Polygala lindheimeri A. Gray var. parvifolia Wheelock, Mem. Torrey Bot. Club 2: 143. 1891; P. tweedyi Britton ex Wheelock

Stems usually pubescent, rarely glabrous, hairs usually closely incurved, occasionally loosely so, or rarely irregularly spreading, 0.07–0.15 mm. Leaf blades lanceolate, linear, scalelike to elliptic, ovate, or obovate, 3–41 × 0.5–10 mm, venation usually not prominently reticulate, except midvein abaxially, occasionally reticulate, surfaces with pubescence similar to stems or glabrous. Keel sacs glabrous or, rarely, with incurved hairs in distal 1/2. 2n = 18.

Flowering early spring–fall (year-round). Rocky or clay soils of limestone or igneous origin, infrequently on gypseous substrates, occasionally in rock crevices of open slopes, ridge tops, canyons, savannas, desert grasslands, oak-pinyon woodlands, chaparral; 300–2400 m; Ariz., N.Mex., Okla., Tex.; Mexico (Chihuahua, Coahuila, Nuevo León, Zacatecas).

As discussed by T. L. Wendt (1978), var. parvifolia, the most widespread and variable variety, intergrades fairly extensively with the others, especially in the southern and western portions of its range, where it is relatively common to find morphological intermediates. Despite var. parvifolia having been treated as a distinct species by other workers, for example, S. F. Blake (1916, 1924), Wendt made a compelling case correlating morphology with geography, ecology, and karyology, for nomenclatural recognition at varietal rank.