Prenanthes alba
prenanthe blanche, white lettuce, white rattlesnake-root
erect, often mottled purple or nearly all purple (often with stout bases, 8–12 mm diam.), proximally glabrous, tomentulose distally.
proximal present at flowering;
petioles narrowly winged (to 18 cm);
blades usually ovate to triangular or cordate, 4–30 × 3–18 cm, thin to coriaceous, bases often hastate, margins usually coarsely dentate or serrate, sometimes deeply 3-lobed or parted, lobes acute, faces glabrous adaxially, pale to whitish and sometimes hirsute abaxially;
distal reduced.
cylindric to campanulate, 13–15 × 3–5 mm.
7–9(–13);
corollas whitish to pale pink, lavender or red, 9–15 mm.
(6–)8(–9), ± purplish or maroon, lanceolate, 10–13 mm, margins scarious, minutely ciliate, apices acute, faces glabrous.
of 5–7, triangular to lanceolate bractlets 1–3 mm, glabrous.
(3–8, in clusters) in paniculiform arrays (densest near apices).
brown or tan, elliptical to linear, 3.5–6 mm;
pappi usually reddish brown, sometimes rusty, rarely yellowish, 6–7 mm.
= 32.
Prenanthes alba
Prenanthes alba is recognized by the purplish stems, relatively large, coarse, ovate or triangular leaves, relatively long, winged petioles, glabrous and often purple phyllaries, and usually reddish brown pappi. The leaves are variable, occasionally deeply 3-lobed. W. L. Milstead (1964) recognized specimens with a pale yellow pappi as “subsp. pallida,” distributed on the east coast in New Jersey, Virginia, and North Carolina. Because pappus color tends to fade somewhat on herbarium specimens, that character is difficult to assess on older specimens. The name was not validly published.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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