Annuals, 5-60 cm. Stems 1-5+, ± erect, branched distally, sparsely leafy, glabrous. Cauline leaves: proximal obovate, pinnately lobed (lobes 3-5+ pairs, triangular to oblong or linear), not fleshy, ultimate margins entire or dentate, faces glabrous; distal reduced (usually with 2 lobes near bases). Calyculi of 5-8+, ovate to lanceolate bractlets, hyaline margins 0.05-0.2 mm. Involucres ± campanulate, 7-10 × 3-6 mm. Phyllaries 16-20+ in 2-3 series, lanceolate to lance-linear, hyaline margins 0.05-0.1 mm wide, faces glabrous. Receptacles not bristly. Florets 19-70; corollas usually yellow, sometimes white, 6-7 mm; outer ligules exserted 1-2 mm. Cypselae ± cylindro-fusiform, 1.7-2.3 mm, ribs extending to ca. 0.1-0.2 mm short of apices (minutely hirtellous or muriculate), ± equal (distal 0.1-0.2 mm of cypselae smooth); pappi persistent, of 8-15+, needlelike teeth plus 1(-2) bristles. Pollen 70-100% 4-porate. 2n = 28.

Flowering Mar-Jun. Gravelly soils beneath shrubs, along ditches, near streams, in sagebrush steppes, creosote bush scrublands; 300-1300 m; Ariz., Calif., Nev., N.Mex.; Mexico (Sonora).

Malacothrix stebbinsii grows in the Mojave Desert (Borrego area, California) and the Sonoran Desert (Santa Catalina, Mazatzal, Baboquivari, and Santa Rita mountains, and elsewhere in Arizona).

Duration: Annual

Nativity: Native

Lifeform: Forb/Herb

General: Herbaceous annuals, to 50 cm tall, stems 1-5, slender, usually branching from the base, glabrous, leafy, with milky sap.

Leaves: Mostly basal, to 10 cm long, proximal oblanceolate to lance-linear, sometimes pinnately lobed, the lobes up to 3 mm wide, not fleshy, ultimate margins usually dentate, faces glabrous, becoming alternate and reduced apically, the margins 2-4-dentate near the bases or entire.

Flowers: Heads small, radiate, rays yellow, inconspicuous, the outer rays exserted 1-2 mm, receptacles not chaffy, involucres 6-7 mm high, small bracts around the calyx, of 5-12, lance-deltate to lanceolate bractlets, phyllaries subequal, 8-15 or more in 2 or more series, these lance-linear to linear, the abaxial faces glabrous, inflorescences with many heads borne in terminal panicles.

Fruits: Achenes oblong-linear, truncate, ribbed, crowned with a ring of minute teeth. Pappus of soft bristles, 1-2 of them stiffer and persistent, the remainder deciduous more or less in a ring.

Ecology: Found along streams, in cleared areas, burns, slides, chaparral, and creosote bush shrub from 2,500-4,500 ft (762-1372 m); flowering March-June.

Distribution: Arizona, California, Nevada, New Mexico; Mexico.

Ethnobotany: Unknown

Etymology: Malacothrix is from malakos, soft and thrix, hair, while stebbinsii is named for George Ledyard Stebbins Jr. (1906-2000) an American geneticist and evolutionary biologist.

Synonyms: Malacothrix clevelandii var. stebbinsii

Editor: LCrumbacher 2011