''Drepanophycus'' is a genus of extinct plants of the division Lycopodiophyta of Early to Late

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

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 (; ), are plants that have lignin, lignified tissues (the xylem) for conducting water and minerals throughout the plant. They also have a specialized non-lignified Ti ...

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 Lignin, lignified cell in the xylem of Tracheophyta, vascular plants. It is a type of conductive cell called a tracheary element. Angiosperms also use another type of conductive cell, called vessel elements, to t ...

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 concept of ...

s several mm long with a single prominent vascular thread, arranged spirally to randomly on the stem.

Sporangia A sporangium (from Late Latin, ; : sporangia) is an enclosure in which spores are formed. It can be composed of a unicellular organism, single cell or can be multicellular organism, multicellular. Virtually all plants, fungus, fungi, and many ot ...

borne singly on the upper leaf surface. ''Drepanophycus'' has similarities to the genus '' Halleophyton''. 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; see Drepanophycaceae for more details. It is more derived than the coexisting genus '' Asteroxylon'', 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. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

; fossils have since been recovered in

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

(around Lake Shunet in the republic of Khakassia), in the

Yunnan Yunnan; is an inland Provinces of China, province in Southwestern China. The province spans approximately and has a population of 47.2 million (as of 2020). The capital of the province is Kunming. The province borders the Chinese provinces ...

province of the

People's Republic of China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, and in

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

. 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 (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

by its thicker stems. Foliage is described as firm and spiny, though recovered fossils rarely retain leaf detail. The

stomata In botany, a stoma (: stomata, from Greek ''στόμα'', "mouth"), also called a stomate (: stomates), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange between the internal air spa ...

of ''D. spinaeformis'' look similar to that of '' Lycopodium 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.

References

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External links

Ancient Land Plants
{{Taxonbar, from=Q5306962 Early Devonian 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