A Reconsideration of the Pennsylvanian Arthrophyte Sphenophyllum gilkineti Leclercq

A review is presented of the anatomy of the type specimen of Sphenophyllum gilkineti and of Leclercq's observations concerning it Similar stems subsequently discovered in North American coal balls are discussed and illustrated In view of the evidence presented by these specimens, which conclusively links the production of two-zoned secondary xylem with the disruption of normal cambial activity, there can be little doubt that S. gilkineti represents an abnormal growh form rather than a valid species