1. Loeflingia squarrosa Nuttall in J. Torrey and A. Gray, Fl. N. Amer. 1: 174. 1838.
Loeflingia pusilla Curran; L. squarrosa subsp. artemisiarum Barneby & Twisselmann; L. squarrosa var. artemisiarum (Barneby & Twisselmann) Dorn; L. squarrosa subsp. cactorum Barneby & Twisselmann; L. squarrosa subsp. texana (Hooker) Barneby & Twisselmann; L. texana Hooker
Plants 1-12 cm, covered with stalked glands, somewhat fleshy. Stems stiff, usually dichotomously branched at or near base, variously branched or not distally. Leaves usually connate proximally into short, scarious sheath; stipules filamentous to spinose, 0.4-1.5 mm; blade erect to ± recurved, 0.4-5.5 mm, apex blunt to spine-tipped. Inflorescences often secund. Flowers cleistogamous; sepals erect to squarrose, resembling leaves (especially outer pair), usually with 2 filamentous to stiff lateral spurs, 1.8-6.5 mm, becoming hardened, margins often scarious. Capsules 3-angled, 1.5-3.7 mm, 2- 5 times as long as sepals. Seeds 0.4-0.7 mm.
Flowering spring-summer. Sandy, gravelly areas; 0-2100 m; Ariz., Ark., Calif., Kans., Nebr., Nev., Okla., Oreg., Tex., Utah, Wash., Wyo.; Mexico (Sonora).
R. C. Barneby and E. C. Twisselmann (1970) recognized four subspecies of Loeflingia squarrosa, for the most part allopatric. After a reevaluation of the characters used in their key, we feel that those entities are best regarded as geographical races of the species. This is justified largely by both the overlap in expressions of and the lack of correlation of the characters. Barneby and Twisselmann placed major emphasis on habit and stature, including the position of the primary dichotomy of the plant and the location of intermediate monochasial branching subsequent to last branching, if present. In their words, “We have developed an objective formula for describing the permutations of branching, but believe that the intangible quality of habit permits intuitive sorting of material into categories that coincide with comprehensive dispersal patterns.” They used, in addition to habit, the size and stiffness of stipules and sepal spurs, size of sepals and their orientation, size and shape of capsules, and size of seeds to discriminate between subspecies.