Equisetophyta - Reference Center

Columbia Encyclopedia entry: Equisetophyta

Equisetophytaĕk′wəsətŏf'ətə, small division of the plant kingdom consisting of the plants commonly called horsetails and scouring rushes. Equisetum, the only living genus in this division, is descended evolutionarily from tree-sized fossil plants. There are about 30 species, distributed in every continent except Australia and Antarctica and in every climate from the tropics to the arctic. The plants, which generally grow in moist places, have roots and ribbed green stems, the surface of which is impregnated with silica crystals. Their abrasive texture made them useful in former times for scouring, hence their common name. Most species have numerous whorled branches that lend the plant a plumed or feathery appearance, thus giving rise to their other common name, horsetail. The scalelike nonphotosynthetic leaves are joined together to form a fringed whorl that encircles the stem at regular intervals; the green stems and branches are the photosynthetic organs. The stem has no cambium or secondary growth. It consists of a silica-impregnated epidermis, a cortex, and a central structure called a stele that contains a ring of vascular bundles, consisting of xylem and phloem. The conspicuous plant form of Equisetum, which may be more than 3 ft (1 m) high in some species, represents the diploid sporophyte generation. A cone, or strobilus, at the apex of the sporophyte stem bears spore-producing structures. Upon germination, the spores produce a green, frilled, thumbnail-sized haploid plant form, the gametophyte; specialized structures on the mature gametophyte, the archegonia and antheridia, produce, respectively, eggs and sperms. As in mosses, the sperm swims to the egg through a film of water, attracted by specific chemical substances. A zygote, formed as the result of fertilization, develops into green sporophytes to complete the life cycle. The order Calamitales contains plants known only from fossil remains so abundant in coals and associated shales from the Carboniferous period that it is assumed that they formed a major part of the vegetation that later became compressed into coal. The plants of the genus Calamites may have reached a height of 100 ft (30 m).

Wikipedia search results for: Equisetopsida

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Equisetopsida (redirected from Equisetophyta), or Sphenopsida, is a class of plants with a fossil record going back to the Devonian. Living species are commonly known as horsetails and typically grow in wet areas, with needle-like leaves radiating at regular intervals from a single vertical stem. Equisetopsida is placed in the botanical division of ferns, though sometimes regarded as a separate division Equisetophyta. The Sphenophytes comprise photosynthesising, "segmented", hollow stems, sometimes filled with pith. At the junction between each segment is a whorl of leaves. In the only extant genus Equisetum, these are small leaves with a singular...more »

Columbia Encyclopedia search results: Equisetophyta

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horsetail
Horsetail, any plant of the genus Equisetum [Lat.,=horse bristle], the single surviving genus of a large group (Equisetophyta) of primitive vascular plants. Like the ferns and club mosses, rel...
rush
Rush, name for tall, grasslike plants of various families, many of which have hollow stems. The true rushes belong to the family Juncaceae, one of the oldest families of plants, closely relate...
plant
Plant, any organism of the plant kingdom, as opposed to one of the animal kingdom or of the kingdoms Fungi, Protista, or Monera in the five-kingdom system of classification. (A more recent sys...

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