Prenanthes racemosa |
Prenanthes |
|||||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
glaucous rattlesnakeroot, glaucous white lettuce, prenanthe à grappe, purple rattlesnake-root |
cankerweed, gall-of-the-earth, prenanthe, rattlesnakeroot |
|||||||||||||||||||||||||||||||||||||||||||||||||||||
Habit | Plants 30–175 cm; taproots fusiform, tuberous. | Perennials, 5–250 cm; taprooted, often producing offshoots connected by slender rhizomes. | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Stems | erect, green or light purple, simple, (stout), glabrous and glaucous proximally, setose or hispid distally. |
1–5, usually erect, sometimes decumbent (P. bootii), usually simple (leafy), usually glabrous proximally, tomentulose distally. |
||||||||||||||||||||||||||||||||||||||||||||||||||||
Leaves | 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. |
basal and cauline; petiolate or sessile; blades deltate to triangular, or ovate to oblanceolate, or oblong to linear, or spatulate, margins often pinnately or palmately lobed (sometimes deeply cleft and appearing compound), ultimate margins entire or coarsely serrate or dentate (apices acute, obtuse, or rounded); distal leaves reduced in size and lobing. |
||||||||||||||||||||||||||||||||||||||||||||||||||||
Peduncles | not inflated distally, bracteate. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||
Involucres | campanulate, 11–12 × 4–7 mm. |
narrowly cylindric to campanulate (bases often attenuate), 2–14 mm diam. |
||||||||||||||||||||||||||||||||||||||||||||||||||||
Receptacles | slightly convex, smooth, glabrous, epaleate. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||
Florets | 9–29; corollas usually pinkish, sometimes white or lavender, 7–13 mm. |
4–38; corollas usually creamy white, pink, or lavender, rarely yellow or red (glabrous). |
||||||||||||||||||||||||||||||||||||||||||||||||||||
Phyllaries | 7–14, green to purple, lanceolate to linear, 10–12 mm, margins scarious, sparsely to densely setose. |
3–15 in 1 series, (yellow green or green to purple or blackish) subulate or linear to lanceolate or elliptic, equal, margins scarious, apices acute, faces glabrous, tomentulose, hispid, or coarsely setose. |
||||||||||||||||||||||||||||||||||||||||||||||||||||
Calyculi | of 8, dark green to purple, narrowly triangular-subulate bractlets 2–4 mm, coarsely setose. |
of 2–12, triangular to linear-lanceolate or subulate, unequal bractlets. |
||||||||||||||||||||||||||||||||||||||||||||||||||||
Heads | (ascending) in (elongate) narrowly racemiform or paniculiform arrays. |
(usually nodding at flowering) in racemiform, paniculiform, thyrsiform, or corymbiform arrays. |
||||||||||||||||||||||||||||||||||||||||||||||||||||
Cypselae | golden brown, sub-cylindric, subterete, 5–6 mm, indistinctly 8–12-ribbed; pappi pale yellow, 6–7 mm. |
golden brown to light tan, narrowly subcylindric, or fusiform to oblanceoloid, or oblong to linear, subterete or angled, apices truncate, not beaked, faces finely 5–12-ribbed, usually glabrous; pappi persistent, of 30–50, dull white to yellow or tan, rarely reddish brown, ± equal, barbellulate bristles in 1 series. |
||||||||||||||||||||||||||||||||||||||||||||||||||||
x | = 8. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||
2n | = 16. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||
Prenanthes racemosa |
Prenanthes |
|||||||||||||||||||||||||||||||||||||||||||||||||||||
Phenology | Flowering Aug–Sep. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Habitat | Sandy alluvial soils of stream banks, wet meadows, tall-grass prairies, fens, marshy flats, bogs (mainly calcicolous, at least in north) | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Elevation | 0–2800 m (0–9200 ft) | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Distribution |
CO; IA; IL; IN; KY; ME; MI; MN; MO; MT; ND; NE; NJ; NY; OH; PA; SD; VT; WA; WI; WY; AB; BC; MB; NB; NF; NS; ON; QC; SK
|
North America; n Asia; sc Africa (1 species) |
||||||||||||||||||||||||||||||||||||||||||||||||||||
Discussion | 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.) |
Species ca. 26–30 (14 in the flora). Prenanthes is recognized by the erect and simple habit, deeply divided proximal leaves, whitish, yellow, or pinkish corollas in nodding heads, calyculate involucres, and pappi of barbellulate bristles. Leaf shape, size, and degree of lobing are often used for distinguishing species but are sometimes exceptionally variable. The proximal leaves are usually different in size, shape, and lobing from the distal leaves. Other taxonomic characters include size and habit, corolla color, number of florets per head, and phyllary number, color, and indument. The cypselae and pappi tend to be uniform. Molecular ITS studies by S. C. Kim et al. (1996) suggested that Prenanthes, as here circumscribed, may be polyphyletic; additional sampling including North American taxa is needed to confirm the relationships of Prenanthes and recognition of Nabalus Cassini at the genus level. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
||||||||||||||||||||||||||||||||||||||||||||||||||||
Key |
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||
Source | FNA vol. 19, p. 269. | FNA vol. 19, p. 264. | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Parent taxa | Asteraceae > tribe Cichorieae > Prenanthes | Asteraceae > tribe Cichorieae | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Sibling taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
Subordinate taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
Synonyms | Nabalus racemosus, P. racemosa subsp. multiflora, P. racemosa var. pinnatifida | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | Michaux: Fl. Bor.-Amer. 2: 84. (1803) | Linnaeus: Sp. Pl. 2: 797. (1753): Gen. Pl. ed. 5, 349. (1754) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Web links |