Monographs Details: Selaginella
Authority: Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
Description:Genus Description - Plants terrestrial or epipetric, rarely epiphytic (not ours), prostrate and creeping to somewhat ascending or fully erect, slightly to much-branched; stems with abundant very small leaves, iso-phyllous and tightly imbricately arranged spirally in several ranks, or more commonly anisophyllous in four ranks, two lateral ranks of larger spreading leaves and two ranks of appressed and ascending median leaves on upper side of the stem, and axillary leaves in axils of branches; rhizophores (roots) either basal or from nodes (branchings), dichotomously branched on touching the ground; leaves orbicular to linear with a single vein and a minute ligule, leaves often ending in a hairlike tip (seta), entire to ciliate-denticulate, glabrous or rarely hispid on upper leaf surface; sporangia sessile, generally in 4-sided strobili terminal on branches, the sporophylls 4-ranked and slightly modified from the vegetative leaves, usually monomorphic, rarely dimorphic; heterosporous, microspores and megaspores in separate sporangia but within the same strobilus; microsporangia with hundreds of microspores (18-31 (-63) µm diam.); megasporangia with four large megaspores (150-1500 µm diam.); spores tetrahedral-globose.
Discussion:Type: Selaginella spinosa Palisot-Beauvois [=Selaginella selaginoides (Linnaeus) Link, = Lycopodium selaginoides Linnaeus].
Selaginella probably has 600-700 species, mostly of tropical regions. Two major groups are recognized, the isophyllous species, which are mostly of dry regions of Mexico and western United States, and anisophyllous species, which represent by far the largest portion of the genus, these of wet tropical forests.
References: Alston, A. H. G. 1951. A revision of the West Indian species of Selaginella. Bull. Brit. Mus. (Nat. Hist.), Bot. 1: 25-50; Alston, A. H. G. 1955. The heterophyllous Selaginellae of continental North America. Bull. Brit. Mus. (Nat. Hist.), Bot. 1: 222-274; Buck, W. R. 1977. A new species of Selaginella in the S. apoda complex. Canad. J. Bot. 55: 366-371; Gregory, D. & R. Riba. 1979. Selaginellaceae. Flora de Veracruz 6: 1-35; Hellwig, R. L. 1969. Spores of the heterophyllous Selaginellae of Mexico and Central America. Ann. Missouri Bot. Gard. 56:444-464; Tryon, A. 1949. Spores of the genus Selaginella in North America, north of Mexico. Ann. Missouri Bot. Gard. 36: 413-436; Tryon, R. M. 1955. Selaginella rupestris and its allies. Ann. Missouri Bot. Gard. 42: 1-99.