Drepanophycaceae is a family of extinct lycophytes[1] of Late Silurian to Late Devonian age (427 to 359 million years ago), found in North America, China, Russia, Europe, and Australia.
| Drepanophycaceae Temporal range:
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|---|---|
Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Lycophytes |
| Order: | †Drepanophycales |
| Family: | †Drepanophycaceae Kräusel & Weyland, 1949 |
| Genera | |
Description
editThe stems are 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.[2] Vascular bundle an exarch 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.[3]
Drepanophycaceae differs from a related family of the same period, Asteroxylaceae, in having vascularized microphylls;[3] see Drepanophycales for more details.
Genera
editThe genera in the family are:[2]
- 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
- 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)
Notes
edit- ^ "Drepanophycaceae". www.scientific-web.com. Archived from the original on March 1, 2012.
- ^ a b Hueber 1992, p. 491 (Baragwanathia) and 492 (Drepanophycus)
- ^ a b See tables 2 & 3 in Gensel (1992) for list of these anatomical details.
References
edit- P. G. Gensel (1992), "Phylogenetic relationships of the zosterophylls and lycopsids: evidence from morphology, paleoecology, and cladistic methods of inference", Annals of the Missouri Botanical Garden, 79 (3): 450–473, doi:10.2307/2399750, JSTOR 2399750
- F. M. Hueber (1992), "Thoughts on the early lycopsids and zosterophylls", Annals of the Missouri Botanical Garden, 79 (3): 474–499, doi:10.2307/2399751, JSTOR 2399751