Drepanophycaceae
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Fossil
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Drepanophycaceae is a family of extinct plants of the division Lycopodiophyta of Late Silurian to Late Devonian age, found in North America, China, Russia, Europe, and Australia.
[edit] Description
Extinct terrestrial vascular plants of the Silurian to Devonian periods. Stem of the order of several mm to several cm in diameter and several cm to several metres long, erect or arched, dichotomizing occasionally, furnished with true roots at the base. Vascular bundle an exarch plectostele or actinostele, tracheids of primitive annular or helical type (so-called G-type). Leaves are unbranched microphylls several mm to 2 cm or more long with a single prominent vascular thread, arranged spirally to randomly on the stem. Homosporous sporangia borne singly on the upper leaf surface or in an axillary position.
Differs from a related family of the same period, Asteroxylaceae, in having vascularized microphylls; see Drepanophycales for more details.
[edit] List of genera
- Drepanophycus Göppert (type genus)
- microphylls short, tapering rapidly from wide base (thorn-shaped)
- microphylls arranged spirally or randomly on stem
- sporangia borne on upper surface of microphylls
- vascular bundle plectostele
- Baragwanathia Lang & Cookson
- microphylls long, not tapering over most of length (strap-shaped)
- microphylls arranged spirally on stem
- sporangia borne axially (whether on microphylls or on stem is not known)
- vascular bundle actinostele
