Prenanthes serpentaria
Prenanthes autumnalis
butterweed, cankerweed, gall-of-the-earth, lion's-foot
slender rattlesnakeroot
erect, green to reddish or purple mottled, proximally glabrous, distally sparsely tomentulose.
1–5, erect, mostly green with mottled purple, slender, simple, glabrous.
proximal often withered by flowering; petiolate (petioles 1–10 cm, often with pair of lobes);
blades deltate to ovate or elliptic, 5–20 × 4–10 cm, coriaceous, margins usually deeply, pinnately 3–5-lobed, lobes and sinuses large and ± rounded, sometimes deeply cleft to base or palmately divided, apices acute or obtuse, ultimate margins entire or dentate, faces glabrous or finely tomentose on veins;
cauline sessile or petiolate;
distal reduced in size and lobing, often entire.
proximal present at flowering; petiolate (petioles winged);
blades oblong to linear, 7–18 × 0.5–6 cm, coriaceous, bases attenuate, margins deeply pinnately lobed or divided, lobes narrow and at right angles, apices acute to acuminate, faces glabrous or slightly glabrate along veins; distally sessile and much reduced.
cylindric (often attenuate basally to bracteate peduncles), 12–15 × 4–5 mm.
cylindro-campanulate, 10–13 × 3–4 mm.
(8–)10–14(–19);
corollas usually yellow to pale yellow, 9–15 mm.
8–10;
corollas usually pinkish, sometimes lavender or white, 11–17 mm.
(7–)8–(10), green or often purple, narrowly lanceolate to elliptic, 10–13 mm, sparsely hispid to appressed, coarsely setose, often reduced to single coarse, appressed seta (setae green or tan).
7–8, pink or purple, linear to elliptic, 8–13 mm, glabrous.
of 8–10, green to purple, triangular to subulate bractlets 1–4 mm, often tomentulose to setose.
of 6–8, green to purple, triangular to subulate bractlets 1–4 mm.
(6–12 in nodding clusters) in broad, paniculiform to corymbiform arrays (often widely branching and subdichotomous, at least some branches elongate).
(1–2 in pedunculate lateral clusters) in spiciform or racemiform arrays.
golden brown to light tan, subcylindric, subterete or angled, 5–8 mm, indistinctly 8–10-ribbed;
pappi tan, 7–8 mm.
dark green, elliptic to linear, subterete to angular, 3.5–5.5 mm, indistinctly 8–10-ribbed;
pappi pale yellow to tan, 5 mm.
= 16.
Prenanthes serpentaria
Prenanthes autumnalis
Prenanthes serpentaria is generally recognized by its large, deeply 3–5-lobed proximal leaves with rounded sinuses and lobes, winged petioles, attenuate involucres, sparsely setose phyllaries, and yellow corollas. The leaves are variable in size and lobing, often on the same plant. Some specimens have predominantly ovate to elliptic, unlobed leaves, and these have been variously recognized. Some specimens appear to combine characteristics of P. crepidinea or P. trifoliolata and may be the result of recent or ancient hybridization. The species boundaries in this group merit further study.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Prenanthes autumnalis is recognized by its erect, slender habit, pinnately lobed proximal leaves, narrowly racemiform or spiciform arrays of heads, glabrous phyllaries, and usually pinkish corollas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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