Baccharis thesioides
Baccharis havardii
Arizona baccharis, Mogollon baccharis
Havard's false willow
erect to ascending, slender, striate-angled, glabrous, scarcely resinous.
erect (green to tan), slender, striate-angled, glabrous, resinous.
usually present at flowering;
sessile;
blades (1-nerved) linear-oblanceolate to narrowly oblong, 20–40(–80) × 4–8 mm, bases cuneate, margins evenly serrate (teeth spinulose, apices acute, faces finely gland-dotted, not resinous).
present at flowering; short-petiolate;
blades (1-nerved) narrowly spatulate to linear, 20–40 × 2–3 mm, reduced to bracts distally, bases attenuate, margins entire or toothed (teeth to 2 mm), faces glabrous, gland-dotted, resinous.
campanulate; staminate 3–6 mm, pistillate 3–6 mm.
cylindro-campanulate; staminate 3 mm, pistillate 4–4.5 mm.
30;
corollas 2.2–3 mm.
15–20;
corollas 3 mm.
20–30;
corollas 3 mm.
12–15;
corollas 3–4 mm.
lanceolate, 1–5 mm, margins scarious, erose-ciliate, medians green, apices acute or obtuse (erose, abaxial faces glabrous).
lanceolate, 1–4 mm, margins scarious, medians green or brownish, apices obtuse to acuminate (thickened, slightly erose and ciliate).
(10–50+) in terminal, compact, rounded paniculiform arrays.
in broad paniculiform arrays.
1.5–2.2 mm, 5-nerved, glabrous;
pappi 4–6 mm.
2–2.5 mm, 5-nerved, glabrous;
pappi 4 mm.
Baccharis thesioides
Baccharis havardii
Baccharis thesioides is recognized by its erect stems, narrow, oblong, evenly serrate leaves with finely spinulose teeth, heads in relatively small rounded arrays, and 5-ribbed cypselae with short pappi. It is sometimes confused with B. bigelovii, which has broader and irregularly serrate leaves. The two taxa may belong to the same species complex centered in Mexico.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Found mainly in the Chisos and Davis Mountains of West Texas, Baccharis havardii is distinguished by its short bushy habit, narrow leaves with elongate teeth, and 5-nerved cypselae. G. L. Nesom (pers. comm.) suggested that it is weakly defined and further investigation may demonstrate it should be included in the Mexican species B. sulcata de Candolle (which name would have priority over B. havardii).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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