Reconstructing the Pennsylvanian-age filicalean fern Botryopteris tridentata (Felix) Scott

Numerous anatomically preserved fragments of the Middle Pennsylvanian age f ilicalean fern, Botryopteris tridentata, occur in coal balls collected at t he Pittsburgh and Midway Coal Company mine near Baxter Springs, Kansas. Inc luded are the first fertile specimens of the species, evidence of complete vegetative frond architecture, and fronds that are specialized for vegetati ve propagation. Rhizomes are erect and unbranched, have helical phyllotaxis and short internodes, and typically display an ectophloic solenostele. Fro nds are tripinnately compound with lobed pinnules that have open, dichotomo us venation. Fertile pinnae or individual pinnules are interspersed among v egetative frond segments and produce sori of annulate sporangia beneath vei ns on the abaxial pinnule surface. Fertile pinnule lobes are rolled toward the abaxial surface to enclose the sori. Sporangia have a horizontally elon gated biseriate annulus located near the short broad stark and produce tetr ahedral-shaped trilete spores with coarse spines. Epiphyllous branches dive rge from the stipe or rachis, and some fronds produce only branches. This f ern is reconstructed as having short stems. Helically arranged fronds are e ither pinnately dissected with lobed vegetative pinnules and abaxially roll ed fertile pinnules or are specialized for vegetative propagation. The latt er functioned as the foliar equivalent of stolons. While some characters of the B, tridentata plant are similar to those of Botryopteris forensis, gen eritype of the Botryopteridaceae, others are more comparable to those of Ps alixochlaena cylindrica, generitype of Psalixochlaenaceae, suggesting the n eed for reevaluation of systematic relationships among species of the Botry opteridaceae and Psalixochlaenaceae.