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''Drepanophycus'' is a genus of extinct plants of the division
Lycopodiophyta The lycophytes, when broadly circumscribed, are a vascular plant (tracheophyte) subgroup of the kingdom Plantae. They are sometimes placed in a division Lycopodiophyta or Lycophyta or in a subdivision Lycopodiophytina. They are one of the olde ...
of Early to Late
Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...
age (around ), found in Eastern Canada and Northeast US, China, Russia, Egypt and various parts of Northern Europe and Britain.


Description

Extinct terrestrial
vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...
s 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 bundle actinostele,
tracheid A tracheid is a long and tapered lignified cell in the xylem of vascular plants. It is a type of conductive cell called a tracheary element. Angiosperms use another type of tracheary element, called vessel elements, to transport water through the ...
s 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)
microphyll In plant anatomy and evolution a microphyll (or lycophyll) is a type of plant leaf with one single, unbranched leaf vein. Plants with microphyll leaves occur early in the fossil record, and few such plants exist today. In the classical concep ...
s several mm long with a single prominent vascular thread, arranged spirally to randomly on the stem.
Sporangia A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their lif ...
borne singly on the upper leaf surface. ''Drepanophycus'' has similarities to the genus ''
Halleophyton ''Halleophyton'' is a genus of extinct vascular plants of the Early Devonian (Pragian, around ). Fossils were first found in the Posongchong Formation of eastern Yunnan, China. The plant had leafy aerial stems. The leaf bases completely covered ...
''. It differs from a closely related genus of the same period,
Baragwanathia ''Baragwanathia'' is a genus of extinct lycopsid plants of Late Silurian to Early Devonian age (), fossils of which have been found in Australia, Canada, China and Czechia. The name derives from William Baragwanath who discovered the first speci ...
, in the position of the sporangia, and the arrangement and shape of the leaves; see
Drepanophycaceae Drepanophycaceae is a family of extinct lycophytes of Late Silurian to Late Devonian age (), 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 ...
for more details. It is more derived than the coexisting genus ''
Asteroxylon ''Asteroxylon'' ("star-shaped xylem") is an extinct genus of vascular plants of the Division Lycopodiophyta known from anatomically preserved specimens described from the famous Early Devonian Rhynie chert and Windyfield chert in Aberdeenshire, ...
'', which has enations lacking vascules, in contrast to the true leaves of ''Drepanophycus''. ''Drepanophycus spinaeformis'' was first discovered in
Scotland Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...
; fossils have since been recovered in Russia (around Lake Shunet in the republic of
Khakassia Khakassia (russian: Хакасия; kjh, Хакасия, Хакас Чирі, ''Khakasiya'', ''Khakas Çiri''), officially the Republic of Khakassia (russian: Республика Хакасия, r=Respublika Khakasiya, ; kjh, Хакас Рес ...
), in the
Yunnan Yunnan , () is a landlocked province in the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is Kunming. The province borders the ...
province of the
People's Republic of China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones an ...
, and in
Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Medite ...
. They were among the earliest land plants,Palaeos Plants: Chlorobionta
growing to approximately 80 cm in height. The species is notably differentiated from other plants in the
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial no ...
by its thicker stems. Foliage is described as firm and spiny, though recovered fossils rarely retain leaf detail. The stomata of ''D. spinaeformis'' look similar to that of ''
Lycopodium ''Lycopodium'' (from Greek ''lykos'', wolf and ''podion'', diminutive of ''pous'', foot) is a genus of clubmosses, also known as ground pines or creeping cedars, in the family Lycopodiaceae. Two very different circumscriptions of the genus are i ...
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 circumporal area.


References

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External links


Ancient Land Plants
{{Taxonbar, from=Q5306962 Early Devonian plants Silurian plants Drepanophycales Lochkovian life Pragian life Emsian life Eifelian life Givetian life Frasnian life Middle Devonian plants Late Devonian plants Early Devonian first appearances Late Devonian genus extinctions Paleozoic life of Ontario Paleozoic life of New Brunswick Paleozoic life of Newfoundland and Labrador Paleozoic life of Nunavut Paleozoic life of Quebec Prehistoric lycophyte genera