Prenanthes alba |
Prenanthes autumnalis |
|
---|---|---|
prenanthe blanche, white lettuce, white rattlesnake-root |
slender rattlesnakeroot |
|
Habit | Plants 20–175 cm; taproots short and thickened, fibrous. | Plants 40–140 cm; taproots thickened, tuberous. |
Stems | erect, often mottled purple or nearly all purple (often with stout bases, 8–12 mm diam.), proximally glabrous, tomentulose distally. |
1–5, erect, mostly green with mottled purple, slender, simple, glabrous. |
Leaves | proximal present at flowering; petioles narrowly winged (to 18 cm); blades usually ovate to triangular or cordate, 4–30 × 3–18 cm, thin to coriaceous, bases often hastate, margins usually coarsely dentate or serrate, sometimes deeply 3-lobed or parted, lobes acute, faces glabrous adaxially, pale to whitish and sometimes hirsute abaxially; distal reduced. |
proximal present at flowering; petiolate (petioles winged); blades oblong to linear, 7–18 × 0.5–6 cm, coriaceous, bases attenuate, margins deeply pinnately lobed or divided, lobes narrow and at right angles, apices acute to acuminate, faces glabrous or slightly glabrate along veins; distally sessile and much reduced. |
Involucres | cylindric to campanulate, 13–15 × 3–5 mm. |
cylindro-campanulate, 10–13 × 3–4 mm. |
Florets | 7–9(–13); corollas whitish to pale pink, lavender or red, 9–15 mm. |
8–10; corollas usually pinkish, sometimes lavender or white, 11–17 mm. |
Phyllaries | (6–)8(–9), ± purplish or maroon, lanceolate, 10–13 mm, margins scarious, minutely ciliate, apices acute, faces glabrous. |
7–8, pink or purple, linear to elliptic, 8–13 mm, glabrous. |
Calyculi | of 5–7, triangular to lanceolate bractlets 1–3 mm, glabrous. |
of 6–8, green to purple, triangular to subulate bractlets 1–4 mm. |
Heads | (3–8, in clusters) in paniculiform arrays (densest near apices). |
(1–2 in pedunculate lateral clusters) in spiciform or racemiform arrays. |
Cypselae | brown or tan, elliptical to linear, 3.5–6 mm; pappi usually reddish brown, sometimes rusty, rarely yellowish, 6–7 mm. |
dark green, elliptic to linear, subterete to angular, 3.5–5.5 mm, indistinctly 8–10-ribbed; pappi pale yellow to tan, 5 mm. |
2n | = 32. |
|
Prenanthes alba |
Prenanthes autumnalis |
|
Phenology | Flowering Aug–Oct. | Flowering Aug–Oct. |
Habitat | Sandy oak-scrub, open oak-hickory woods, deciduous forests, dunes, creek banks, road cuts | Coastal plain, low savannas, sandy pinelands, moist places, swales |
Elevation | 100–200 m (300–700 ft) | 0–200 m (0–700 ft) |
Distribution |
AR; CT; DE; GA; IA; IL; IN; KY; MA; MD; ME; MI; MN; MO; NC; ND; NH; NJ; NY; OH; PA; RI; SD; TN; VA; VT; WI; WV; MB; ON; QC; SK
|
DE; FL; GA; MD; MS; NC; NJ; SC; VA |
Discussion | Prenanthes alba is recognized by the purplish stems, relatively large, coarse, ovate or triangular leaves, relatively long, winged petioles, glabrous and often purple phyllaries, and usually reddish brown pappi. The leaves are variable, occasionally deeply 3-lobed. W. L. Milstead (1964) recognized specimens with a pale yellow pappi as “subsp. pallida,” distributed on the east coast in New Jersey, Virginia, and North Carolina. Because pappus color tends to fade somewhat on herbarium specimens, that character is difficult to assess on older specimens. The name was not validly published. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Prenanthes autumnalis is recognized by its erect, slender habit, pinnately lobed proximal leaves, narrowly racemiform or spiciform arrays of heads, glabrous phyllaries, and usually pinkish corollas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 266. | FNA vol. 19, p. 267. |
Parent taxa | Asteraceae > tribe Cichorieae > Prenanthes | Asteraceae > tribe Cichorieae > Prenanthes |
Sibling taxa | ||
Synonyms | Nabalus albus | Nabalus virgatus, P. virgata |
Name authority | Linnaeus: Sp. Pl. 2: 798. (1753) | Walter: Fl. Carol., 193. (1788) |
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