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FNA | Family List | FNA Vol. 19, 20 and 21 | Asteraceae | Prenanthes

5. Prenanthes autumnalis Walter, Fl. Carol. 193. 1788.

Slender rattlesnakeroot

Nabalus virgatus de Candolle; Prenanthes virgata Michaux

Plants 40–140 cm; taproots thickened, tuberous. Stems 1–5, erect, mostly green with mottled purple, slender, simple, glabrous. Leaves: 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. Heads (1–2 in pedunculate lateral clusters) in spiciform or racemiform arrays. Involucres cylindro-campanulate, 10–13 × 3–4 mm. Calyculi of 6–8, green to purple, triangular to subulate bractlets 1–4 mm. Phyllaries 7–8, pink or purple, linear to elliptic, 8–13 mm, glabrous. Florets 8–10; corollas usually pinkish. sometimes lavender or white, 11–17 mm. Cypselae dark green, elliptic to linear, subterete to angular, 3.5–5.5 mm, indistinctly 8–10-ribbed; pappi pale yellow to tan, 5 mm.

Flowering Aug–Oct. Coastal plain, low savannas, sandy pinelands, moist places, swales; 0–200 m; Del., Fla., Ga., Md., Miss., N.J., N.C., S.C., Va.

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.


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