Drepanophycales

Drepanophycales Temporal range: late Silurian to Devonian PreЄ Є O S D C P T J K Pg N
Asteroxylon mackiei".
Scientific classification
Kingdom:	Plantae
Division:	Lycopodiophyta
Class:	Lycopodiopsida
Order:	Drepanophycales † Pic-Serm, 1958
Families
Asteroxylaceae Drepanophycaceae

Drepanophycales is an order of extinct plants of the Division Lycopodiophyta of ?Late Silurian to Late Devonian age (around 430 to 360 million years ago), found in North America, China, Russia, Europe, and Australia. Sometimes known as the Asteroxylales or Baragwanathiales.

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 actinostele, tracheids of primitive annular or helical type (so-called G-type). Stem clothed in either microphylls (leaves with a single vascular thread or 'vein'), or with leaf-like enations (unvascularized projections) with a vascular trace into the base of each enation. Homosporous, with sporangia borne singly and dehiscing by a single slit.^[1]

List of families

• Drepanophycaceae
  • stem with microphylls
• Asteroxylaceae
  • stem with unvascularized enations

Notes

1. The anatomical details for the genera in the included families are tabulated by Gensel (1992) tables 2 & 3.

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
• Pichi-Sermolli, R.E.G. (1958). The higher taxa of Pteridophyta and their classification. In: Systematics of today. (O. Hedberg, ed.). Uppsala Universitets Årsskrift 6:70-90.