Crossotheca

Crossotheca is an extinct genus of seed ferns (Pteridospermatophyta) widespread in coal measures of Carboniferous, Permian and Triassic age,^[8] with possible Devonian remains known from Belgium.^[8][9] The type species is C. crepini, named and described in 1883 by R. Zeiller,^[1] and the genus is known from fossils found in Belgium (?), Canada, China, England, France, Hungary, Ireland, Poland and the United States.^[8]

Crossotheca Temporal range: Carboniferous-Triassic, 318.1–235.0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Specimen P 30369 (left) and the pollen bearing organs of C. hughesiana from Dudley, England
Reconstruction of C. höninghausi
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Division:	†Pteridospermatophyta
Class:	†Lyginopteridopsida
Order:	†Lyginopteridales
Genus:	†Crossotheca Zeiller (1883)[1]
Species
†C. boulayi Zeiller (1883)[1] †C. communis Lesquererfx †C. crepini Zeiller (1883) †C. fimbriata Kidston (1906)[2] †C. grievii Potonie (1954)[3] †C. höninghausi Johnson & Kidston (1911)[4][5] [originally Sphenopteris] †C. hughesiana Kidston (1906)[2] †C. kentuekiensis Stubbefield, Taylor & Daghlian (1982)[6] †C. kidstom? (nomen dubium) †C. kidstoni Crookall †C. pinnatifida Gutbier †C. sagittata Lesquererfx †C. schatzlarensis †C. reniformis †C. trichomanoides †C. trisecta Sellards
Synonyms
Sphenopteris höninghausi Brongniart (1849)[7]

One species, C. höninghausi, is the male fructification of Lyginodendron oldhami^[5][9] and the same species is the microsporangia-bearing member of Lyginopteris.^[5]

Description

A fertile Crossotheca branch shows the following features:^[2][8]

• 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).