| details |
Late Pennsylvanian |
|
USA |
Zimmerman,R.P. The ultrastructure of Paleozoic megaspores membranes. |
1970 |
| details |
Late Pennsylvanian |
|
USA |
Kedves,M. Tranmission Electron Microscopy of the Fossil Gymnosperm Exines. |
1994 |
| original |
Late Carboniferous |
|
Illinois |
Taylor,T.N. et al. On the structure and relationships of a new Pennsylvanian species of the seed Pachytesta. |
1969 |
| details |
Carboniferous |
|
Illinois |
Taylor,T.N. et al. Pollination biology and reproduction in early seed plants. |
1979 |
| details |
Carboniferous |
|
Nd |
Chaloner,W.G. et al. Heterospory: Cul-de-Sac or pathway to the seed? (In: Pollen and Spores, Patterns of Diversification. S.Blackmore and S.H.Barnes, editors) |
1991 |