Arnica. COMPOSITiE. 403 



41. ARNICA. Linn. ; Endl. gen. 2800. vl/?A7C 



[ Said to be a corruption ot Ptarmica.] 



Heads many-flowered, radiate ; the ray-flowers pistillate, but often with sterile stamens ; 

 disk-flowers tubular, perfect, 5-toothed. Involucre campanulate '; the scales lanceolate, 

 equal, somewhat in a double series. Receptacle flat, fibrillate or a little hairy. Style in 

 the disk-flowers with long pubescent branches, truncate, or tipped with a short cone. 

 Achenia terete, tapering to the base or fusiform, somewhat hairy. Pappus a single series 

 of rather rigid scabrous or plumose-barbellate bristles. — Perennial herbs, with undivided 

 opposite leaves, and rather large solitary or loosely corymbose heads. Flowers yellow. 



1. Arnica mollis. Hook. (Plate LX.) Soft Arnica. 



Villous-pubescent; steam leafy, bearing 1 - 5 heads; leaves lanceolate or oblong, smoothish 

 when old, repandly denticulate ; the cauline 3-5 pairs ; the upper closely sessile, the lower 

 narrowed at the base or tapering into a petiole ; scales of the involucre acuminate, hairy ; 

 achenia almost plumose.— ifooA:. fl. Bor.-Am. l.p. 331 ; Torr. 4- Gr. fl. N. Am. 2. p. 45o! 



Root creeping. Stem 12-20 inches high, simple, more or less pubescent, especially above. 

 Leaves 3-5 inches long and about an inch wide, thin, veiny ; the lower on rather long winged 

 petioles, and somewhat triplinerved ; upper ones somewhat connate, acuminate. Heads 

 commonly 3, nearly two inches in diameter. Rays about 12, 2 - 3-toothed at the extremity, 

 pale yellow. 



Borders of rivulets in the mountains of Essex county. August. 



Tribe V. CYNARE^. Less. 

 Heads homogamous or heterogamous, sometimes dioecious. Style in the perfect flowers often 

 abruptly thickened near the summit ; the branches either distinct or united, jmbescent 

 externally ; the stigmatic lines reaching to their apex, and there confluent. 



CONSPECTUS OF THE GENERA. 

 Subtnbo I. CENTAURIEjE. Heails iliscoid ; the marginal flowers mostly neutral, usually much larirer than 

 the others. Pappus never plumose, sometimes wanting. 



42. Centaorea. Achenia compressed. Pappus of filiform bristles, or none. 



43. Ckicus. Achenia terete, strongly striate. Pappus triple ; the exterior 10-toothcd, the intermediate of 10 long bristles, 



the inner of 10 short bristles. Marginal flowers sterile, small. 



Subtribell. CARDUINEiE. Heads discoid, homogamous, sometimes dicccious. Anthers slightly or not at 

 all caudate. Pappus of plumose or rough bristles, 



44. CiBsiCM. Achenia smooth. Pappus plumose. Receptacle bristly. 



43. Lapp*. Achenia rugose. Pappus rough, caducous. Roccptaclo BCtosc-fimbrillatc. Scales of the involucre hooked 

 at the apex. 



61* 



