A systematic revision of the neotropical species of nephrolepis schott

This study was a systematic revision of the neotropical species of Nephrolepis Schott. The genus has been plagued with chronic misapplication of epithets, misidentifications, and has not been critically revised since its recognition in 1834. This was the first detailed study of any portion of the genus utilizing modern taxonomic procedures. An initial classification was proposed from a study of morphological features using cluster analysis and principle coordinate analysis. These results were compared with species groups indicated by other categories of taxonomic evidence including palynology, gametophyte development and morphology, cytology, chemotaxonomy, phytogeography, and ecology. Artificial hybridization was also attempted in order to establish the hybrid origin of one taxon. Information from these additional data categories (except the gametophyte and hybridization studies) variously supported or conflicted with portions of the initial classification. Data from all of the categories were then integrated to produce a final phenetic classification. This final classification served as the basis for the taxonomic treatment. A conspectus of the entire genus was compiled as a pre-liminary step to future study and as a framework for indicating relationships of the neotropical species within the genus as a whole.

Relationships depicted by the initial morphological study were largely confirmed by data from palynology, cytology, chemo-taxonomy, phytogeography, and ecology. Gametophyte and hybridization studies did not reveal additional information of value in comparing species. Because the information from the other data categories largely supported the morphological relationships, the final classification was not radically different from the initial one.

Nine species were recognized in the final classification with the following relationships: Nephrolepis x averyi Nauman (an allotetraploid hybrid between N. biserrata (Swartz) Schott and N. exaltata (L.) Schott) and N. exaltata were the two most closely related species; N. rivularis (Vahl) Mett. ex Krug is most related to the former two species, but it is still a relatively distinct species; N. cordifolia (L.) Presl and N. occidentalis Kunze form a species pair most related to the preceding three species; N. pectinata (Willd.) Schott and N. pendula (Raddi) J. Smith form a species pair next most related to the preceding five species; and N. biserrata and N. multiflora (Roxb.) Jarret ex Morton form a distinct species pair well separated from the other species.