KINGDOM PLANTAE

Plants are adapted to living on land. In general, they tend to have features that allow them to live and reproduce on land.

Multi celllular, primilly terrestrial eukaryotes with well-developed tissues; autotrophic by photosynthesis; alternation of generations life cycle. Like green algae, plants contain chlorophylls a and b and carotenoids; store starch in chloroplast; cell wall contains cellulose.

NONVASCULAR PLANTS

Division Hepatophyta: liverwort, example: Marchantia polymorpa

Division Bryophyta: mosses, example: Spaghnum sp

Division Anthocerophyta: hornwort, example: Antherocephala sp.

SEEDLESS VASCULAR PLANTS

Division Psilotophyta:whisk ferns, example: Psilotum nudum

Division Lycopodophyta: club mosses, Lycopodium clavatum, L. ceernum

Division Equisetophyta: horsetails, example: Equisetum debile

Division Pteridophyta: ferns, example: Marsilea crenata, Azola pinnata

SEED VASCULAR PLANTS

            Gymnosperms

            Division Pinophyta: conifers, example: Pinus merkusii

            Division Cycadophyta: cycads, example: Cycas rumphii

            Division Gynkgophyta: maidenhair tree, example: Gynkgo biloba

            Division Gnetophyta: gnetophytes, example: Gnetum gnemon

            Angiosperms

            Division Magnoliophyta: Flowering plants

                        Class Magnoliopsida: dicots, example: Mangifera indica

                        Class Liliopsida: monocots, example: Oryza sativa

1. NON VASCULAR PLANTS ARE DIVERSE

            The nonvascular plants, which include the liverworts and mosses, are non vascular plants and therefore lack true roots, stems and leaves. In the moss life cycle, the gametophyte is dominant. Antheridia produce swimming sperm that need external water to reach the eggs in the archegonia. Following fertilization, the dependent sporophyte consists of a foot, a stalk., and a capsule within which wind blown spores are produced by meiosis. Each spore germinates to produce a gamethophyte.

2. VASCULAR PLANTS INCLUDE SEEDLEES AND SEED PLANTS

            Vascular plants arose during the Silurian period of the Paleozoic era. The extinct rhyniophytes may be ancestral vascular plants. These plants had photosynthetic stems (no leaves or roots) with sporangioa at their tips. Most likely, the life cycle was similar to today’s ferns. The sporophyte, which is diploid and has vascular tissue, is the dominant generation in ferns. This separates gametophyte produces heterospores which develop into heterogametes. Every aspect of the life cycle is adapted to a dry environment.

3. FERNS AND ALLIES ARE SEEDLESS VASCULAR PLANTS

            The seedlees vascular plants include whisk fern, club mosses, horsetails, and ferns. Lycopods, horsetails and ferns were also trees during the Carboniferous period, although lycopods and horsetails are limited in diversity and rather small today. Seedless vascular plants  have a life cycle like that of the ferns.

            In ferns, the separate and water-dependent gametophyte (the heart-shaped prothallus) produces flagellated sperm in antheridia and egg in archegonia. Following fertilization, the zygote develops into the sporophyte, which has large fronds. On the underside of the fronds are sori(singular: sorus), each containing several sporangia. Here meiosis produces windblown spores, each of which develop into a prothallus.

            The Mesozoic era saw many geological changes as Pangaea formed and then broke apart. A mass extinction occured that paved the way for the diversification of the seed plants. Thoose seed plants that are trees have especially weel-developed roots and steems due to secondary growth of vascular tissue. Seed plants produce heterospores, microgametophytes, ang megagametophytes. The poolen grain replaces external flagellateds sperm, and the megagametophyte is retained within the ovule that develops into the seed.

4. GYMNOSPERMS HAVE NAKED SEEDS

            There are four divisions of gymnosperms (seed plants that bear naked seeda); the familiar conifers and the little-known cycads, ginkgo, and gnetophytes. In conifers, pollen (male) and seed (female) cones are produced by the sporophyte plant. On the under side of a pollen cone scale, there are two microsporangia that produce microspores; each becomes a micrgametopyte, or pollen grain.On the upper surface of a seed cone scale, there are two ovules, where meiosis produces one megasopre that develops into the megagametophyte. After windblown pollination, the pollen grain develops a tube through which sperm reach   the egg. After fertilization, the ovule matures to be a seed.

5. ANGIOSPERMS HAVE COVERED SEEDS

            Angiosperms (seed plants that bear seeds protected by a fruits) are more diverse than the other types of plants. Their success may be assosiated with climatic changes in the Cenozoic era.

            In a flower, the microsporangia develop within the anther portion of a stamen, and the megasporangia develop within ovules located in the ovary of the pistil. Pollination brings the mature microgamaetophyte (pollen grain) to the pistil, and the pollen tube brings the sperm to the ovule within the ovary. Angiosperms exhibit double fertilization; one sperm fertilizes the egg, and the other unites with the polar nuclei to form the endosperm, which is food for the embryo. The ovule develops into the seed, and the ovary becomes the fruit.

            Angiosperms have complex vascular tissue and are found in various habitats. Their reproductive organs are found in flowers. Animal pollination increases the chance of appropriate fertilization, and fruit production often assists the dispersal of seeds.