title: Intergeneric hybridization and speciation between two leptosporangiate ferns.
abstract: The oosphere of Pteridium aquilinum is surrounded by a 'special membrane' which does not appear to resist the fertile spermatozoon of Gymnogramme calomelanos var. chrysophylla and monospermy results. Our hybridization findings also indicate that the membrane maintains speciation. The spermatozoon of Gymnogramme is strongly attracted but some injury is sustained during its passage through the mucilage of the archegonium neck. Nevertheless, rupture of the membrane, herein designated the cortical complex of speciation (CCS), is followed by expulsion of the oosphere-cytoplasm for which an osmotic mechanism is proposed.
mesh_terms: D003433:Crosses, Genetic; D006824:Hybridization, Genetic; D018521:Plant Physiological Phenomena; D010944:Plants / Q000648:ultrastructure