Torrey & A. Gray, Fl. N. Amer. 2: 258. 1842.
Willow-baccharis, Great Plains false willow
Nuttall, Trans. Amer. Philos. Soc., n. s. 7: 337. 1840, not (Ruiz & Pavón) Persoon 1807;
100—300 cm (much branched).
ascending, striate-angled, glabrous, smooth or minutely roughened, resinous.
present at flowering (numerous and well developed); short-petiolate; blades (at least broader distinctly 3-nerved) oblong to oblanceolate, 25—70 × 5—10(—20) mm, bases tapering attenuate, margins usually serrate distally (teeth 1—3, coarse irregular, ca. 5 mm apart), sometimes entire, apices acute or obtuse, faces finely gland-dotted.
(100—200+, short-pedunculate or sessile) in (large, crowded, leafy) paniculiform arrays.
narrowly obconic to campanulate; staminate 4—7 mm, pistillate 5—9 mm.
lanceolate , 2—6 mm, margins scarious, medians green or reddish, apices greenish or purplish, often erose-ciliate, faces glabrous, gland-dotted, resinous
. Staminate florets
20—25; corollas 3—5 mm.
25—30; corollas 3—4 mm.
1.2—2 mm, irregularly 8—10-nerved, glabrous;
8—12 mm (elongating in fruit).
Flowering May—Nov. Stream banks, alkaline meadows, roadsides; 300—1600 m; Ariz., Calif., Colo., Kans., Nev., N.Mex., Okla., Tex., Utah; Mexico (Baja California, Chihuahua, Coahuila, Durango, Sonora).
is recognized by its narrow, gland-dotted leaves with 1—3 irregular teeth on the distal half, heads in loose leafy arrays, campanulate involucres, and cypselae with 8—10 ribs.
The recognition of
as a separate species in other floras has been based on its wider, glabrous, eglandular leaves, more cylindric pistillate involucres, and dense whitish pappi. It was said to occur both west of the Rocky Mountains and in western Texas. In our study, expressions of the characters used to distinguish
from other species were found to be inconsistent and inadequate to warrant recognition as a distinct species. There appears to be a complex of up to four species—
emoryi, salicina, neglecta
—that intergrade from west to east. Characteristics progress from broader leaves and larger heads (
) to narrow leaves with small heads (
). The delimitation of taxa within this complex merits further investigation.