Riddell's spike-moss

Selaginella riddellii Van Eseltine, Contr. U.S. Natl. Herb. 20: 162. 1918

Leaves (aerial stems) usually loosely appressed; base often glabrescent. Strobili sometimes with apical vegetative growth, not distinctly larger than subtending stem. Sporophylls usually not abruptly tapering toward apex; apex straight.

Mostly on granite outcrops, granite boulders, or gravelly or sandy soil; 0--200 m; Ala., Ark., Ga., La., Okla., Tex.

The specimens of Selaginella arenicola subsp. riddellii from Texas are more constant in their morphologic characteristics and thus more easily separated from subsp. arenicola .