Perennials, (20-)40-80(-140) cm (caudices branched, fibrous-rooted). Herbage glabrous or glabrate. Stems single or loosely clustered. Leaves ± evenly distributed (proximal often withering before flowering); petiolate or sessile; blades ovate or lanceolate to narrowly lanceolate, (3-)6-12(-20) × (1-)1.5-5(-7) cm, bases tapered, margins usually pinnate to lacerate, sometimes dentate. Heads 10-60+ in compound corymbiform arrays. Calyculi of 3-5+ (prominent or inconspicuous) bractlets (lengths to 3 / 4 phyllaries). Phyllaries (± 8) ± 13, 3-8+ mm, tips green or black. Ray florets ± 8; corolla laminae 5-10 mm. Cypselae usually glabrous, sometimes hirtellous. 2n = 38, 40, 44.
Varieties of Senecio eremophilus are distinguished by head size and distribution. Varieties eremophilus and macdougalii are notably different; var. kingii is intermediate in both morphology and distribution.
Duration: Perennial Nativity: Native Lifeform: Subshrub General: Perennial, 30-100 cm tall; stems 1 to several, loosely clustered, often reddish or purplish; herbage glabrous or nearly so; caudex branched; fibrous-rooted. Leaves: Cauline (the lower blades often withered by flowering), alternate, ovate or lanceolate in outline, 2-15 cm long, 1-5 cm wide, margins pinnately lobed, cleft irregularly, or toothed; blades petiolate or sessile. Flowers: Heads 3-12, seldom as many as 25, arranged in raceme-like or panicle-like arrays, nodding (especially when young); bractlets subtending the involucre 4-10, linear; involucre 8-10 mm long, 10-15 mm wide; phyllaries mostly 13 or 21, in 2 series, tips green, margins membranous; disk flowers only, numerous, yellow; flowers July- September. Fruits: Achene, glabrous to minutely hairy along the ribs; pappus of 30-80 white to straw-colored bristles. Ecology: Meadows, streamsides, mountain slopes, coniferous forests, roadsides, disturbed habitats; 1900-3700 m (6500-12000 ft); Apache, Cochise, Coconino, Gila, Graham, Greenlee, Mohave, Navajo, Pima, Santa Cruz, and Yavapai counties; southwestern Canada, north-ce Notes: Two varieties occur within our region and are distinguished as follows: var. kingii has conspicuous bractlets subtending the involucre, involucres are 6-8 mm wide, with black tips on the phyllaries, and the ligules of ray flowers are 5-8 mm long; var. macdougalli has inconspicuous bractlets subtending the involucre, involucres are 4-5 mm wide, usually with black tips on the phyllaries, and the ligules of the ray flowers are smaller, 5-6 mm long. Senecio vulgaris (old-man-in-the- Spring) is an introduced annual, mostly 20-50 cm tall, with glabrous to sparsely tomentose herbage (particularly when young); leaves are ovate to oblanceolate, 2-10 cm long, 0.5-2 cm wide, the margins dentate or minutely lobed; heads are numerous, arranged in corymb-like arrays; bracts subtending the involucre are black-tipped; ray flowers are absent, disk flowers are numerous, yellow. It typically occurs in disturbed sites. Editor: Springer et al. 2008