Studies in the Trigonocarpales. Part I. Pachytesta vera, a New Species from the Des Moines Series of Iowa

Publisher Website
Google Scholar
Abstract
Seeds with structure preserved, from the Des Moines Series of Iowa (Upper Carboniferous), are identified as a new species of pteridospermous seed, P. vera. The seeds are large, 6.5 cm. long by 3.5 cm. in diam.; the nucellus is stalked and free from the single integument; a single vascular strand entering the base of the seed supplies both integument and nucellus. The integument is composed of an inner fleshy layer, a stony layer, and an outer fleshy layer; 3 longitudinal ribs, radial extensions of the stony layer, extend from base to apex. The nucellus terminates in a short beak which, extending into the micropyle, provides an opening into the unspecialized pollen chamber, within which occur many pollen grains of the Florinites-type. Eight or more groups of non-functional megaspores occur within the nucellus. A single large functional megaspore is represented by its conspicuous membrane. Characteristics of the genus are revised relative to the "double" vascular system of the integument, the intermeshing of integument and nucellus, and the generic significance of sclerotic tissue in the outer parts of the integument.