Plants on rock or terrestrial, forming compact clumps or mounds. Stems radially symmetric, underground (rhizomatous) and aerial, not readily fragmenting, irregularly forked; rhizomatous and aerial stems often with 1 branch arrested, budlike, tips straight; aerial stems erect or ascending to decumbent, budlike branches throughout. Rhizophores borne on upperside of stems, restricted to rhizomatous stems or to lowermost base of aerial stems, 0.2--0.3 mm diam. Leaves dimorphic, in alternate pseudowhorls of 5. Rhizomatous stem leaves strongly appressed, overlapping, scalelike. Aerial stem leaves tightly appressed, ascending, green, narrowly lanceolate to linear-lanceolate, (2.5--)3--4.5 X 0.4--0.7 mm; abaxial ridges inconspicuous or more visible from apex to middle of leaf; base cuneate, decurrent, glabrous; margins short-ciliate to denticulate or entire, cilia transparent, spreading, 0.02--0.06(--0.08) mm; apex keeled (more so in dry leaves); bristle transparent or yellowish to brownish near base, puberulent, twisted, persistent or falling off early, 1.2--1.7 mm (1/3--1/2 length of leaves). Strobili solitary, 4--6 mm; sporophylls ovate-lanceolate to lanceolate, abaxial ridges obvious, base glabrous, margins denticulate, apex keeled, long-bristled, bristle twisted.

soil, less often in shaded sites; 600--1500 m; Ga., N.C., S.C., Tenn.

Selaginella tortipila , a very distinct species, is probably without close relatives in the flora but may be distantly related to S . rupestris . The two irregularly forked branches are particularly unusual: the larger one forms the strobilus while the smaller becomes arrested and forms either a budlike branch or grows and divides again to form a vegetative shoot.