Calamites
| Calamites | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Upper carbon to lower perm | ||||||||||||
| 318 to 272 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Calamites | ||||||||||||
| Brongn. |
The Kalamites ( Calamites ) are a genus of extinct tree-like horsetail , which are closely related to today's horsetail. In contrast to today's herbaceous representatives of horsetail, the kalamites were medium-sized trees up to 10 (rarely 20 to 30) meters in height. They were common but not dominant inhabitants of the coal swamps of the Carboniferous Period and in the forests of the Permian Period . Along with other extinct horsetail relatives, they belong to the Calamitaceae family .
anatomy
The calamite trunks showed a characteristic appearance with bamboo-like segmentation and vertical ribs. Both branches and leaves as well as spore cones stood in whorls . The up to 25 leaves per whorl were needle-shaped.
The trunks showed secondary growth in thickness , so they were made of wood . The cambium formed only secondary xylem and no phloem (“unifacial” cambium).
The stems of today's horsetail are typically hollow or contain elongated air sacs. The trunks of the Kalamites were also hollow and formed wooden tubes. Through fracture points in the trunks, sediments could penetrate the interior and so, as it were, fossil "casts" of the interior were created.
Reproduction
The kalamites multiplied by spores , the sporophylls ( sporangia carriers ) being combined to form cones. It is also known that they had massive underground rhizomes , which allowed the formation of clones of a tree. This makes them the only known vegetatively reproducing trees of that time. Like today's trees (e.g. willows and alders ) with the formation of root brood, they encountered the unstable soil conditions on river banks and in alluvial lands. Mostly, the rhizomes of the kalamites look similar to lying trunks, but the nodes move closer and closer together the closer they get to the tip of the shoot.
Different shapes
Various forms of kalamites, classified as species , are known. One of these forms, Calamites suckowi , is characterized by conspicuous, swollen trunk nodes and relatively large distances between the longitudinal ribs. In contrast, Calamites cisti shows much slimmer nodes and tighter ribs. In addition, the internodes of C. suckowi are typically much longer than they are wide, while those of C. cisti are at most as long as they are wide.
Extinction and Kinship
The genus Calamites and with them the family Calamitaceae died out in the Lower Permian , at a time when their sister family, the horsetail family (Equisetaceae), which contains the only representatives of the division of Equisetophyta still alive today .
literature
- Stewart, WN 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, DC (2004). ISBN 1-58834-156-9
Web links
- Calamites in the Mineralienatlas WiKi
- Sphenophyta *: Fossil Record of the University of Berkeley (* = Equisetophyta)