Perennials, 4-35 cm; rhizomes shallow, spreading (forming vegetative rosettes), roots fibrous. Stems 6-12+, erect or stiffly ascending, slender, sparingly branched distally, glabrous. Leaves basal and cauline; sessile, clasping; basal blades linear-oblanceolate, abruptly reduced distally, 10-40 × 1.5-3 mm (succulent), margins entire with 8-20 cilia per side (cilia 0.4-1.5 mm), apices acute (bristly-tipped), faces glabrous, glaucous. Heads borne singly (terminal), often in corymbiform arrays. Involucres broadly turbinate, 7-10 × 5-8 mm (fresh). Phyllaries in 4-6 series, appressed, oblong to oblanceolate or obovate, 1-4 mm, bases whitish, midnerves dark, margins laciniate-ciliate, apices green, broadly acute or short-acuminate, faces glabrous. Ray florets 8-12+; laminae blue, 8-10 mm, coiling after flowering. Disc florets 12-18+; corollas yellow or sometimes purple-tinged, 4.5-5.5 mm. Cypselae narrowly oblong-oblanceolate, 1.7-2.4 mm, nerves 8-11 per face, faces sericeous; pappi tawny, setose; ray 1.5-2 mm; disc 3.5-4 mm. 2n = 10. Flowering Sep-Oct. Limestone areas, mountains; 1500-2200 m; N.Mex., Tex.; Mexico (Chihuahua). Arida blepharophylla is recognized by its perennial habit and leaves with long cilia on the margins. The perennial habit and branching caudex are similar to Xanthisma sect. Blepharodon. Within Arida, A. blepharophylla appears to be closely related to A. riparia, and the two species probably hybridize.
The type collection was made by Charles Wright in 1851 in present-day New Mexico and originally named Aster blepharophyllus. The species was not rediscovered until 1971 in Chihuahua, Mexico, in an area of gypsic hot springs. When transferred to Machaeranthera, it was given the name M. gypsitherma because the original epithet is blocked in that genus by the earlier, heterotypic M. blephariphylla (A. Gray) Shinners.
This project made possible by National Science Foundation Award 1410069