Prenanthes serpentaria
Prenanthes crepidinea
butterweed, cankerweed, gall-of-the-earth, lion's-foot
nodding rattlesnakeroot
erect, green to reddish or purple mottled, proximally glabrous, distally sparsely tomentulose.
erect, green to tan, glabrous proximally, tomentose 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; petiolate (petioles winged, 1–13 cm, margins sometimes serrate);
blades deltate to broadly ovate, 8–23 × 3–14 cm, coriaceous, bases hastate or sagittate, margins entire or coarsely dentate to serrate (teeth often large and remote), faces glabrous or scabrous, hirsute along veins;
distal petiolate or sessile, ovate or elliptic, entire.
cylindric (often attenuate basally to bracteate peduncles), 12–15 × 4–5 mm.
campanulate, 12–16 × 7–14 mm.
(8–)10–14(–19);
corollas usually yellow to pale yellow, 9–15 mm.
15–38;
corollas usually white, sometimes yellow, 9–15 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).
9–15, dark green to blackish, lanceolate to elliptic, 10–16 mm, margins scarious, moderately to densely, ± coarsely setose on midribs.
of 8–10, green to purple, triangular to subulate bractlets 1–4 mm, often tomentulose to setose.
of 18–20 dark green, triangular to lanceolate bractlets 2–5 mm, coarsely setose.
(6–12 in nodding clusters) in broad, paniculiform to corymbiform arrays (often widely branching and subdichotomous, at least some branches elongate).
in broad, open, (leafy) paniculiform arrays (branches often elongate, nodding).
golden brown to light tan, subcylindric, subterete or angled, 5–8 mm, indistinctly 8–10-ribbed;
pappi tan, 7–8 mm.
golden brown, oblong to linear, subterete to angled, 5–6 mm, unequally 10–12-ribbed;
pappi tan, 6–8 mm.
= 16.
= 32
Prenanthes serpentaria
Prenanthes crepidinea
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 crepidinea is generally recognized by its tall and robust habit, large deltate or ovate proximal leaves, coarsely dentate margins with relatively large, remote teeth, heads borne in open, paniculiform arrays, dark green or blackish and moderately to densely setose phyllaries, and white or yellow corollas. In some areas P. crepidinea and P. serpentaria overlap in leaf morphology and corolla color, perhaps indicative of past hybridization, and can be difficult to distinguish. Prenanthes serpentaria is generally smaller in stature, has more elongate, pinnately lobed leaves with rounded sinuses, more sparsely setose phyllaries, and yellow or greenish yellow corollas. Prenanthes crepidinea appears to favor moist, bottomland sites, in contrast to the drier and acidic upland habitats preferred by P. serpentaria. Prenanthes crepidinea appears to hybridize with P. aspera in southeastern Missouri (J. A. Steyermark 1963).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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