Thymophylla pentachaeta var. belenidium (DC.) J. L. Strother

Thymophylla gracilis Rydberg, sp. nov
Hymenatherum Hartwegii A. Gray, PI. Wright. 1: 117, in part. 1852.
Thymophylla Hartwegii Wooton & Standley, Contr. U. S. Nat. Herb. 16: 191, in part. 1913.
A puberulent perennial, with a slender, suffruticose base; stems 1-2 dm. long, minutely puberulent or glabrate, diffusely branched; leaves mostly opposite, 2-4 cm. long, pinnatifid, with 3-7 slender, filiform, approximate, spinulose-tipped, puberulent divisions; peduncles 4-6 cm. long, slender; involucre turbinate-campanulate, 4-5 mm. high, 5-6 mm. broad, naked, glabrous, except the ciliate margins of the outer series of bracts; bracts in two series of about 8 bracts each, united high up; inner bracts oblong, with triangular erose tips and 3-5 glands; outer bracts linear, with the ciliate free margins decurrent to near the base, their glands 5-7; ligules yellow, 3-4 mm. long, fully 1 mm. broad; disk-corollas about 3 mm. long; achenes 2.5 mm. long, glabrous; pappus distinctly double; inner 5 squamellae 2.5 mm. long, awned, the outer 5 scarcely 0.5 mm. long, spatulate-oblong.
Type collected at Barstow, Texas, July, 1901, David Griffiths 622 (herb. N. Y. Bot. Gard.). Distribution: Texas to Arizona and Lower California.

Thymophylla thurberi (A. Gray) Wooton & Standley, Contr U. S. Xat. Herb. 16: 191. 1913.
Hymenatherum tenui folium var. A. Gray, PI. Wright. 2: 93. 1853. Hymenatherum Thurberi A. Gray, Proc. Am. Acad. 19: 41. 1883. Dyssodia cupulala A. Nelson, Bot. Gaz. 47: 435. 1909. Dyssodia Thurberi B. L. Robinson, Proc. Am. Acad. 49: 508. 1913.
A pubescent perennial, suffruticose at the base; stems 1-2 dm. high, diffusely branched, finely short-pilose; leaves mostly opposite, sessile, 1.5-3 cm. long, pinnatifid into 5-7 narrowly filiform spinulose-tipped divisions, short-pilose; peduncles slender, 4-S cm. long; involucre turbinate-campanulate, 4-5 mm. high, 5-6 mm. broad, naked or with 1-3 minute subulate accessory bracts; principal bracts in two series, united high up, the inner broader, with triangular tips and 3-5 glands near the apex, the outer linear, acute, with the ciliate free margins decurrent nearly to the base, their glands 5-9, in two rows; ligules 3 mm. long, 1-1.5 mm. wide; diskcorollas 2.5 mm. long; tube very short; throat trumpet-shaped; lobes ovate; achenes 2-3 mm. long, hispidulous on the angles; pappus 2-3 mm. long, of 10 lanceolate awntipped squamellae, the inner 5 usually 3-awned, the outer ones with a single short awn or awn-tip.
Type locality: "Border of western Texas and Mexico near El Paso" [but the type was collected within Chihuahua].
Distribution: Texas to Nevada, Durango, and Coahuila.