The Ultrastructure of the Spores of the Devonian Plant Parka decipiens

The ultrastructure of the spores of Parka decipiens Flemingwas investigated by SEM and TEM. The spores are shown to havea structured wall consisting of two distinct layers, one ofwhich exhibits a lamellate organization. The deposition of thespore wall by a tapetum is suggested to account for these lamellae.Comparison is made between the spore ultrastructure of Parkaand that of algae and bryophytes. It is suggested that the sporewall of Parka bears some similarities with the lamellate exinefound in the Hepaticae. Parka decipiens, Devonian, fossil, spore wall, ultrastructure, lamellae, tapetum