Equisetopsida
| Equisetopsida | ||||||||||||
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Equisetum telmateia |
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| Scientific name | ||||||||||||
| Equisetopsida | ||||||||||||
| C. Agardh |
The Equisetopsida (also called Sphenopsida in paleobotanical literature ) are a class of vascular plants . The Equisetopsida have their origin in the Devonian , their greatest diversity in the hard coal forests of the Carboniferous and are recently only represented by the horsetail .
features
Members of the Equisetopsida are characterized by stems divided into nodes with internodes in between . The trunks of some fossil groups, such as the kalamites of the coal forests , were lignified and reached heights of up to 30 meters and a trunk diameter of up to 1 meter, while other groups were more herbaceous and remained significantly smaller. The trunks are usually hollow inside. The internodes are m. o. w. clearly ribbed, which reflects the course of vascular bundles . The trunks arise from a rhizome that forms adventitious roots at the nodes . The leaves are always arranged in a whorl . The leaves of the horsetail are subphrate (microphylls), while the wedge -shaped leaves usually widened like a wedge with branching leaf veins. The spores are formed in sporangia, which are in sporangia carriers and are usually arranged like cones as strobili . The sporangia are either in specially designed sprouts ( sporophylls ) and separate from the photosynthetically active trophophylls (e.g. horsetail ) or as a “flower” at the end of the trophophylls (e.g. bowmanites type). In some fossil species, the sporangia levels were either heterosporous or isosporous (including the more recent horsetail).
Systematics
External system
The Equisetopsida are part of the ferns in the narrower sense ("Monilophytes", excluding the club moss plants formerly included in the fern plants) and a sister group to a clade , the two relic groups of poor species, the Psilotopsida with the fork-leaf plants (Psilotaceae) and the adder tongue plants (Ophioglossaceae) Marattiopsida with the only family Marattiaceae, as well as the more species-rich real ferns. The position of the Equisetopsida was controversial for a long time, earlier studies saw them partly as a sister group of the Maratticeae or the real ("leptosporangiaten") ferns. The current placement is supported by morphological studies (also using fossil taxa) and genetic studies.
| Vascular plants (tracheophyta) |
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Internal system
The internal systematics is inconsistent in the literature, as most of the groups are only available in fossil form. Taylor et al. In 2009 there are three subgroups:
- Pseudoborneales (Devonian)
- Wedge-leaved plants [Sphenophyllales] (Devon to triad )
- Equisetales (Devonian to recent)
Pseudoborneal
The pseudoborneales are monotypic (only Pseudobornia ursina ). Pseudobornia formed up to 30 m high articulated, lignified, hollow trunks. In the first branching order, only 1 to 2 branches per node were formed, which in the second branching order were cross-opposite (dekussed) and finally arranged in pseudo-two-lines. The leaves are formed only in the final branches and are arranged in whorls of four. Each leaf consists of a twofold forked petiole and correspondingly four heavily slashed leaf blades. The fertile sections sit at the end of the primary branches and form sporangia carriers. The sporangia are heterosporous. The systematic position of the pseudoborneales is unclear, but due to their age they can be regarded as representatives of the original Equisetopsida.
Wedge-leaf plants
The wedge-leaf family can be identified as early as the late Devonian, but they only become very common in the undergrowth of the hard coal forests in the Carboniferous and can be identified up to the Triassic. They are herbaceous plants whose growth is interpreted as creeping to climbing. The shoots branch out forked and carry 6-9 (-18) leaves per whorl through the triarchy vascular bundles . The leaves have forked branching veins and a mostly wedge-like shape (name!). The sporangia are loosely arranged in strobili or cone-like and always isospore.
Equisetales
Just like the wedge-leaf family, the first representatives of the Equisetales , the Kalamites, appear in the late Devonian, but only become dominant in the Carboniferous and are tree-like there. However, the kalamites disappeared as early as the Permian, while Tchernoviaceae and Gondwanastachyaceae can be found until the Cretaceous and Equisetaceae still exist today. The Calamitaceae are tree-like plants with hollow branched trunks. The leaves are lanceolate to needle-like in whorls. The sporangia are isosporous or heterosporous and are cone-like in sporangia carriers over bracts. Tchernoviaceae and Gondwanastachyaceae do not form isospore sporangia in strobili, but in fertile internodes, in which the sporangia are in table-shaped sporangia carriers. In the Equisetaceae, the leaves are sheath-like and sub-like with a maximum of one leaf vein per leaflet (microphyll). They form cone-like strobili without bracts, in which sporangia stand in table-shaped sporangia carriers. Fossil Equisetaceae are often classified as Equisetites , while the recent ones all belong to the genus Equisetum .
Receipts and further information
literature
- Chester A. Arnold : An Introduction to Paleobotany. Dodo Press, 2007, ISBN 978-1-4067-1861-4 (Reprint; Original: McGraw-Hill, New York 1947).
- Wilson N. Stewart , Gar W. Rothwell : Paleobotany and the Evolution of Plants. 2nd Edition. Cambridge University Press, Cambridge et al. 1993, ISBN 0-521-38294-7 .
- Peter Sitte , Elmar Weiler , Joachim W. Kadereit , Andreas Bresinsky , Christian Körner : Textbook of botany for universities . Founded by Eduard Strasburger . 35th edition. Spektrum Akademischer Verlag, Heidelberg 2002, ISBN 3-8274-1010-X .
- Thomas N. Taylor, Edith L. Taylor, Michael Krings: Paleobotany. The Biology and Evolution of Fossil Plants . 2nd Edition. Elsevier / Academic Press, Amsterdam et al. 2009, ISBN 978-0-12-373972-8 .
Individual evidence
- ↑ Kathleen M. Pryer, Eric Schuettpelz, Paul G. Wolf, Harald Schneider, Alan R. Smith, Raymond Cranfill: Phylogeny and evolution of ferns (Monilophytes) with a focus on the early leptosporangiate divergences. In: American Journal of Botany. Volume 91, No. 10, 2004, pp. 1582-1598, DOI: 10.3732 / ajb.91.10.1582 .
- ↑ Andrés Elgorriaga, Ignacio H. Escapa, Gar W. Rothwell, Alexandru MF Tomescu, N. Rubén Cúneo (2018): Origin of Equisetum: Evolution of horsetails (Equisetales) within the major euphyllophyte clade Sphenopsida. American Journal of Botany 105 (8): 1-18. doi: 10.1002 / ajb2.1125
- ↑ Carl J. Rothfels, Fay-Wei Li, Erin M. Sigel, Layne Huiet, Anders Larsson, Dylan O. Burge, Markus Ruhsam, Michael Deyholos, Douglas E. Soltis, C. Neal Stewart, Jr., Shane W. Shaw , Lisa Pokorny, Tao Chen, Claude dePamphilis, Lisa DeGironimo, Li Chen, Xiaofeng Wei, Xiao Sun, Petra Korall, Dennis W. Stevenson, Sean W. Graham, Gane KS. Wong, Kathleen M. Pryer (2015): The evolutionary history of ferns inferred from 25 low-copy nuclear genes. American Journal of Botany 102 (7): 1089-1107. doi: 10.3732 / ajb.1500089
- ↑ Weston Testo & Michael Sundue (2016): A 4000-species dataset provides new insight into the evolution of ferns. Molecular Phylogenetics and Evolution 105: 200-211. doi: 10.1016 / j.ympev.2016.09.003
