Selaginella diffusa (C.Presl) Spring, Bull. Acad. Roy. Sci. Bruxelles

Smith, Alan R. & Kessler, Michael, 2018, Prodromus of a fern flora for Bolivia. III. Selaginellaceae, Phytotaxa 344 (3), pp. 248-258 : 252-253

Selaginella diffusa (C.Presl) Spring, Bull. Acad. Roy. Sci. Bruxelles 10: 143. 1843.

Range: —Mountains from Costa Rica east to Suriname and Trinidad, south to Bolivia (CO, LP).

Ecology: —Common; terrestrial, prostrate with erect branch tips, sometimes forming large colonies, in humid forests, on steep banks, on logs, and among rocks; 400–3200 m.

Notes: —A confusingly variable species, especially in size, but also in degree of development of auricles on the axillary leaves. A related species, Selaginella lingulata Spring , from Colombia to Peru, has been reported from Bolivia by Alston et al. (1981), who cited Bang 909 ( US; but cited by them as S. diffusa in BM!) and Tate 1076 ( US), but we believe that both collections, the former seen in UC, the latter determined by M. Sundue in NY, are better identified as S. diffusa ; Tryon & Stolze (1994) echoed the presence of S. lingulata in Bolivia, without citing specimens. It differs from S. diffusa by its basally ciliolate lateral leaves without auricles (vs. lateral leaves long-ciliate, biauriculate, cilia often 2 or more cells).

Another closely related species is S. horizontalis (C.Presl) Spring , from Costa Rica to Ecuador; it differs from S. diffusa in having narrowly oblong lateral leaves (vs. ovate), in having unicellular cilia at the base of the lateral leaves (vs. mostly 2- or more celled), and having medial leaves aristate (vs. acute or acuminate), each with a single auricle (vs. with two auricles, the inner one sometimes rudimentary).