''Crossotheca'' is an extinct

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 nom ...

of seed ferns (

Pteridospermatophyta The term Pteridospermatophyta (or "seed ferns" or "Pteridospermatopsida") is a polyphyletic group of extinct seed-bearing plants (spermatophytes). The earliest fossil evidence for plants of this type is the genus ''Elkinsia'' of the late Devonia ...

) widespread in coal measures of Carboniferous,

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last ...

and

Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

age,Andrews, N. H. (1970). Index of Generic Names of Fossil Plants, 1820-1965. ''Geological Survey Bulletin'' 1-354 with possible Devonian remains known from

Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...

. The type species is ''C. crepini'', named and described in 1883 by R. Zeiller, and the genus is known from fossils found in Belgium (?),

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, China,

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Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...

and the

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. One species, ''C. höninghausi'', is the male fructification of '' Lyginodendron oldhami''"Palaeobotany," ''

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'' ( 11th ed.), v. 21, 1911, p. 536, fig. 28.Jud, N. A. (2011). Unpublished taxonomic opinions. and the same species is the

microsporangia Microsporangia are sporangia that produce microspores that give rise to male gametophytes when they germinate. Microsporangia occur in all vascular plants that have heterosporic life cycles, such as seed plants, spike mosses and the aquatic fe ...

-bearing member of '' Lyginopteris''.

Description

A fertile ''Crossotheca'' branch shows the following features: *The branch tips are slightly expanded into a circular or paddle-shaped limb. *At the tip of each branch there are a few bilocular sporangia attached together. *Each sporangium contains a number of microspores (pollens).

References

Pteridospermatophyta Carboniferous plants Permian plants Triassic plants Prehistoric plants Prehistoric plant genera Fossil taxa described in 1883 {{Triassic-plant-stub