All Floras      Advanced Search
FNA Vol. 19, 20 and 21 Page 264, 265, 268 Login | eFloras Home | Help
FNA | Family List | FNA Vol. 19, 20 and 21 | Asteraceae | Prenanthes

7. Prenanthes boottii (de Candolle) D. Dietrich, Syn. Pl. 4: 1309. 1847 (‘bootii’).

Boott’s rattlesnakeroot

Nabalus boottii de Candolle in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 7: 241. 1838 (‘bootii’)

Plants 5–25 cm; taproots short, thick, tuberous. Stems decumbent to erect, mottled purple, simple, glabrous proximally, tomentulose distally. Leaves: proximal present at flowering; petiolate (petioles 2–8 cm, not winged); blades ovate to deltate, 2–8 × 0.5–3 cm, bases hastate or sagittate, margins entire or weakly dentate, faces glabrous; distal reduced, elliptic to lanceolate. Heads (10–20) in narrow, racemiform to thyrsiform arrays (nodding). Calyculi of 4–5, dark green to blackish, subulate bractlets 2–5 mm, glabrous. Involucres cylindro-campanulate, 10–11 × 5–6 mm. Phyllaries 8–11, dark green to almost black, lanceolate to subulate, 8–12 mm, faces glabrous. Florets 9–20; corollas white, 7–13 mm. Cypselae light tan to yellow, subcylindric, subterete to angled, 5–6 mm, indistinctly 7–10-ribbed; pappi pale yellow, 6–8 mm. 2n = 32.

Flowering Jul–Aug. Alpine areas above treeline, mountains; of conservation concern; 1500–2000 m; Maine, N.H., N.Y., Vt.

Prenanthes boottii is recognized by its relatively short, decumbent habit, deltate to hastate proximal leaves, entire or weakly dentate margins, glabrous and blackish green phyllaries, white corollas, and alpine habitat.


Related Objects  
  • Distribution Map
  • Map

     |  eFlora Home |  People Search  |  Help  |  ActKey  |  Hu Cards  |  Glossary  |