Tetraxylopteris Schmidtii: Its Fertile Parts and Its Relationships Within the Aneurophytales

The fertile branching system of Tetraxylopteris is composed of successive “nodes” bearing opposite and decussately arranged, upcurved sporangial complexes. By means of the transfer technique the morphology of the sporangial complex was revealed. It consists of a main stalk which dichotomizes twice producing four major branches. Each of the four branches is further subdivided three times, the subdivisions being arranged alternately and pinnately. The ultimate divisions bear the sporangia singly and terminally. The sporangial complexes decrease in size distally and are more tightly curved at the apex. The sporangia are oblong-oval with an acute apex. The spores are identical to the dispersed spore taxon Rhabdosporites langii, Richardson. They are spherical, trilete and pseudosaccate with a fine granular ornament on the pseudosaccus. They are 75–176 μ in diameter and show developmental stages from young tetrads to separated, fully mature spores depending on the age of the sporangium from which they were obtained. This is the first account of spores in sporangia of Tetraxylopteris. The diagnosis of the genus and species are emended to include the new information and the order Aneurophytales is redefined.