Prenanthes racemosa
Prenanthes crepidinea
glaucous rattlesnakeroot, glaucous white lettuce, prenanthe à grappe, purple rattlesnake-root
nodding rattlesnakeroot
erect, green or light purple, simple, (stout), glabrous and glaucous proximally, setose or hispid distally.
erect, green to tan, glabrous proximally, tomentose distally.
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.
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.
campanulate, 11–12 × 4–7 mm.
campanulate, 12–16 × 7–14 mm.
9–29;
corollas usually pinkish, sometimes white or lavender, 7–13 mm.
15–38;
corollas usually white, sometimes yellow, 9–15 mm.
7–14, green to purple, lanceolate to linear, 10–12 mm, margins scarious, sparsely to densely setose.
9–15, dark green to blackish, lanceolate to elliptic, 10–16 mm, margins scarious, moderately to densely, ± coarsely setose on midribs.
of 8, dark green to purple, narrowly triangular-subulate bractlets 2–4 mm, coarsely setose.
of 18–20 dark green, triangular to lanceolate bractlets 2–5 mm, coarsely setose.
(ascending) in (elongate) narrowly racemiform or paniculiform arrays.
in broad, open, (leafy) paniculiform arrays (branches often elongate, nodding).
golden brown, sub-cylindric, subterete, 5–6 mm, indistinctly 8–12-ribbed;
pappi pale yellow, 6–7 mm.
golden brown, oblong to linear, subterete to angled, 5–6 mm, unequally 10–12-ribbed;
pappi tan, 6–8 mm.
= 16.
= 32
Prenanthes racemosa
Prenanthes crepidinea
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.)
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.)
BC
Flora NW
IL Wildflowers
MI Flora
MN Wildflowers
MO Plants
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
