The Thelypteris normalis Complex in the Southeastern United States

Abstract

The species of the Thelypteris normalis complex in the southeastern United States and the West Indies have long been acknowledged as taxonomically troublesome. The first person to monograph the group was Christensen (1913), who treated it under Dryopteris, subg. Cyclosorus. More recent workers have also recognized the integrity of the group, but generally have treated it as a subgroup of Thelypteris (Small, 1938; Wherry, 1943, 1964). The chief problems encountered by Christensen and others have been the extreme variability in the species and the large number of forms which are seemingly intermediate between species. Robert and Edward St. John, avid collectors of Florida ferns in the 1930's, added to the proliferation of names when they described numerous Florida endemics. The assiduousness of previous workers, however, has laid the groundwork for more detailed studies utilizing cytology and field-to-greenhouse transplants, an approach which I believe has clarified the systematics of the group. A revision of Thelypteris sect. Cyclosorus in the New World is currently being prepared for future publication. However, in order that the important conclusions of this study might be more immediately available to those with an interest in ferns of the southeastern United States and to those involved in the preparation of floras, it seems appropriate to publish a portion of the study dealing with the species of this area. Following a key to the species and varieties is a synopsis of the southeastern United States taxa, excluding T. totta (= T. gongylodes), which is only rather distantly related to species in the T. normalis complex. Important aspects of synonymy, habitat, distribution, and a discussion of