Leaves: petioles 5-12(-45) mm; blades 3-5(-9) × 4-5(-8) cm overall, lobes 1-3 mm wide. Peduncles 3-12+ mm. Involucres 2-3+ mm. Phyllaries: outer 5 sparsely strigose or glabrous. Paleae 1-1.5 mm. Functionally staminate florets: corollas 1.5-2 mm. Cypselae 1.4-1.7 mm. 2n = 36.

Flowering Jul-Sep. Disturbed sites (roadsides, washes, etc.), in sandy, gypseous, or calcareous soils; 1000-2000 m; Ariz., N.Mex., Tex.; Mexico (Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Sonora, Zacatecas).

Duration: Annual

Nativity: Native

Lifeform: Forb/Herb

General: Annual with hispid stem, 10-50 cm tall; stems erect, strictly branched.

Leaves: Cauline, mostly alternate, petioles 5-12 mm long, blades 3-5 cm long, 4-5 cm wide, deltate or ovate to lanceolate, 1-3 pinnately lobed, 1-3 mm wide, ultimate margins entire or toothed, faces hispid, usually gland-dotted.

Flowers: Heads disciform, usually in loose panicles, with hemispheric involucres 4-6 mm wide, phyllaries persistent, 10-12 in 2 series, distinct, outer 5 sparsely strigose or glabrous, inner ones scarious to membranous; receptacles hemispheric, the paleae spatulate to linear, membranous, sparsely hairy or glabrate, usually gland dotted; many staminate flowers with whitish corollas, funnelform, 5 lobes, 5-10 pistillate marginal florets with obsolete corollas.

Fruits: Cypselae pyriform, more or less obcompressed, finely striate, glabrous, becoming muricate in age.

Ecology: Found in disturbed sites, on sandy or calcareous soils, to being among rocks; 3,000-5,500 ft (914-1676 m); flowers July-September.

Distribution: se AZ, s NM, sw TX; south to c MEX.

Notes: This species can be non-descript, resembling Ambrosia or Artemesia with small composite heads. Look for heads having both pistillate and staminate flowers, a loose inflorescence with drooping heads; especially distinctive are the pinnately-lobed leaves which do not resemble Ambrosia, and are especially intricately and symmetrically divided as basal rosettes.

Ethnobotany: Unknown

Etymology: Hedosyne comes from Greek, meaning delight, while ambrosiifolia means having leaves like Ambrosia.

Synonyms: Iva ambrosiifolia, Iva ambrosiifolia subsp. lobata

Editor: SBuckley 2010, FSCoburn 2014