BOSTONIA PERPLEXA GEN. ET SP. NOV., A CALAMOPITYAN AXIS FROM THE NEW ALBANY SHALE OF KENTUCKY

Bostonia perplexa, gen. et sp. nov., was collected from the Lower Mississippian Falling Run member of the Sanderson Formation. The single short segment of an axis, preserved as a petrifaction, contains at least three vascular columns, each with both primary and secondary tissues. Primary xylem is two or three ribbed, and contains several mesarch protoxylem strands. Gymnospermous secondary xylem is characterized by both uniseriate and multiseriate rays. The ground tissue is parenchymatous except for a few clusters of sclerotic cells. In its apparent polystelic nature, the specimen superficially resembles members of the Pennsylvanian to Permian Medullosaceae. All evidence currently available, however, leads to the conclusion that this species should be placed in the Upper Devonian to Lower Mississippian Calamopityaceae. It has not been determined with certainty whether the species is polystelic (in the sense of the Medullosaceae), or whether the apparent polystely is the result of stelar branching proximal to the level of branch divergence.