A Reinterpretation of Ophioglossum dendroneuron E. P. St. John

Ophioglossum dendroneuron E. P. St. John was described from Florida, and characterized by having a complex venation pattern with small areoles contained within larger areoles. W. Wagner and Mesler interpreted this as a distinct species; however, the present investigation alters this conception and the taxon O. dendroneuron is reinterpreted as a form of O. nudicaule L. fils. Extensive field and culture chamber observations show a transition from small-bladed forms with simple venation involving few or no included veinlets, to large-bladed forms with complex venation involving numerous included veinlets, some of which join to form secondary areoles. The latter bireticulate condition is transitional toward the venation found in O. engelmannii Prantl.