''Crossotheca'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

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 ...

of seed ferns (

Pteridospermatophyta Pteridospermatophyta, also called pteridosperms or seed ferns, are a polyphyletic grouping of extinct seed-producing plants. The earliest fossil evidence for plants of this type are the lyginopterids of late Devonian age. They flourished partic ...

) widespread in coal measures of

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

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 251.902 Mya. It is the s ...

and

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

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

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 ...

remains known from

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. 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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and the

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

Encyclopædia Britannica The is a general knowledge, general-knowledge English-language encyclopaedia. It has been published by Encyclopædia Britannica, Inc. since 1768, although the company has changed ownership seven times. The 2010 version of the 15th edition, ...

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 Unpublished taxonomic opinions.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

microsporangia A microsporangium () is a sporangium that produces 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 a ...

-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