| Drepanophycus | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Lycophytes |
| Order: | †Drepanophycales |
| Family: | †Drepanophycaceae |
| Genus: | †Drepanophycus Göpp., 1852 |
| Species | |
Another species has been described:Drepanophycus colophyllus Grierson & Banks - but this has since been removed to the genusHaskinsia. | |
Drepanophycus is a genus of extinct plants of the divisionLycopodiophyta of Early to LateDevonian age (around420 to 370 million years ago), found in Eastern Canada and Northeast US, China, Russia, Egypt and various parts of Northern Europe and Britain.
Extinct terrestrialvascular plants of the Devonian period. Stem of the order of several mm to several cm in diameter and several cm to a metre long, erect or arched, dichotomizing occasionally, furnished with true roots at the base. Vascular bundleactinostele,tracheids of primitive annular or helical type (so-called G-type). Leaves are unbranched thorn-shaped (i.e. with a wide base, tapering to a blunt point)microphylls several mm long with a single prominent vascular thread, arranged spirally to randomly on the stem.Sporangia borne singly on the upper leaf surface.
Drepanophycus has similarities to the genusHalleophyton.[1] It differs from a closely related genus of the same period,Baragwanathia, in the position of the sporangia, and the arrangement and shape of the leaves; seeDrepanophycaceae for more details. It is more derived than the coexisting genusAsteroxylon, which hasenations lacking vascules, in contrast to the true leaves ofDrepanophycus.
Drepanophycus spinaeformis was first discovered inScotland; fossils have since been recovered inRussia (aroundLake Shunet in the republic ofKhakassia), in theYunnan province of thePeople's Republic of China, and inEgypt. They were among the earliest land plants,[2] growing to approximately 80 cm in height. The species is notably differentiated from other plants in thegenus by its thicker stems. Foliage is described as firm and spiny, though recovered fossils rarely retain leaf detail. Thestomata ofD. spinaeformis look similar to that ofLycopodium japonicum. They both consist of two large guard cells and pore, and are anomocytic. There were two small guard cells surrounded by two large similarly shaped subsidiary cells (paracytic) deriving from a pronounced elliptical cuticular ledge on the surface of the guard cells surrounding a thickened circumpolar area.
