Rellimia Thomsonii (Progymnospermopsida) From the Middle Devonian of New York State

Rellimia thomsonii, a progymnosperm known from the Givetian of Europe and the USSR, is described from New York. The spiral branching pattern and once dichotomized fertile organs prove to be consistent characters separating Rellimia from Tetraxylopteris. Both are abundant in New York: the simpler Rellimia restricted to Givetian (Middle Devonian) strata, the more complex Tetraxylopteris to Frasnian (Upper Devonian) beds. The primary xylem of Rellimia is described for the first time. It is a three‐lobed protostele with a continuous mesarch protoxylem strand in each lobe. The anatomical description of Rellimia supports its morphological distinction from Tetraxylopteris and emphasizes their generic validity within the Aneurophytales.