ACHLAMYDOCARPON VARIUS COMB. NOV.: MORPHOLOGY AND REPRODUCTIVE BIOLOGY

Abstract

Structurally preserved arborescent lycopsid fructifications are described from Pennsylvanian age strata in eastern Kentucky and southern Illinois. Achlamydocarpon varius comb. nov. is the name proposed for these cones and previously reported isolated megasporophylls described as Lepidostrobophyllum varius. The specimens range up to 3.5 cm long and represent cone apices. Megasporophylls are spirally arranged and attached to the cone axis at an acute angle. Megasporangia are large with a wall two cell layers thick. Each sporangium contains one large, presumably functional megaspore, and three smaller, abortive megaspores. Functional and abortive spores possess a prominent apical tuft (massa) that covers up to one‐third of the proximal surface of the spore. Sporoderm ultrastructure is detailed together with a comparison of morphologically similar sporae dispersae megaspores. The possible function of the megaspore massa is discussed as it relates to the reproductive biology of the cone.