- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
A study of Pennsylvanian petrified seeds and seedlike megaspores has revealed new information on the structure of the megaspore membrane and associated tissues, and has provided characteristics useful for identifying seed fragments released from coals and shales by maceration. Layering and ornamentation may be observed in surface views of detached megaspore membranes, but clarity is greater if microtome sections are prepared. Fragments of the nucellus which sometimes remain associated with the megaspore membranes supplement these features and aid in the recognition of taxa. Genera studied which are recognizable from fragments of megaspore membrane are: Cardiocarpus, Conostoma, Codonospermum, Stephanospermum, Taxospermum, Pachytesta, Lepidocarpon, and Lepidostrobus.