Fern gametophyte () homospory: male & female gamete production on same plant archegonia antheridia Horsetails Ferns Alternation of generations Early Pteridophytes: Tree Ferns produces male & female gametes archegonia Fossil fuels I get it! antheridia Carboniferous forest 290-350 mya Forests of seedless plants decayed into deposits of coal & oil 2
Pteridophytes: Tree ferns First seed plants: Gymnosperm fronds fiddleheads Gymnosperm: conifers vascular system? Yes! vascular xylem, phloem, roots, leaves dominant stage? sporophyte stage reduced (microscopic) gametophyte reduction of gametophyte protects delicate egg & Where can embryo in protective sporophyte conifers live? protected from drought & UV radiation heterospory: male vs. female gametophytes reproduction? seeds naked seeds (no fruit) pollen contain male gametophyte With fronds like these who needs enemies! Early Gymnosperm: ginkgo Gymnosperm: conifers Early Gymnosperm: cycads Cones & naked seeds 3
sporangium & pollen First flowering plants Angiosperm: flowering plants vascular system? dominant stage? Yes! vascular male sporophyte stage reduced (microscopic) gametophyte male (pollen) cones protects egg & embryo heterospory: male vs. female gametophytes female reproduction? flower sexual selection: attract pollinators seeds inside fruit sexual selection: attract seed spreaders female cones pollen pine embryo Angiosperm: flowering plants contain male gametophyte polar nuclei Angiosperm life cycle male gametophyte = pollen grain () pollen grains egg cell ovary sac sperm nuclei travel down pollen tube 3n endosperm female gametophyte = ovary sac () 2n zygote double fertilization 2n embryo new sporophyte in seed () Flower Modified shoot with 4 rings of modified leaves sepals Stamen petals stamens Identify the flower structures Stigma Style Ovary Anther Carpel Filament male carpel / pistil female sepals petals stamens Petal Ovule Sepal adaptations through mutations carpel 4
Flower variations Co-evolution: flowers & pollinators How a bee sees a flower insects see UV light = a bulls-eye to the nectar Angiosperm: fruiting plants Other fruits Seed & Plant embryo Seed offers protection for embryo stored nutrients for growth of embryo cotyledons = seed leaves, first leaves of new plant endosperm (3n) cotyledons embryo (2n) seed coat Monocots & dicots Angiosperm are divide into 2 classes dicots (eudicot) 2 cotyledons (seed leaves) leaves with network of veins woody plants, trees, shrubs, beans monocots 1 cotyledon leaves with parallel veins grasses, palms, lilies 5
Any Questions?? 6