574 COMPOSITAE (COMPOSITE FAMILY) 



largest; disk 10-12 mm. high, exceeding the oblong, obtusish bracts, about 15 

 mm. broad; rays about 1 cm. long; lateral heads somewhat reduced; pedicels 

 variable, rather slender, very lightly woolly-pubescent: achenes nearly gla- 

 brous, lightly striate, about equaling the soft pappus. (A. ocreata A. Nels. 1. c. 

 30: 201, from which this description is drawn.) On moist bottom lands at 

 middle altitudes; Colorado to Montana and westward. 



10. Arnica celsa A. Nels. 1. c. 31: 408. Stems from horizontal rootstocks, 

 erect, tall, 4-6 dm. high, lightly striate, sparsely pubescent with flat spread- 

 ing hairs, upwardly becoming also obscurely glandular- viscid : leaves (exclu- 

 sive of the foliar bracts) 6-8 pairs, puberulent and sprinkled with microscopic, 

 shining resin particles, narrowly oblong or oblanceolate, tapering to both 

 ends, many of them 3-nerved; the lower small, 2-3 cm. long, equaled by the 

 slender petioles which abruptly dilate into the equally long sheaths; middle 

 stem leaves longest (8-10 cm.), sessile or with short petioles and sheaths; 

 lower internodes short, much exceeded by the leaves, gradually longer up- 

 wards and above much exceeding the leaves: heads 3-5, on rather slender 

 leafy-bracted peduncles; involucral bracts uniserial, oblong, shorter than 

 the 12-15 mm. high disk: rays 12-20, 10-14 mm. long: tube of disk-corollas 

 slender and pubescent below: achenes subglabrous, nearly linear. Rich, 

 moist soils of stream banks; Wyoming and Colorado. 



11. Arnica longifolia Eat. in Wats. Bot. King's Exp. 186. 1871. Minutely 

 scabrous-puberulent ; stems 3-6 dm. high, many from a. scaly caudex: leaves 

 in 5-6 pairs, elongated-lanceolate, acuminate, 15-20 mm. broad, entire or 

 denticulate; the upper pairs sessile and slightly connate-amplexicaul ; the lower 

 with sheathing connate petioles; the very lowest reduced to sheathing scales: 

 heads few-many, not large; involucral bracts lanceolate, acute: achenes 

 minutely glandular but not hispid. (A. polycephala A. Nels. 1. c. 30' 202.) 

 In dense clumps among the rocks; infrequent; Colorado to Montana and far 

 westward. 



12. Arnica arcana A. Nels. 1. c. 37: 276. 1904. Tufted or caespitose in 

 rock crevices, about 3 dm. high, minutely granular-glandular: leaves dark 

 green, denticulate; root leaves oblong-ob lanceolate, 2-4 cm. long, on slender 

 petioles longer than the blade ; lower stem leaves small, broadly oblong, sub- 

 acute at apex, abruptly narrowed at base to short-margined connate-sheathing 

 petioles; middle stem leaves lanceolate, sessile or nearly so, 3-5 cm. long: 

 heads usually 3, on subequal peduncles 5-10 cm. long; rarely 1 or 2 smaller 

 ones; involucre turbinate-campanulate, about 1 cm. high, the bracts in 2 series; 

 the outer broadly linear, short-acuminate, minutely glandular; the inner 

 narrower, subscarious: rays orange-yellow, obscurely 3-toothed: disk-corollas 

 with narrow, minutely pubescent tube as long as the gradually dilated throat : 

 achenes linear, dark, sparsely hispidulous. Big Horn Mountains, Wyoming. 



13. Arnica Rydbergii Greene, Pitt. 4: 37. 1899. Generally 2-4 dm. high, 

 striate, sparingly hirsute, usually with 3 or 4 pairs of stem leaves, and 3 heads: 

 basal leaves ovate-lanceolate with a winged petiole, sinuately dentate, acute ; 

 stem leaves similar, sessile, with a broad, clasping, sometimes slightly dilated 

 base: heads decidedly turbinate, 12-15 mm. high; the bracts rather few, 8-16, 

 lanceolate, sparingly hirsute and puberulent: achenes silky-pubescent. (A. 

 caespitosa A. Nels. 1. c.; A. tennis Rydb. 1. c.; A. aurantiaca Greene, Torreya 

 1: 42. 1901.) On dry mountain slopes; Colorado to Montana and Washington. 



14. Arnica fulgens Pursh, Fl. 2: 527. 1814. Pubescent, hirsute, or at 

 summit yillous; stems 2-4 dm. high, strict, simple, usually monocephalous : 

 leaves thickish, narrowly oblong to lanceolate or the radical oblong-spatulate 

 and small, uppermost linear, entire or denticulate, 3-nerved; base of the 

 cauline barely or not at all connate : heads conspicuously radiate, solitary or 

 very few, mostly long-peduncled : achenes hirsute-pubescent, rarely glabrate. 

 A. alpina. (A. pedunculata Rydb. Bull. Torr. Bot. Club 24: 297. 1897; A. 

 monocephala Rydb. Mem. N. Y. Bot. Gard. 1: 435. 1900.) Colorado to Mon- 

 tana and far northwestward. 



15. Arnica stricta A. Nels. 1. c. 31: 407. Very erect, 2-3 dm. high, tomen- 

 tose-pubescent throughout: leaves about 5 pairs, the lower 2 or 3 pairs petioled, 



