The Taxonomic Status of Selanginella eatonii

Selaginella eatonii Hieron. ex Small has long been relegated to synonymy under S. armata Baker, but actually it is a distinct species. The plants are among the smallest known in this predominantly tropical genus. Selaginella eatonii and the West Indian S. armata are both members of subg. Stachygynandrum (Pal. Beauv.) Baker, which is characterized by having dorsiventrally flattened shoots comprising two lateral rows of larger leaves plus two medial rows of smaller leaves. According to Baker's (1883-1885) scheme of classification, S. eatonii is closely related to the other heterophyllous Selaginellae of eastern North America, namely S. apoda (L.) Spring, S. eclipes Buck, and S. ludoviciana A. Braun. When J. K. Small (1918, p. 67) originally described S. eatonii, he credited Hieronymus with being the author. No specimens of it were cited, although Small reported the plant as growing on limestone in the "Everglade Keys;" he also stated that the plant was first collected in 1903. The species is quite rare in South Florida.