IO22 FLORA.^ 



sometimes becoming glabrate, the lobes oblong or obovate, acute, often somewhat 

 cuneate, sharply dentate or incised ; heads mostly dioecious, corymbose or racemose- 

 corymbose, numerous, 7-12 mm. broad; flowers nearly white, fragrant. In 

 swamps and along streams, Newf. to Alaska and Br. Col., south to Mass., N. Y., 

 Wis. and Cal. April-June. 



2. Petasites frigida (L.) Fries. ARCTIC SWEET COLTSFOOT. (I. F. f. 4021.) 

 Scape very scaly, 7-30 cm. high. Leaves 3-10 cm. long, irregularly and angulately 

 lobed and incised, green and glabrous above, persistently white-tomentose be- 

 neath, the lobes entire or few-toothed ; heads usually fewer and larger than those 

 of the preceding species ; involucre short-campanulate; flowers nearly white, fra- 

 grant. Lake Winnipeg to the Arctic Sea, west to Alaska and the mountains of Br. 

 Col. Also in northern Europe and Asia. June-Aug. 



3. Petasites sagittata (Pursh) A. Gray. ARROW-LEAF SWEET COLTSFOOT. 

 (I. F. f. 4022.) Scape and racemose-corymbose inflorescence similar to those of the 

 two preceding species. Leaves deltoid-ovate or reniform-ovate, persistently white- 

 tomentose beneath, glabrous or nearly so above, 1-3 dm. long, their margins sinuate- 

 denticulate, neither cleft nor lobed; involucre campanulate; flowers nearly white. 

 In wet ground, Hudson Bay to Manitoba and Minn., Br. Col., S. Dak. and Colo. 

 May-June. 



4. Petasites Petasites (L.) Karst. BUTTER-BUR. BUTTERFLY-DOCK. (I. 

 F. f. 4023.). Scape very scaly, 15-45 cm. high. Leaves orbicular or hastate-reni- 

 lorm, often 3 dm. broad when mature, rounded or pointed at the apex, repand- 

 denticulate all around, persistently white-tomentose beneath, green and mostly 

 glabrous above; heads 8-12 mm. broad, mostly direcious, in a dense raceme, the 

 staminate ones smaller than the pistillate. In cultivated and waste ground, Pa. 

 Nat. from Europe. Native also of northern Asia. April. 



92. ARNICA L. 



Erect, simple or little branched herbs, with opposite leaves, or the upper rarely 

 alternate, and large, long-peduncled heads of both tubular and radiate yellow 

 flowers, or rays wanting in some species. Involucre turbinate or campanulate, its 

 bracts in I or 2 series, narrow, nearly equal. Receptacle flat, naked, fimbrillate 

 or villous. Ray-flowers pistillate, fertile, the rays spreading, entire, or 2-3- 

 toothed. Disk-flowers perfect, fertile, the corolla 5 -lobed, the style with slender 

 branches. Anthers entire or minutely 2-auriculate at the base. Achenes linear, 

 5- lO-ribbed, more or less pubescent. Pappus a single series of rough or barbellate 

 rigid slender bristles. [Derivation uncertain, perhaps from Ptarmica.] About 30 

 species, natives of the northern hemisphere. Besides the following, some 20 others 

 occur in the western parts of North America. 



Basal leaves ovate or oval, sessile; southern. I. A. acaulis. 

 Basal leaves oblong, lanceolate, or cordate-ovate, petioled. 



Basal leaves cordate-ovate. 2. A. cordifolia. 

 Basal leaves not cordate, tapering to the petiole. 



Stem-leaves 3-5 pairs, the upper somewhat smaller. 3. A. lanceolata. 



Stem-leaves 1-3 pairs, the upper much smaller. 4. A. alpina. 



1. Arnica acaulis (Walt.) B.S.P. LEOPARD'S-BANE. (I. F. f. 4024.) Gland- 

 ular-hirsute; stem 3-9 dm. high, bearing several slender-peduncled heads at the 

 summit. Basal leaves tufted, ovate or oval, obtuse, narrowed to a sessile base, 

 denticulate or entire, 5-12 cm. long, 4-7 cm. wide; stem-leaves 1-3 pairs, and 

 some alternate, very small ones above; heads 25-35 mm. broad; bracts of the invo- 

 lucre linear-lanceolate, acute or acutish ; rays 12-15, commonly 3-toothed at the 

 truncate apex ; achenes pubescent when young, glabrous or nearly so when mature. 

 In low woods, Del. and southern Penn. to Fla. April-May. 



2. Arnica cordifolia Hook. HEART-LEAF ARNICA. (I. F. f. 4025.) Hirsute, 

 or pubescent; stem simple, or sparingly branched, 3-9 dm. high. Basal and 

 lower leaves ovate to nearly orbicular, obtuse or acute, deeply cordate at the base, 

 dentate, 3-7 cm. long, with slender sometimes margined petioles; stem- leaves 1-3 

 pairs, ovate to oblong, sessile or short- petioled, much smaller; heads 1-8, 5-7 cm. 

 broad; bracts of the involucre acute or acuminate, 12-20 mm. long; rays 12-16, 



