Prenanthes serpentaria
Prenanthes racemosa
butterweed, cankerweed, gall-of-the-earth, lion's-foot
glaucous rattlesnakeroot, glaucous white lettuce, prenanthe à grappe, purple rattlesnake-root
erect, green to reddish or purple mottled, proximally glabrous, distally sparsely tomentulose.
erect, green or light purple, simple, (stout), glabrous and glaucous proximally, setose or hispid 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 usually present at flowering;
petioles broadly winged, (1–15 cm);
blades broadly oblanceolate to spatulate, 4–25 × 1–8 cm, coriaceous, bases attenuate, clasping, margins entire or weakly denticulate, apices obtuse or rounded, faces glabrous;
mid cauline sessile, clasping;
distal sessile and reduced.
cylindric (often attenuate basally to bracteate peduncles), 12–15 × 4–5 mm.
campanulate, 11–12 × 4–7 mm.
(8–)10–14(–19);
corollas usually yellow to pale yellow, 9–15 mm.
9–29;
corollas usually pinkish, sometimes white or lavender, 7–13 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).
7–14, green to purple, lanceolate to linear, 10–12 mm, margins scarious, sparsely to densely setose.
of 8–10, green to purple, triangular to subulate bractlets 1–4 mm, often tomentulose to setose.
of 8, dark green to purple, narrowly triangular-subulate bractlets 2–4 mm, coarsely setose.
(6–12 in nodding clusters) in broad, paniculiform to corymbiform arrays (often widely branching and subdichotomous, at least some branches elongate).
(ascending) in (elongate) narrowly racemiform or paniculiform arrays.
golden brown to light tan, subcylindric, subterete or angled, 5–8 mm, indistinctly 8–10-ribbed;
pappi tan, 7–8 mm.
golden brown, sub-cylindric, subterete, 5–6 mm, indistinctly 8–12-ribbed;
pappi pale yellow, 6–7 mm.
= 16.
= 16.
Prenanthes serpentaria
Prenanthes racemosa
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 racemosa is recognized by its erect, stout, simple habit, glaucous stems, spatulate proximal leaves with broadly winged petioles and rounded to obtuse apices, heads borne in narrow racemiform arrays, purple and hairy phyllaries, and usually pinkish corollas. It is most similar to P. aspera, which differs in its generally smaller stature, more hirsute stems, leaves that are hispid abaxially, proximal leaves usually withered by flowering, and creamy white or yellow corollas. Hybrids between P. racemosa and P. trifoliolata, known as P. ×mainensis, occur in the northeastern United States and southeastern Canada (see discussion under P. trifoliolata).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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