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| Plants | ||||
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Five-finger fern | ||||
| Scientific classification | ||||
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Green algae land plants (embryophytes) non-vascular embryophytes Hepatophyta - liverworts Anthocerophyta - hornworts Bryophyta - mosses vascular plants (tracheophytes) seedless vascular plants Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta – "true" ferns Psilotophyta – whisk ferns Ophioglossophyta - adderstongue ferns seed plants (spermatophytes) Pinophyta - conifers Cycadophyta - cycads GinkgophytaThe Ginkgo Ginkgo biloba , sometimes also known as the Maidenhair tree is a unique tree with no living relatives, being classified within its own division, the Ginkgophyta comprising the single class Ginkgoopsida order Ginkgoales family Ginkgoaceae genus - ginkgo Gnetophyta - gnetae MagnoliophytaMagnoliopsida Dicots Liliopsida Monocots The flowering plants (also angiosperms or Magnoliophyta are one of the major groups of modern plants, comprising those that produce seeds in specialized reproductive organs called flowers, where the ovulary or carp - flowering plants |
Plants are a major group of living things (about 300,000 species), including familiar organisms such as trees, flowers, herbs, and ferns. AristotleAristotle ( Greek Αριστοτλης Aristotelēs) ( 384 BCE March 7, 322 BCE) was a Greek scientist and philosopher. Along with Plato, he is often considered to be one of the two most influential philo divided all living things between plants, which generally do not move or have sensory organs, and animals. In LinnaeusCarolus Linnaeus (later, Carl von Linn ( May 23, 1707 January 10, 1778) was a Swedish scientist who laid the foundations for the modern scheme of taxonomy. He is also considered one of the fathers of modern ecology (see History of ecology). Biography Carl' system, these became the Kingdoms Vegetabilia (later Plantae) and Animalia. Since then, it has become clear that the Plantae as originally defined included several unrelated groups, and the fungiChytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus are a large group of organisms ranked as a kingdom within the Domain Eukaryota. Included are the conspicuous mushrooms, but also many microscopic forms such as molds and yeast and several groups of algaThe algae (singular is alga comprise several different groups of living things that produce energy through photosynthesis. They are generally regarded as simple plants, and some are related to the higher plants. Others represent independent lines of evolue were removed to new kingdoms. However, these are still often considered plants in many contexts. Indeed, any attempt to match "plant" with a single taxon is doomed to fail, because plant is a vaguely defined concept unrelated to the presumed phylogenic concepts on which modern taxonomy is based.
Most familiar are the multicellular land plants, called embryophytes. They include the vascular plants, plants with full systems of leaves, stems, and roots. They also include a few of their close relatives, often called bryophytes, of which mosses are the most common.
All of these plants have eukaryotic cells with cell walls composed of cellulose, and obtain their energy through photosynthesis, using light and carbon dioxide to synthesize food. They are distinguished from green algae, from which they evolved, by having specialized reproductive organs protected by non-reproductive tissues.
Bryophytes first appeared during the early Palaeozoic. They can only survive in moist environments, and remain small throughout their life-cycle. This involves an alternation between two generations: a haploid stage, called the gametophyte, and a diploid stage, called the sporophyte. The sporophyte is short-lived and remains dependent on its parent.
Vascular plants first appeared during the Silurian period, and by the Devonian had diversified and spread into many different land environments. They have a number of adaptations that allowed them to overcome the limitations of the bryophytes. These include a cuticle resistant to desication, and vascular tissues which transport water throughout the organism. In many the sporophyte acts as a separate individual, while the gametophyte remains small.
Phylogeny of the modern Spermatophyta (seed plants) and some allied vascular plant groups. Note that the spore-bearing vascular plants are paraphyletic with respect to the seed plants, with ferns (Pteridophyta) more closely allied to seed plants than they are to clubmosses (Lycopodiophyta) The first primitive seed plants, Pteridosperms (seed ferns) and Cordaites, both groups now extinct, appeared in the late Devonian and diversified through the Carboniferous, with further evolution through the Permian and Triassic periods. In these the gametophyte stage is completely reduced, and the sporophyte begins life inside an enclosure called a seed, which develops while on the parent plant, and with fertilisation by means of pollen grains. Whereas other vascular plants, such as ferns, reproduce by means of spores and so need moisture to develop, some seed plants can survive and reproduce in extremely arid conditions.
Early seed plants are referred to as gymnosperms (naked seeds), as the seed embryo is not enclosed in a protective structure at pollination, with the pollen landing directly on the embryo. Four surviving groups remain widespread now, particularly the conifers, which are dominant trees in several biomes. The angiosperms, comprising the flowering plants, were the last major group of plants to appear, emerging from within the gymnosperms during the Jurassic and diversifying rapidly during the Cretaceous. These differ in that the seed embryo is enclosed, so the pollen has to grow a tube to penetrate the protective seed coat; they are the predominant group of flora in most biomes today.
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