Calamites is a genus of extinct arborescent (tree-like) horsetails to which the modern horsetails (genus Equisetum) are closely related. Unlike their herbaceous modern cousins, these plants were medium-sized trees, growing to a height of 10 meters (31 feet). They were persistant minor component of coal swamps of the Carboniferous period. In biology and ecology, extinction is the ceasing of existence of a species or group of species. ... Species Subgenus Equisetum Equisetum arvense - Field or Common Horsetail Equisetum bogotense - Andean Horsetail Equisetum diffusum - Himalayan Horsetail Equisetum fluviatile - Water Horsetail Equisetum palustre - Marsh Horsetail Equisetum pratense - Shade Horsetail Equisetum sylvaticum - Wood Horsetail Equisetum telmateia - Great Horsetail Subgenus Hippochaete Equisetum giganteum - Giant Horsetail Equisetum myriochaetum - Mexican Giant Horsetail Equisetum hyemale... Species Subgenus Equisetum Equisetum arvense - Field or Common Horsetail Equisetum bogotense - Andean Horsetail Equisetum diffusum - Himalayan Horsetail Equisetum fluviatile - Water Horsetail Equisetum palustre - Marsh Horsetail Equisetum pratense - Shade Horsetail Equisetum sylvaticum - Wood Horsetail Equisetum telmateia - Great Horsetail Subgenus Hippochaete Equisetum giganteum - Giant Horsetail Equisetum myriochaetum - Mexican Giant Horsetail Equisetum hyemale... A herb (pronounced urb in American English and hurb in British English) is a plant grown for culinary or medicinal value. ... Coal is a fossil fuel extracted from the ground either by underground mining, open-pit mining or strip mining. ... The Carboniferous is a major division of the geologic timescale that extends from the end of the Devonian period, about 340 million years ago (mya), to the beginning of the Permian period, about 280 mya. ...

Anatomy

The trunks of Calamites had a distinctive segmented, bamboo-like appearance and vertical ribbing. The branches, leaves and cones were all borne in whorls. The leaves were needle-shaped, with up to 25 per whorl. Genera Many, see text Bamboos are a group of woody perennial evergreen plants in the grass family Poaceae, subfamily Bambusoideae. ...

Their trunks produced secondary xylem, meaning they were made of wood. The vascular cambium of Calamites was unifacial, producing secondary xylem towards the stem center, but not secondary phloem. Categories: Plant physiology | Trees | Biology stubs ... Vascular cambium is a tissue found in the stems of perennial dicots. ... In vascular plants, phloem is the tissue that carries organic nutrients, particularly sucrose. ...

The stems of modern horsetails are typically hollow or contain numerous elongated air-filled sacs. Calamites was similar in that its trunk and stems were hollow, like wooden tubes. When these trunks buckled and broke, they could fill with sediment. This is the reason pith casts of the inside of Calamites stems are so common as fossils. Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ... FOSSIL is a standard for allowing serial communication for telecommunications programs under DOS. FOSSIL stands for Fido Opus Seadog Standard Interface Layer and was made by a group of Fidonet sysops to make their software work on different machines. ...

Reproduction

Calamites reproduced by means of spores, which were produced in small sacs organized into cones. They also known to have possesed massive, underground rhizomes, which allowed for the production of clones of one tree. This is the only group of trees of their period known to have a clonal habit. This type of asexual reproduction would allow them to spread quickly into new territory, in addition to aiding in anchoring them firmly in the unstable ground along rivers and in newly deposited delta sediments. The rhizomes of Calamites look quite similar to the stems in most cases, but have nodes that get progressively closer together as they get out approach the apical area (the growth tip that spreads outward through the soil). In botany, a rhizome is a horizontal, usually underground stem of a plant that often sends out roots and shoots from its nodes. ... As a word, clone was first coined by J.B.S. Haldane as subject for theoretical replication of a frog, though the term clone is derived from κλων, the Greek word for twig. In horticulture, the spelling clon was used until the twentieth century. ... Reproduction is the creation of one thing as a copy of, product of, or replacement for a similar thing, e. ... Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ...

Different forms

Calamites come in a variety of different "form genera". One type, Calamites suckowi, is distinguishable from other Calamites forms by its prominent, swollen nodes and relatively wide-spaced longitudinal ribs. Another example, Calamites cisti, has much smaller nodes and the ribs are typically closer together.

In addition, the distance between successive node lines on a Calamites suckowi specimen is typically much wider than the diameter. In other forms like Calamites cisti, the opposite is true or the specimen is just slightly wider than the diameter.

Extiction and classification

The genus Calamites has been placed in the plant division Equisetophyta (formerly known as Sphenophyta) and family Calamitaceae. They finally became extinct in the Lower Permian, a time which, however, also saw the origin of the family Equisetaceae, to which the only living sphenophyte genus Equisetum belongs. Classes Equisetopsida The division Equisetophyta is a taxon in the kingdom Plantae containing primitive land plants. ... The Permian is a geologic period that extends from about 280 to 248 million years before the present (mya). ... Species Subgenus Equisetum Equisetum arvense - Field or Common Horsetail Equisetum bogotense - Andean Horsetail Equisetum diffusum - Himalayan Horsetail Equisetum fluviatile - Water Horsetail Equisetum palustre - Marsh Horsetail Equisetum pratense - Shade Horsetail Equisetum sylvaticum - Wood Horsetail Equisetum telmateia - Great Horsetail Subgenus Hippochaete Equisetum giganteum - Giant Horsetail Equisetum myriochaetum - Mexican Giant Horsetail Equisetum hyemale...

See also

• Archaeopteris

Archaeopteris is an extinct genus of tree-like ferns that many scientists believe to be the first tree. ...

References

• How large are the giant horsetails? (http://www.fiu.edu/~chusb001/GiantEquisetum/HowLarge.html)
• Sphenophyta: Fossil Record (http://www.ucmp.berkeley.edu/plants/sphenophyta/sphenofr.html)
• Stewart, W. N. Paleobotany and the Evolution of Plants. Cambridge University Press, Cambridge (1983).
• Davis, Paul and Kenrick, Paul. Fossil Plants. Smithsonian Books (in association with the Natural History Museum of London), Washington, D.C. (2004). ISBN 1588341569