Prenanthes serpentaria
Prenanthes altissima
butterweed, cankerweed, gall-of-the-earth, lion's-foot
prenanthe élevée, tall rattlesnakeroot
erect, green to reddish or purple mottled, proximally glabrous, distally sparsely tomentulose.
erect, greenish to purplish, glabrous proximally, often tomentulose distally.
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;
petioles winged;
blades usually ovate or triangular, 4–15 × 2–16 cm, thin, bases truncate to hastate or cordate, margins entire or shallowly dentate, often deeply 3-lobed, faces glabrous or with scattered hairs on veins;
distal reduced in size and lobing.
cylindric (often attenuate basally to bracteate peduncles), 12–15 × 4–5 mm.
cylindric, 9–14 × 2–3 mm.
(8–)10–14(–19);
corollas usually yellow to pale yellow, 9–15 mm.
(4–)5(–6);
corollas pale yellow to greenish yellow, 7–15 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).
(4–)5(–6), pale green, often blackish at bases and apices, linear to lanceolate, 10–12 mm, glabrous or sparsely hairy.
of 8–10, green to purple, triangular to subulate bractlets 1–4 mm, often tomentulose to setose.
of 4–6, blackish, triangular bractlets 1–4 mm, glabrous.
(6–12 in nodding clusters) in broad, paniculiform to corymbiform arrays (often widely branching and subdichotomous, at least some branches elongate).
in narrow or spreading, paniculiform arrays.
golden brown to light tan, subcylindric, subterete or angled, 5–8 mm, indistinctly 8–10-ribbed;
pappi tan, 7–8 mm.
brown to tan, subcylindric, subterete, 4–5 mm, indistinctly 5–10-ribbed;
pappi usually whitish or pale yellow, sometimes reddish brown, 5–6 mm.
= 16.
= 16.
Prenanthes serpentaria
Prenanthes altissima
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 altissima is recognized by its narrow involucres with 5 pale green, glabrous phyllaries, (4–)5(–6) florets, and pale yellow to greenish yellow corollas. Pappi in this species are most commonly whitish or pale yellow. Specimens with reddish brown to orange pappi have been recognized as var. cinnamomea, found in Arkansas, Louisiana, and Missouri. Specimens with densely hairy stems and pale yellow pappi have been recognized as var. hispidula, found mostly in New York, New England, and adjacent Canada.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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