Drepanophycaceae
Encyclopedia
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.
s 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
, tracheid
s of primitive annular or helical type (so-called G-type). Leaves are unbranched microphyll
s 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 microphyll
s; see Drepanophycales
for more details.
Lycopodiophyta
The Division Lycopodiophyta is a tracheophyte subdivision of the Kingdom Plantae. It is the oldest extant vascular plant division at around 410 million years old, and includes some of the most "primitive" extant species...
of Late Silurian
Silurian
The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
to Late Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
age , found in North America, China, Russia, Europe, and Australia.
Description
Extinct terrestrial vascular plantVascular plant
Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...
s of the Silurian
Silurian
The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
to Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
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
Stele
A stele , also stela , is a stone or wooden slab, generally taller than it is wide, erected for funerals or commemorative purposes, most usually decorated with the names and titles of the deceased or living — inscribed, carved in relief , or painted onto the slab...
, tracheid
Tracheid
Tracheids are elongated cells in the xylem of vascular plants that serve in the transport of water and mineral salts. Tracheids are one of two types of tracheary elements, vessel elements being the other. All tracheary elements develop a thick lignified cell wall, and at maturity the protoplast...
s of primitive annular or helical type (so-called G-type). Leaves are unbranched microphyll
Microphyll
The terminology of fossil plants is in places a little confusing. In the discipline's 200+ year history, certain concepts have become entrenched, even though improved understanding has threatened the foundations upon which they are based...
s several mm to 2 cm or more long with a single prominent vascular thread, arranged spirally to randomly on the stem. Homosporous sporangia
Sporangium
A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle...
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 microphyll
Microphyll
The terminology of fossil plants is in places a little confusing. In the discipline's 200+ year history, certain concepts have become entrenched, even though improved understanding has threatened the foundations upon which they are based...
s; see Drepanophycales
Drepanophycales
Drepanophycales is an order of extinct plants of the Division Lycopodiophyta of ?Late Silurian to Late Devonian age , found in North America, China, Russia, Europe, and Australia. Sometimes known as the Asteroxylales or Baragwanathiales....
for more details.
List of genera
- DrepanophycusDrepanophycusDrepanophycus 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, Egypt and various parts of Northern Europe and Britain.-Description:...
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
- BaragwanathiaBaragwanathiaBaragwanathia is a genus of extinct plants of the division Lycopodiophyta of Late Silurian to Early Devonian age , fossils of which have been found in Australia, Canada and China.-Description:...
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)