Shrubs, 50-200 cm (freely branched, broomlike) . Stems erect, fastigiate, striate-angular, green, glabrous, resinous. Leaves cauline (proximal withering and sparse by flowering); sessile; blades (1-nerved) broadly oblanceolate to obovate or spatulate, 10-35 × 5-15 mm (thick, firm), bases attenuate , margins entire or irregularly serrate (teeth 1-4, distal leaves entire), apices obtuse to acute, faces glabrous, gland-dotted, resinous. Heads (sessile or short-pedunculate on lateral branches) in crowded paniculiform arrays. Involucres funnelform to campanulate; staminate 3-5 mm, pistillate 3-5 mm. Phyllaries ovate to linear-lanceolate, 1-5 mm, margins scarious, erose, medians green, apices rounded to acute, glabrous, gland-dotted, resinous. Staminate florets 24-33; corollas 2-3.5 mm. Pistillate florets 15-30; corollas 1.6-2.7 mm. Cypselae 1-2 mm, prominently 10-nerved, glabrous; pappi 1.7-3.1 mm. 2n = 18. Flowering Jul-Oct. Gravelly or sandy streambeds, dry washes, grasslands; 100-1800 m; Ariz., Calif., Nev., Utah; Mexico (Baja California, Sonora). Baccharis sergiloides is recognized by its fastigiate, broomlike habit, and large obovate leaves that often wither before flowering. It differs from B. sarothroides in its larger leaves, more or less sessile and lateral heads, and smaller florets and fruits.
FNA 2006, Benson and Darrow 1981, Kearny and Peebles 1979
Common Name: desert baccharis Duration: Perennial Nativity: Native Lifeform: Shrub Wetland Status: FACU General: Dioecious, broomlike shrub, 50-200 cm tall; stems numerous, erect, green, strongly striate-angular with 3-4 longitudinal ridges, glabrous, resinous. Leaves: Alternate and sessile; blades broadly oblanceolate to obovate or spatulate, 1-4 cm long by 0.5-1.5 cm wide, the bases attenuate, apices obtuse to acute, margins entire or irregularly serrate, surfaces glabrous, gland-dotted, resinous. Leaves usually wither before flowering. Flowers: Flower heads unisexual, discoid, sessile or short pedunculate and arranged in crowded panicles; involucre (the ring of bracts surrounding the flower head) funnel or bell shaped, 3-5 mm tall, the bracts (phyllaries) ovate to linear-lanceolate, resinous, green in the middle, with scarious (dry, membranous) margins; florets all discs, 24-33 (staminate) or 15-30 (pistillate) per head, the corollas 2-3 mm, pistillate corollas white and the staminate corollas white to pale yellow. Fruits: Achenes 1-2 mm, prominently 10-nerved, glabrous, with pappus of 2-3 mm minutely barbellate bristles. Ecology: Found in sandy washes and in canyons from 2,000-5,000 ft (610-1524 m); flowers July-October. Distribution: CA, NV, UT, AZ; south to n MEX (Baja California, Sonora) Notes: Baccharis is a genus of shrubs with gland-dotted leaves; unisexual, discoid flower heads, with male and female flower heads on separate plants; tufts of bristles (pappus) attached to the tops of the seeds; and phyllaries (bracts on the flowering heads) that are herbaceous in the middle and dry and papery on the edges. B. sergiloides is recognized by its broomlike growth form and large obovate leaves which wither before flowering. Looks similar to B. sarothroides but that species has smaller leaves, about 1 cm long. When attempting to identify a Baccharis, it is recommended to try and collect material from both male and female plants. Ethnobotany: Unknown, but other species in the genus have many uses. Etymology: Baccharis is named for Bacchus, the god of wine, while sergiloides is thought to come from French serge, for silken. Synonyms: None Editor: SBuckley 2010, AHazelton 2015