Plants 30-80 cm. Stems erect to ascending-erect (not sprawling-scandent). Leaves: petioles 0.5-3 cm; blades deltate-ovate, 1.5-5 × 0.6-2 cm, bases broadly cuneate to subtruncate, margins irreg-ularly crenate-serrate, apices acute to acuminate. Involucres (4-)5-6 mm. Phyllaries: ovate (outer) or elliptic (inner), glabrous, apices usually obtuse to rounded, rarely truncate. Corollas usually pale purple, rarely white. Cypselae 1-1.2(-1.5) mm, glabrous or glabrate.

Flowering Sep-Dec. Rich soils, along streams, rocky slopes; 800-1500 m; Ariz., N.Mex.; Mexico.

Fleischmannia sonorae was reported for Arizona by T. H. Kearney and R. H. Peebles (1960) and F. Shreve and I. L. Wiggins (1964) as Eupatorium pycnocephalum Lessing [= Fleischmannia pycnocephala (Lessing) R. M. King & H. Robinson)]; revised concepts of this species group (B. L. Turner 1996+, vol. 2) place F. pycnocephala as a related species in Mexico and Central America, not reaching northwestward to Arizona.

Duration: Perennial

Nativity: Native

Lifeform: Forb/Herb

General: Perennial herbs, 30-80 cm high; stems erect to ascending.

Leaves: Opposite; on petioles 0.5-3 cm long; blades narrowly triangular, 1.5-5 cm long, by 0.5-2 cm wide, with long-acuminate tips and toothed margins, the teeth more or less rounded at the tips.

Flowers: Flower heads small, discoid, arranged in loose clusters on the tips of flowering stalks which elevate the flowers above the level of the leaves; involucre (ring of bracts wrapped around the flower head) obconic to hemispheric, 2-4 mm diameter, the bracts (phyllaries) 20-30 in 2-4 subequal series, the outer phyllaries ovate and inner phyllaries elliptic, all phyllaries with obtuse to rounded tips; florets all discs, 15-25 per head, the corollas pale purple or rarely white,

Fruits: Achenes 1 mm long, glabrous, with 5 angles; topped with a pappus of long capillary bristles.

Ecology: Found in rich soils along streams and in canyons, from 3,000-5,000 ft (914-1524 m); flowers September-December.

Distribution: AZ and NM; south to n MEX.

Notes: This species was previously reported as Fleischmannia pycnocephala (syn. Eupatorium pycnocephalum) but recent work places that species in Mexico and Central America, not reaching as far north as Arizona. FNA places Arizona material previously reported as F. pycnocephala into F. sonoae. This genus is very similar in appearance to Brickellia. Look to the achenes to help differentiate between them, which are usually 10-sided in Brickellia, (except for Brickelliastrum fendleri), and 5 sided in Fleischmannia.

Ethnobotany: Unknown

Etymology: Fleischmannia horors Gottfried F. Fleischmann (1777-1850), teacher of Schultz-Bipontinus (the botanist who described this genus) at the University of Erlangen; sonorae means from the Sonoran Desert.

Synonyms: Eupatorium sonorae, Eupatorium hymenolepis, Eupatorium schiedeanum var. grosse-dentatum, Eupatorium sinaloense

Editor: LCrumbacher 2011, AHazelton 2016