Drepanophycus
From Wikipedia, the free encyclopedia
| Drepanophycus Fossil range: Devonian: Lochkovian - Frasnian |
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Another species has been described: Drepanophycus colophyllus Grierson & Banks - but this has since been removed to the genus Haskinsia. |
Drepanophycus is a genus of extinct plants of the Division Lycopodiophyta of Early to Late Devonian age, found in Eastern Canada and Northeast USA, China, Russia, and various parts of Northern Europe and Britain.
[edit] Description
Extinct terrestrial vascular plants of the Devonian period. Stem of the order of several mm to several cm in diameter and several cm to a metre long, erect or arched, dichotomizing occasionally, furnished with true roots at the base. Vascular bundle plectostele, tracheids of primitive annular or helical type (so-called G-type). Leaves are unbranched thorn-shaped (i.e. with a wide base, tapering to a blunt point) microphylls several mm long with a single prominent vascular thread, arranged spirally to randomly on the stem. Sporangia borne singly on the upper leaf surface.
Drepanophycus differs from a closely related genus of the same period, Baragwanathia, in the position of the sporangia, the type of stele, and the arrangement and shape of the leaves; see Drepanophycaceae for more details.
It is more derived than the coexisting genus Asteroxylon, which has enations lacking vascules, in contrast to the true leaves of Drepanophycus.
[edit] References
- Dawson, J.W. (1859) On fossil plants from the Devonian rocks of Canada. Quarterly Journal of the Geological Society of London 15, 477-488.
- Göppert, H.R. (1852) Fossile Flora des Ubergangsgebirges. Verhandlungen der Kaiserlichen Leopoldinisch-Carolinischen Akademie der Naturforscher, Supplement des Bandes 14, 1-299.
- Li Cheng-Sen & Edwards D. (1995) A re-investigation of Halle's Drepanophycus spinaeformis Göpp. from the Lower Devonian of Yunnan Province, Southern China. Botanical Journal of the Linnean Society 118, 163-192.
