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Information about Plant

Plants are multicellular eukaryotic                   Plants
organisms that generally do not have
sensory organs or voluntary motion           Scientific classification

and have, when complete, a root,       Domain:   Eukaryota
stem, and leaves, though consisting
sometimes only of a single leafy       Kingdom:  Plantae

expansion.                                           Divisions
                                       Simple nonvascular plants
                                           Green algae
Plant Classification                   Complex nonvascular plants
                                           Bryophyta - mosses
Plants find their origins among a          Hepatophyta - liverworts
group called the green algae, which        Anthocerophyta - hornworts
are paraphyletic to the remaining      Vascular plants
forms, and are variously included      Seedless
here or among the Protista. Green          Psilophyta - whisk ferns
algae have chloroplasts containing         Lycophyta - club mosses
chlorophylls a and b, bound by double      Sphenophyta - horsetails
membranes, and come in a variety of        Ophioglossophyta
forms: flagellate, colonial,               Pterophyta - ferns
filamentous, and even primitively      Seeded
multicellular. Many are primarily          Pinophyta - conifers
haploid, but others exhibit                Cycadophyta - cycads
alternation of generations between         Ginkgophyta - ginkgo
haploid and diploid forms, called the      Gnetophyta - Gnetae
gametophyte and sporophyte                 Magnoliophyta - flowering plants

Some time during the Palaeozoic plants began to appear on land. In these new
forms, the gametophyte and sporophyte become very different in shape and
function, the sporophyte remaining small and dependent on its parent for its
whole brief life. Groups at this level of organization, collectively called
bryophytes, include:

   * Division Bryophyta (mosses)
   * Division Anthocerotophyta (hornworts)
   * Division Hepaticophyta (liverworts)

All of these forms are small and confined to moist environments, relying on
water to disperse spores. In the Silurian, new embryophytes appeared with
adaptations enabling them to overcome these constraints, which underwent a
massive adaptive radiation in the Devonian period, taking over the land.
These groups typically have a cuticle resistant to desiccation, and vascular
tissue, which transports water throughout the organism, and are called
vascular plants as a result. In many of these the sporophyte acts as a
separate individual, with the gametophyte remaining very small. Groups at
this level of organization include:

   * Division Lycophyta (club mosses)
   * Division Sphenophyta (horsetails)
   * Division Psilophyta (whisk ferns)
   * Division Ophioglossophyta (adders-tongues and grape-ferns)
   * Division Pterophyta (ferns)

The vascular plants also include as a subgroup the spermatophytes, or seed
plants, which diversified towards the end of the Palaeozoic. In these forms
it is the gametophyte that is completely reduced, and the young sporophyte
begins life inside an enclosure called a seed, which develops on its parent.
Spermatophytes include:

   * Division Cycadophyta (Cycads)
   * Division Ginkgophyta (Ginkgo)
   * Division Pinophyta (Conifers, Coniferophyta)
   * Division Gnetophyta (Gnetae)
   * Division Magnoliophyta (Flowering plants, Anthophyta)

These divisions are grouped into gymnosperms (naked seeds; first four), and
the flowering plants or angiosperms. The latter are the last major group of
plants to have appeared, arising during the Jurassic and quickly becoming
predominant in most biomes.

Plant Life Cycles and Forms

Plants may be organized according to their growth pattern:

   * Annual: live for one growing season
   * Biennial: live for two growing seasons
   * Perennial: live for many growing seasons
        o Herbaceous (nonwoody): soft stems
        o Woody: hard stems which enable tall growth
             + Trees: one or several trunks, with branching occuring well
               above ground
             + Shrubs: no trunk, so branching occurs near ground surface

Plants may also be organized according to how they are used. Food plants
include fruits, vegetables, herbs, and spices.

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