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THE PLANTS. Eukaryotic Domains. Supergroup Plantae. Original photosynthetic symbionts Includes the red algae and the green plants All with somewhat simple walls. Green Plants. Chlorophylls a and b Walls of cellulose Store starch. Green Plants.
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SupergroupPlantae • Original photosynthetic symbionts • Includes the red algae and the green plants • All with somewhat simple walls
Green Plants • Chlorophylls a and b • Walls of cellulose • Store starch
Green Plants FIGURE 1. MAJOR CLADES OF THE GREEN PLANTS. This system reflects all of these changes in the taxonomy of the Viridiplantae with two subkingdoms: Chlorobionta and Streptobionta. See the Tree of Life Project and Palmer et al. (2004) for the consensus view of the molecular/ ultrastructural relationships between the higher taxa of the green plants. CH = Chlorobiont Clade ST = Streptobiont Clade EM = Embryophytes VP = Vascular Plants SP = Seed Plants
Tracheophytes • Plants have vascular tissue • Xylem • Phloem • Usually with stems, roots, and leaves
Flowering plants • Contain flowers • Fruit is derived from the ovulary of the flower
Major Types of Flowering Plants • Primitive Dicots • Magnolias and their relatives • Monocots • Derived Dicots
Primitive Dicots Amborella, sister to all other living flowering plants Water Lilies
Magnolias and their Relatives Magnolia flower Avacado
Monocots Orchid Wheat
Flowers –large and small Wolffia in flower, floating plant Rafflesia, largest flower, related to euphorbias and parasitic on vines of SE Asia Amorphophallustitanum, largest unbranched inflorescence, an aroid.
Major Events in Plant Evolution • Appearance of land plants initially limited to mosses and relatives during Ordovician Period (~470-440 mya) based on fossil spores. • Plants restricted to lowlands and wet areas of temperate to tropical latitudes. Mosses growing in a Scotland bog, their success related to symbioses with fungi. Likely, this was true at the time of the earliest emergence. (David Beerling, University of Sheffield)
Life on Land Advantages Disadvantages Exposure to UV light Need for water storage and uptake Need for photosynthate used for support • Unfiltered light • Atmosphere larger reservoir of CO2 • Initially, fewer predators?
Major Events in Plant Evolution • Vascular tissue • Shift to dominance of spore-producing portion of life cycle Restoration of Cooksonia from Silurian Vascular tissue in stem of Rhynia, lower Devonian
Major Events in Plant Evolution Late Devonian Pennsylvanian
Major Events in Plant Evolution The Seed
Major Events in Plant Evolution These are from the lower Cretaceous, but flowering plant pollen has been found in strata 100 my earlier.
Wasp attempting to copulate with an orchid The Bee Orchid