Shrubs to 100(-200) cm. Leaf blades elliptic to ovate, 10-25(-40+) × 4-15(-20) mm (margins sometimes undulate). Ray florets 0. Disc florets 10-25(-40); corollas 3-4 mm. Cypselae 4-6.5 mm; pappi 2.5-3.5 mm. 2n = 36. Flowering mostly Sep-Nov. Limestone or alkaline or clay soils, gravelly sites, desert scrub; 800-2000+ m; Ariz., N.Mex., Tex.; Mexico. Plants of Flourensia cernua usually have a tarry odor and are often locally co-dominant with Larrea tridentata throughout much of the Chihuahuan Desert.
FNA 2006, Powell 1998
Common Name: American tarwort Duration: Perennial Nativity: Native Lifeform: Shrub General: Shrub 1-2 m tall, densely leafy. Leaves: Alternate, blades elliptic to ovate, 10-25 mm by 4-15 mm, pointed, margins sometimes undulate. Flowers: Heads 1 cm long, nodding, sessile or on short stalks, no ray flowers, disk flowers perfect 10-25, corollas 3-4 mm, yellow; involucre bellshaped, strongly overlapping phyllaries, in 3 series; glutinous herbage, tips spreading, chaffy receptacle. Fruits: Cypselae flattened, hairy, 4-6.5 mm, pappus of unequal awns, 2.5-3.5 mm, these fringed. Ecology: Found in desert flats, often co-dominant with creosote from 2,500-6,500 ft (762-1981 m); flowers September-December. Distribution: se AZ, s NM, sw TX; south to c MEX. Notes: Often found co-dominant with Larrea tridentata throughout the Chihuahuan desert. Distinguished by being a medium-sized, much-branched shrub with sticky-resinous foliage; oval to elliptic leaves; and small nodding heads with herbaceous pappus, all disk flowers and a pappus of two awns. Ethnobotany: Used as a treatment for indigestion and other stomach ailments. Etymology: Flourensia is named for Marie-Jean-Pierre Flourens (1794-1867) a French physiologist, while cernua means drooping or nodding. Synonyms: None Editor: SBuckley 2010, FSCoburn 2015