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The evolution of plants has resulted in a wide range of complexity, from the earliest algal mats, through multicellular marine and freshwater green algae, terrestrial bryophytes, lycopods and ferns, to the complex gymnosperms and angiosperms of today.
Plants are thought to have evolved from a class of freshwater green algae called the charophytes. Two particular groups of charophyte, the Coleochaetales and the Charales, resemble the earliest land plants (bryophytes) in a variety of ways, including the structure of their chloroplasts and sperm cells, and the way their cells divide during mitosis .
Read more: http://www.biologyreference.com/Ep-Fl/Evolution-of-Plants.html#ixzz5L2gpgx7BThe scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants, bryophytes, ferns and fern allies. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering and 18,000 bryophytes (see table below). Green plants, sometimes called Viridiplantae, obtain most of their energy from sunlight via a process called photosynthesis.
Plant Tissue Systems
Plant Tissue Systems
- Plant Tissue Cells - parenchyma cells, collenchyma cells, sclerenchyma cells.
- Dermal Tissue - epidermis, trichomes.
- Vascular Tissue - xylem, tracheids, vessel elements, phloem, sieve tube elements, pressure-flow model.
- Ground Tissue - parenchyma, collenchyma, sclerenchyma.
- Meristematic Tissue - plant growth by mitosis.
- Leaves - blades, petiole, mesophyll, gaurd cells, compound leaf, leaflet.
- Stems - node, internode, bud, vascular cambium, primary growth, secondar growth, tree rings, heartwood, sapwood, bark.
- Roots - fibrous roots, taproot, root hairs, root cap, meristem, cortex, endodermis, vascular cylinder.
- Cohesion-tension Theory - cohesion, adhesion, transpiration, capillary action, absorption.
Angiosperm
Angiosperm
- Plant Classification - vascular tissues, seeds, flowers.
- Sporophyte - spore producing plant, diploid.
- Gametophyte - gamate producing plant, haploid.
- Flowering Plants - Monocotyledonae, Dicotyledonae.
- Monocots - flower parts in mliples of 3, single cotyledon, parallel viens, scattered vascular bundles, fibrous roots.
- Dicots - flower parts in multiple of 4 and 5, paired cotyledons, branched veins, arranged vascular bundles, taproot.
- Annuals - complete life cycle within one year.
- Biennials - complete life cycle within two years.
- Perennials - complete life cycle longer than two years.
Gymnosperm
Gymnosperm
- Gymnosperm - Gnetophytes, Cycads, Ginkgoes, Conifers.
- Pollination - wind, pollination drop.
- Pollen Cones - male gametophytes, pollen grains.
- Seed Cones - female gametophytes, ovules.
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