Baccharis bigelovii
Baccharis pteronioides
Bigelow's false willow
yerba de pasmo
erect to ascending, slender, striate-angled, glabrous, resinous.
erect, terete, brittle, slightly striate, scabrous, stipitate-glandular, papillose-roughened.
present at flowering; short-petiolate;
blades (1- or obscurely 3-nerved) obovate to oblanceolate, 20–35 × 3–15 mm, distally reduced and narrowed, bases cuneate, margins irregularly incised to coarsely serrate or 2-serrate, faces glabrous, gland-dotted, resinous.
cauline (proximal withering before flowering, distal crowded in gascicles);
sessile;
blades linear to lanceolate or spatulate, 5–25 × 1–6 mm (stiff, coriaceous to fleshy), bases attenuate, margins sharply serrate (teeth 1–5 pairs, distal leaves often entire), faces glabrous, gland-dotted, resinous.
campanulate;
staminate 4–5 mm, pistillate 4–5 mm.
campanulate;
staminate 4–5 mm, pistillate 5–6(–7) mm.
25–30;
corollas 2–2.6 mm.
15–20;
corollas 4–5 mm.
15–20;
corollas 3.5–4 mm.
15–20;
corollas 4–5 mm.
lanceolate, 1–4 mm, margins scarious, medians green, apices acute, erose.
ovate to lanceolate, 1–5 mm, margins scarious, medians green, apices acute to acuminate, glabrous.
(20–50) in corymbiform arrays.
(10–20+ on densely leafy lateral branchlets) in spreading racemiform arrays.
1.5–2.2 mm, 5-nerved, glabrous;
pappi 3–4.5 mm.
1.8–3 mm, 8–10-nerved, minutely papillose-glandular;
pappi 8–10 mm (bristles rigid).
Baccharis bigelovii
Baccharis pteronioides
Baccharis bigelovii occurs in the general Chihuahuan Desert region in the Davis Mountains of West Texas, and in the Chiricahua and Huachuca mountains of Arizona. It is recognized by the relatively short stature, obovate, coarsely and irregularly serrate leaves, erose-ciliate phyllaries, and 5-nerved cypselae. It is similar to B. thesioides, which differs mainly by having narrower, more oblong leaves with more evenly serrate margins and spinulose teeth. Further investigation may show these two taxa to be different geographic expressions of a single species centered in Mexico.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Baccharis pteronioides is characterized by its shrubby stiff habit, rough gray bark, branches that are evenly spaced and often at 45° angles, fascicles of narrow sessile leaves, and heads in racemiform arrays on short leafy branches. The Mexican common name yerba de pasmo refers to an infusion of the leaves used to treat chills (pasmo) and sores; the plants are also said to be poisonous to cattle and sheep.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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