3. Prenanthes aspera Michx. (rattlesnake root, rough white lettuce)
Nabalus asper (Michx.) Torr. & A. Gray
Pl. 261 h–j; Map
1092
Stems 35–170 cm
long, slender to somewhat stout, moderately to densely pubescent with short,
spreading hairs and minute, curled hairs above the midpoint, often glabrous or
nearly so toward the base, often purplish-tinged or with dark purple mottling,
not glaucous. Leaves with both surfaces minutely roughened, the undersurface
also with short, stiff, stout hairs and often also inconspicuously pubescent
with short, curled hairs along at least the main veins, not glaucous. Basal and
lowermost stem leaves sessile to more commonly short-petiolate, the blade 4–11
cm long, more or less obovate, the margins entire or with few to several often
irregular, fine teeth or rarely shallow lobes. Lower, median, and upper leaves
gradually reduced, sessile, the blade entire or more commonly finely toothed,
rarely more deeply toothed or shallowly pinnately lobed, narrowly lanceolate to
lanceolate, oblong-elliptic, or rarely ovate. Inflorescences appearing spicate,
as narrowly cylindrical panicles, or as small, dense axillary clusters of heads
along an unbranched main stem, the heads mostly ascending. Involucre 12–17 mm
long, the inner bracts (6–)8–10, narrowly rounded to more commonly sharply
pointed at the tip, the surface pubescent with relatively coarse, stiff,
spreading to ascending hairs, the margins frequently pubescent with minute,
curled hairs toward the tip, yellowish green to pale green, often with a darker
green to dark purplish-tinged base and/or tip (often darkening further upon
drying), not glaucous or pebbled. Ligulate florets (8–)11–14(–19). Corollas 9–17
mm long, cream-colored to pale yellow. Pappus 6–8 mm long, usually
straw-colored. Fruits 5–6 mm long, usually bright yellowish brown. 2n=32.
August–October.
Scattered nearly
throughout the state, but apparently absent from parts of the northwestern and
southeastern portions (South Dakota to Pennsylvania south to Oklahoma,
Louisiana, and Alabama). Upland prairies, glades, openings
of mesic to dry upland forests, and savannas; also railroads and roadsides.
Steyermark
(1963) remarked that the florets of this species produce a “pleasantly
delicious fragrance resembling that of Sabatia angularis
[Gentianaceae].” He also noted the existence of a putative hybrid with P.
crepidinea from Greene County.