Plant

Fossils of seed ferns such as Glossopteris are widely distributed throughout several continents of the southern hemisphere, a fact that gave support to Alfred Wegener's early ideas regarding Continental drift theory. Program or Programme may refer to:. Fossil forests of petrified wood have been found in all continents. British tabloid form of comic book, called "prog" in short. Such specimens may be cut and polished using lapidary equipment. Event programme. Petrified wood is often heavily silicified (the organic material replaced by silicon dioxide), and the impregnated tissue is often preserved in fine detail. Program (The Animatrix), a short film in The Animatrix series.

Petrified wood is common in some parts of the world, and is most frequently found in arid or desert areas were it is more readily exposed by erosion. 12-step program. Sequoia and its allies, magnolia, oak, and palms are often found. Program (management). The fossilized remains of conifer and angiosperm roots, stems and branches may be locally abundant in lake and inshore sedimentary rocks from the Mesozoic and Caenozoic eras. Webcast. In the Fossil Forest at Victoria Park in Glasgow, Scotland, the stumps of Lepidodendron trees are found in their original growth positions. Television program(me),.

The spoil heaps of coal mines are the best places to collect; coal itself is the remains of fossilised plants, though structural detail of the plant fossils is rarely visible in coal. Radio programming. The Coal Measures are a major source of Palaeozoic plant fossils, with many groups of plants in existence at this time. Computer program. This fern-like tree combined a woody trunk with the fronds of a fern, but produced no seeds. The Devonian period also saw the evolution of what many believe to be the first modern tree, Archaeopteris.

Early fossils of these ancient plants show the individual cells within the plant tissue. The remains of fossil plants are not as common as fossil animals, although plant fossils are locally abundant in many regions worldwide. Pollen, spores and algae (dinoflagellates and acritarchs) are used for dating sedimentary rock sequences. Fossil land plants are recorded in terrestrial, lacustrine, fluvial and nearshore marine sediments.

Plant fossils include roots, wood, leaves, seeds, fruit, pollen, spores, phytoliths, and amber (the fossilized resin produced by some plants). Some climbing species, such as kudzu, which do not need to produce thick supportive tissue, may grow up to 12.5 mm/h. Some mosses grow less than 0.001 mm/h, while most trees grow 0.025-0.250 mm/h. The growth rate of plants is extremely variable.

In temperate and boreal climates, they generally lose their leaves during the winter; many tropical plants lose their leaves during the dry season. Among the vascular plants, perennials include both evergreens that keep their leaves the entire year, and deciduous plants which lose their leaves for some part. Other plants may be organized according to their seasonal growth pattern:. Simple plants like algae may have short life spans as individuals, but their populations are commonly seasonal.

Plants rely on soil primarily for water (in quantitative terms), but also obtain nitrogen, phosphorus and other crucial nutrients. These sugars are then used as building blocks and form the main structural component of the plant. Through a process known as photosynthesis, plants use the energy in sunlight to convert carbon dioxide from the air into simple sugars. It is a common misconception that most of the solid material in a plant is taken from the soil, when in fact almost all of it is actually taken from the air.

A number of plants are used decoratively, including a variety of flowers. Some vascular plants, referred to as trees and shrubs, produce woody stems and are an important source of building material. Other plants that are eaten include fruits, vegetables, herbs, and spices. Much of human nutrition depends on cereals.

Animals and most other organisms are aerobic, relying on oxygen; those that do not are confined to relatively few, anaerobic environments. These processes also radically changed the composition of the Earth's atmosphere, which as a result contains a large proportion of oxygen. The photosynthesis and carbon fixation conducted by land plants and algae are the ultimate source of energy and organic material in nearly all habitats. Therefore, fungus has a kingdom of its own.

They are not related to any of the photosynthetic groups, but are close relatives of animals. Fruiting bodies, of which mushrooms are the most familiar, are actually only the reproductive structures of fungi. Most fungi are formed by microscopic tubes called hyphae, which may or may not be divided into cells but contain eukaryotic nuclei. Unlike embryophytes and algae, fungi are not photosynthetic, but are saprophytes: they obtain their food by breaking down and absorbing surrounding materials.

They are not in general close relatives of the green plants, acquiring chloroplasts separately from ingested or symbiotic green and red algae. In contrast, most other algae have chloroplasts with three or four membranes. The same is true of the red algae, and the two groups are generally believed to have a common origin. The chloroplasts of green plants are surrounded by two membranes, suggesting they originated directly from endosymbiotic cyanobacteria.

They undergo closed mitosis without centrioles, and typically have mitochondria with flat cristae. With a few exceptions among the green algae, all such forms have cell walls containing cellulose and chloroplasts containing chlorophylls a and b, and store food in the form of starch. The kingdom Plantae is now usually taken to mean this monophyletic group, as shown above. The embryophytes developed from green algae; the two are collectively referred to as the green plants or Viridiplantae.

Now they are considered neither, but protists. Many can move about, and some have even lost their ability to photosynthesize; when first discovered, these were considered as both plants and animals. These and other algal groups also include various single-celled creatures and forms that are simple collections of cells, without differentiated tissues. The most conspicuous are the seaweeds, multicellular algae that often closely resemble terrestrial plants, but as stated above are not plants, found among the green, red, and brown algae.

However, they are not classified within the kingdom plantae but in the kingdom protista instead. The algae comprise several different groups of organisms that produce energy through photosynthesis. 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. 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.

Four surviving groups remain widespread now, particularly the conifers, which are dominant trees in several biomes. 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. 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. 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.

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 most the sporophyte acts as a separate individual, while the gametophyte remains small. These include a cuticle resistant to desiccation, and vascular tissues which transport water throughout the organism. They have a number of adaptations that allowed them to overcome the limitations of the bryophytes.

Vascular plants first appeared during the Silurian period, and by the Devonian had diversified and spread into many different land environments. The sporophyte is short-lived and remains dependent on its parent gametophyte. This involves an alternation between two generations: a haploid stage, called the gametophyte, and a diploid stage, called the sporophyte. Most species of bryophyte remain small throughout their life-cycle.

They can only survive where moisture is available for significant periods, although some species are desiccation tolerant. Bryophytes first appeared during the early Palaeozoic. Plants are distinguished from green algae, from which they evolved, by having specialized reproductive organs protected by non-reproductive tissues. About three hundred plant species do not photosynthesize but are parasites on other species of photosynthetic plants.

All of these plants have eukaryotic cells with cell walls composed of cellulose, and most obtain their energy through photosynthesis, using light and carbon dioxide to synthesize food. They also include a few of their close relatives, often called bryophytes, of which mosses and liverworts are the most common. They include the vascular plants, plants with full systems of leaves, stems, and roots. Most familiar are the multicellular land plants, called embryophytes.

. 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. However, these are still often considered plants in many contexts. Since then, it has become clear that the Plantae as originally defined included several unrelated groups, and the fungi and several groups of algae were removed to new kingdoms.

In Linnaeus' system, these became the Kingdoms Vegetabilia (later Plantae) and Animalia. Aristotle divided all living things between plants, which generally do not move or have sensory organs, and animals. Plants are a major group of living things (about 300,000 species), including familiar organisms such as trees, flowers, herbs, and ferns. 0-521-64685-5.

Paperback, 247 pages ISBN. Cambridge University Press. Feeding the Ten Billion - Plants and Population Growth. (1998).

Evans, L.T. ISBN 0-13-651589-4. Englewood Cliffs, NJ: Prentice Hall. The Biology and Evolution of Fossil Plants.

(1993). & Taylor, Edith L. Taylor, Thomas N. ISBN 0-7167-1007-2.

Freeman and Company. H. New York: W. Biology of Plants (7th ed.).

(2005). Raven, Peter H., Evert, Ray F., & Eichhorn, Susan E. ISBN 1-56098-730-8. C.: Smithsonian Institution Press.

Washington, D. The Origin and Early Diversification of Land Plants: A Cladistic Study. (1997). Kenrick, Paul & Crane, Peter R.

Perennial: live for many growing seasons; continue to reproduce once mature. Biennial: live for two growing seasons; usually reproduce in second year. Annual: live and reproduce within one growing season. Magnoliophyta - flowering plants.

Gnetophyta - gnetae. Ginkgophyta - ginkgo. Cycadophyta - cycads. Pinophyta - conifers.

†Pteridospermatophyta - seed ferns. Seed plants (spermatophytes)