Shrubs, 30-400 cm (stems cluster-ed). Stems spreading to ascending, green to tan, simple proximally, sparingly branched distally, striate-angled, glabrous or minutely hairy, resinous and ± resin-varnished. Leaves present at flowering (abundant, well developed); sessile or petiolate; blades lanceolate-elliptic, slightly falcate (willowlike), 30-150 × 3-20 mm, bases attenuate , margins usually finely serrate from bases to apices, sometimes entire, apices acute to acuminate, faces glabrous, gland-dotted, ± resinous. Heads in terminal, compound corymbiform arrays (often involving distal branches). Involucres hemispheric; staminate 3-6 mm, pistillate involucres 3-6 mm. Phyllaries ovate to lanceolate, 2-4 mm, margins scarious, erose or irregularly dentate, midribs distinct, medians green or reddish, apices (greenish or brownish purple) obtuse to acuminate (pale and dry, glabrous). Staminate florets (10-)17-48; corollas 4-6 mm. Pistillate florets 50-150; corollas 2-3.5 mm. Cypselae 0.8-1.5 mm, 5-nerved, glabrous; pappi 3-6 mm. 2n = 18, 36. Flowering (Jan-)Mar-Oct. Stream banks, dry washes, sandy flood plains, riparian woodlands, disturbed sites, ditches; 30-2400 m; Ariz., Calif., Colo., Nev., N.Mex., Tex., Utah; Mexico; South America. Baccharis salicifolia is part of a complex that extends through the southwestern United States, Mexico, Central America, and South America to Argentina and Chile (J. Cuatrecasas 1968). It is recognized by the narrowly lanceolate, willowlike, finely serrate leaves with acute or acuminate apices, smallish heads in dense clusters, reddish phyllaries, and 5-nerved cypselae. By tagging and measuring individual plants throughout the year, D. H. Wilken (1972) demonstrated that B. salicifolia has distinct seasonal forms. The North American plants were once known as B. glutinosa or B. viminea, which were differentiated from each other by differences in woodiness, leaf size and serration, and flowering time.

Plant: Dioecious shrub to 3 m, glabrous to minutely puberulent, often ± sticky; stems: main stems generally 1-few; branches few-many, short, spreading or ascending Leaves: leaves alternate, 4-8 cm, usually toothed with 1 prominent midvein, petioles winged; INFLORESCENCE: primary inflorescence a head, each resembling a flower; heads in a pyramid-shaped to rounded panicle; involucre hemispheric, of staminate heads (3)4-6 mm, of pistillate heads 3-6 mm; phyllaries in 4-5 series, awl-shaped to lanceolate, irregularly toothed, generally tinged red, glabrous (except ciliate margins), tip obtuse to long-tapered; receptacle flat to convex, smooth, glabrous to tomentose, chaff 0 Flowers: Staminate flowers (10)17-48; corollas (3)4-6 mm, pappus (3)3.6-5 mm; Pistillate flowers 50-150; corollas 2.2-3.5 mm Fruit: achenes, 0.8-1.3 mm, cylindric, glabrous; ribs 5; pappus 4.2-6 mm Misc: Canyon bottoms, moist streamsides, irrigation ditches, often forming thickets; < 1250 m.; Feb-Dec Notes: dioecious shrubs References: Kearny & Peebles; Arizona Flora, ASU specimans