Sporobolus flexuosus

(Thurb. ex Vasey) Rydb.
Common names: Mesa dropseed
Treatment appears in FNA Volume 25. Treatment on page 131.

Plants perennial (rarely appearing annual); cespitose, not rhizomatous, bases not hard and knotty. Culms 30-100(120) cm tall, 1-3 mm thick near the base, erect to decumbent. Sheaths rounded below, smooth or scabridulous, margins some¬times ciliate distally, apices with tufts of hairs, hairs to 4 mm; ligules 0.5-1 mm; blades (2)5-24 cm long, 2-4(6) mm wide, ascending or strongly divergent, flat to involute, glabrous abaxially, scabridulous adaxially, margins scabridulous. Panicles 10-30 cm long, 4-12 cm wide, longer than wide, open, subovate to oblong; rachises drooping or nodding; lower nodes with 1-2 branches; primary branches 1-8(12) cm, flexible, diverging at least 70° from the rachis, often strongly reflexed to 130°, tangled with each other and with branches from adjacent panicles; lower branches no longer than those in the middle, usually included in the uppermost sheath; secondary branches widely spreading, without spikelets on the lower 1/8 – 1/2; pulvini pubescent; pedicels 0.3-3 mm, spreading, scabridulous. Spikelets 1.8-2.5 mm, plumbeous. Glumes unequal, ovate, membranous; lower glumes 0.9-1.5 mm; upper glumes 1.4-2.5 mm, subequal to the florets; lemmas 1.4-2.5 mm, lanceolate to ovate, membranous, glabrous, acute; paleas 1.4-2.4 mm, ovate, membranous; anthers 0.4-0.7 mm, yellow. Fruits 0.6-1 mm, ellipsoid, light brownish to reddish-orange. 2n = 36, 38.


Colo., N.Mex., Tex., Utah, Calif., Kans., Mont., Ariz., Nev.


Sporobolus flexuosus grows on sandy to gravelly slopes, flats, and roadsides in the southwestern United States and northern Mexico. It is associated with desert scrub, pinyon-juniper woodlands, and yellow pine forests. Its elevational range is 800-2100 m.

Selected References


Lower Taxa