Crossotheca is an extinct genus of seed ferns widespread in coal measures of Carboniferous, Permian and Triassic age, with possible Devonian remains known from Belgium. The type species is C. crepini,

Pteridosperms, also known as 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.