Draba asprella

Draba asprella is a perennial herb that grows in small, low clumps. At its base, the plant has a thickened stem base called a caudex with multiple branches. Around each caudex branch, there is a rosette of obovate leaves, 0.8–4.5 cm long and 2–12 mm wide, which are sessile or borne on very short petioles. The leaf margins are typically smooth but may also be minutely toothed. Small hairs called trichomes cover both the upper and lower faces of the leaves, each 0.2–1.9 mm long; these hairs may be simple or branched, with 2–4 rays. The inflorescence is borne on an unbranched, leafless stem (4–)6–15(–27) cm in length, also covered in simple or 2–4-rayed trichomes. The flowers, typically 30–75 in number, are arranged in a raceme and are not subtended by bracts. Each flower is yellow, with ovate sepals 1.8–3.5 mm long. The fruit are ovate, hairy, and nearly flat but with inflated bases. The two varieties of Draba asprella are distinguished by the structure of the hairs on the fruit: D. asprella var. asprella has simple and 2-rayed trichomes 0.3–1 mm long whereas D. asprella var. stelligera has 2–4-rayed trichomes 0.1–0.2 mm long.

Draba asprella is endemic to Arizona, where it grows in Apache, Cochise, Coconino, Graham, and Pinal counties, where it grows in shaded sites in pine forests. Its elevational range is 1500- 2400 m. The two varieties are found in different soil types: D. asprella var. asprella grows in soil with igneous rocks, and D. asprella var. stelligera grows in limestone and sandstone outcrops.