Prenanthes serpentaria
Prenanthes trifoliolata
butterweed, cankerweed, gall-of-the-earth, lion's-foot
dwarf rattlesnakeroot, gall of the earth, prenanthe trifoliolée, threeleaf rattlesnakeroot
erect, green to reddish or purple mottled, proximally glabrous, distally sparsely tomentulose.
erect, green or sometimes mottled purple, usually glabrous, sometimes 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 usually present at flowering; petiolate (petioles winged, 1–25 cm);
blades deltate to ovate, 3–12 × 1–15 cm, thin, bases cordate to rounded, margins palmately 3(–5)-lobed to -divided (then leaves compound), lobes and sinuses usually angular (not rounded), lobes short and lanceolate, ultimate margins irregularly serrate, faces glabrous or ciliate along abaxial veins and margins;
distal reduced, palmately lobed or entire.
cylindric (often attenuate basally to bracteate peduncles), 12–15 × 4–5 mm.
narrowly campanulate (bases attenuate to bracteate peduncles), 10–13 × 4–5 mm.
(8–)10–14(–19);
corollas usually yellow to pale yellow, 9–15 mm.
8–13;
corollas pale 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).
7–10, green to dark green or blackish proximally, lanceolate to elliptic, 10–11 mm, margins scarious, sometimes ciliate, faces glabrous.
of 8–10, green to purple, triangular to subulate bractlets 1–4 mm, often tomentulose to setose.
of 5–7, green to dark green or blackish, triangular bractlets 1–3 mm, glabrous.
(6–12 in nodding clusters) in broad, paniculiform to corymbiform arrays (often widely branching and subdichotomous, at least some branches elongate).
(2–7, nodding, in irregular clusters) in 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.
tan to brown, subcylindric, subterete to angled, 4–5 mm, distinctly 8–11-ribbed;
pappi pale yellow, 7–9 mm.
= 16.
= 16.
Prenanthes serpentaria
Prenanthes trifoliolata
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 trifoliolata is recognized by its relatively large, palmately 3–5-lobed leaves with angular lobes and sinuses, basally attenuate involucres, dark green and glabrous calyculi and phyllaries, and pale yellow corollas. Dwarf plants with deeply parted leaves found in alpine areas of northern New England and Canada have been recognized as P. nana or P. trifoliolata var. nana. This form is probably no more than a phenotypic adaptation to harsh environments. In at least some localities, it intergrades with more typical P. trifoliolata at lower elevations.
Hybrids between Prenanthes trifoliolata and P. racemosa, known as P. ×mainensis A. Gray, have been found in Maine, New Brunswick, Nova Scotia, and southern Quebec, usually where the two parents come together in cliff or saline habitats. The leaves of the hybrids are intermediate between 3-lobed and spatulate, the distal are sessile, the heads are nodding, and the phyllaries are glabrous, as in the P. trifoliolata parent.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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USDA Plants Database
MI Flora
