PlantKingdom213S - Introduction to the Plant Kingdom - 1...

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Introduction to the Plant Kingdom - 1 The Plant Kingdom comprises a large and varied group of organisms that have the following characteristics in common. Plants are: Eukaryotic Photosynthetic, with primary chloroplasts containing chlorophyll a and b Multicellular with tissue development Sexually reproducing with an "alternation of generations" life cycle Most plants are terrestrial. Plants evolved from green algae ancestors (Charophyceae) that successfully inhabited land. When, when included with the plant kingdom, the Charophytes and Plants form the Streptophyes. As we have discussed, plants must obtain their nutrients from both air and soil, and much of their structure relates to the need to maximize obtaining nutrients and water, minimizing water loss and protecting the plant from damage while surviving on land. Plant Kingdom and Alliances To this end plants evolved (details later) : Protective waxy surface layers to minimize desiccation – cuticle Gas exchange structures to circumvent the cuticle – stomata Growth from apical meristems Increase in dimension with conducting and support tissues – the vascular tissue
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Introduction to the Plant Kingdom - 2 Increase in photosynthetic surface area – leaves Plant pigments to screen harmful UV light Mutualisms with mycorrhizae fungi to increase nutrient uptake from soil Thickened spore walls, containing sporopollenin, which resists desiccation and decay Protection for developing embryos within parent tissue, hence plants are sometimes called Embryophytes And with seed plants: o Reproductive strategies that work without water transport of gametes o Dispersal via seeds rather than single-celled spores Who are the Land Plants? In Biology 213, we will focus on the land plants. The general classification of plants uses the following features to divide land plants into a number of phyla: Presence or absence of vascular tissue Dispersal by spores or by seeds Seed plants are distinguished further by the protection of the seed.
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Introduction to the Plant Kingdom - 3 Classification of Land Plants In addition to the extant plant phyla, both non-vascular and vascular, we have several phyla comprised of extinct vascular plants. We use the fossil record of the extinct vascular plants to trace our plant ancestors. Moreover, long-extinct precursors of today’s vascular plants are the source of most of the world’s coal deposits. Vascular Plant Evolutionary Tree
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Introduction to the Plant Kingdom - 4 The Non-Vascular Plants The non-vascular plants include the mosses, hornworts and liverworts. Because they lack vascular tissue they are small in vertical stature, and typically grow in clumps or masses. Most lack a cuticle and many are capable of withstanding long periods of desiccation. They attach to their substrate with “rhizoids”, but absorb water and minerals through all surface cells. Some have air pores for diffusion of gases.
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PlantKingdom213S - Introduction to the Plant Kingdom - 1...

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