Subshrubs, 20-140 cm. Stems glabrous or minutely hispidulous. Leaves: basal and proximal absent at flowering; cauline blades 1-nerved, linear or filiform to narrowly oblanceolate or lanceolate, 0.5-2.2(-4) mm wide, little reduced distally. Heads (2-6, sessile to subsessile, in compact glomerules) in flat-topped arrays. Involucres cylindric, 1-1.5 mm diam. Phyllary apices flat. Ray florets 1(-2; each enclosed by conduplicate inner phyllary); corollas yellow, (1.5-)2-3.5 mm. Disc florets 1, sometimes 2 (functionally staminate; corollas broadly obdeltate-funnelform, throats widely flaring, lobes ¹ / 3 corolla lengths, recurved-coiling). Cypselae 1-1.8(-2.5) mm, faces densely strigoso-sericeous; pappi (rays, readily falling) of 1 series of narrowly lanceolate-oblong scales). 2n = 8, 16, 24, 32.

Flowering (Jun-)Jul-Dec(-Feb). Grasslands, chaparral, oak or oak-pine woodlands, usually over gravelly or rocky limestone or gypsum substrates, dunes; 800-2500 m; Ariz., Calif., Colo., Nev., N.Mex., Tex., Utah; Mexico (Baja California, Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Sonora, Tamaulipas, Veracruz, Zacatecas).

Gutierrezia microcephala is recognized by its perennial habit and its small, tightly clustered heads, each with 4-8 phyllaries and 1(-2) ray and disc florets. Each ray floret is enclosed by a conduplicate inner phyllary. Forms of G. sarothrae with few florets in each head can be distinguished by their bisexual and fertile disc florets and tubular-funnelform disc corollas.

Common Name: threadleaf snakeweed

Duration: Perennial

Nativity: Native

Lifeform: Subshrub

General: Native perennial subshrub from a woody base; stems more-or-less herbaceous (though generally more woody than G. sarothrae), branched, 30-100 cm tall, dying back somewhat in winter.

Leaves: Alternate; primary leaves linear to linear-oblanceolate, 2-5 cm long, 2-4 mm wide, often deciduous by flowering; secondary leaves in fascicles in axils of primary ones, shorter and narrower.

Flowers: Heads numerous, usually in clusters of 3-several at tips of branchlets; inflorescence usually dry and persistent throughout non-growing season above green living parts; involucres 3-4 mm high; disk 1-1.5 mm wide, yellow; rays 1-2, 3-4 mm long; phyllaries whitish or yellowish with a green tip.

Fruits: Cypselae 2-3 mm long, hairy, with a pappus 0.5-1 mm long.

Ecology: Dry, open, often disturbed/overgrazed areas from 1,000-7,000 ft (305-2135 m); flowers June-October.

Distribution: SW US and CA, NV, UT, CO, NM and TX; south to c MEX.

Notes: Gutierrezia in our region are mostly low-growing shrubs with resinous, linear leaves lacking translucent oil glands and small heads with very few yellow ray and disk flowers, a pappus of erect bracts (paleae) and no chaff (bracts from the involucre subtending florets). This species very similar to G. sarothrae, except for the somewhat more woody stems and smaller heads with usually 1 ray flower (3-9 in sarothrae), 1 disk flower (3-9 in sarothrae) and up to 6 phyllaries.

Ethnobotany: Hopi use for gastric problems, as decorations for paaho (prayer sticks), and in roasting sweet corn. Navajo use it to heal cuts and bites. The ashes are rubbed on the forehead to cure a headache, nervousness, or fever. The flowers make a yellow dye.

Etymology: Gutierrezia is named for Pedro Gutierrez (Rodriguez), a 19th century Spanish noblemen and botanist, while microcephala means small head.

Synonyms: Xanthocephalum microcephalum

Editor: SBuckley 2010, FSCoburn 2015