Drepanophycaceae

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Drepanophycaceae
Temporal range: Late Silurian to Late Devonian
Scientific classification e
Kingdom: Plantae
Clade: Tracheophytes
Clade: Lycophytes
Class: Lycopodiopsida
Order: †Drepanophycales
Family: †Drepanophycaceae
Kräusel & Weyland, 1949
Genera

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.

Description[]

The 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[]

The 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[]

  1. ^ http://www.scientific-web.com/en/Biology/Plants/Lycopodiophyta/Drepanophycaceae.html Archived March 1, 2012, at the Wayback Machine
  2. ^ a b Hueber 1992, p. 491 (Baragwanathia) and 492 (Drepanophycus)
  3. ^ a b See tables 2 & 3 in Gensel (1992) for list of these anatomical details.

References[]

  • 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: 450–473, doi:10.2307/2399750
  • F. M. Hueber (1992), "Thoughts on the early lycopsids and zosterophylls", Annals of the Missouri Botanical Garden, 79: 474–499, doi:10.2307/2399751
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