''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 n ...

of seed ferns ( Pteridospermatophyta) widespread in coal measures of Carboniferous,

Permian The Permian ( ) is a geologic period and 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 period of the Pale ...

and

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

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 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 ...

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 ...

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

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...

, China,

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Poland Poland, officially the Republic of Poland, , is a country in Central Europe. Poland is divided into Voivodeships of Poland, sixteen voivodeships and is the fifth most populous member state of the European Union (EU), with over 38 mill ...

and the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

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

Encyclopædia Britannica The ( Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various ...

'' ( 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 ...

-bearing member of ''

Lyginopteris ''Lyginopteris'' is a genus of Late Carboniferous seed fern A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants ...

''.

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