COMPOSITAE (COMPOSITE FAMILY) 571 



86. PETASITES L. BUTTERBUR. SWEET COLTSFOOT 



Perennial herbs, with thickish and creeping rootstocks sending up scapi- 

 form simple flowering stems and ample radical leaves on strong petioles, 

 cottony-tomentose or glabrate. Flowers whitish or purplish. Involucre a 

 series of soft herbaceous bracts. Heads subdioecious, racemosely or corym- 

 bosely disposed. Achenes narrow, 5-10-costate, with elongating soft and 

 white pappus. 



1. Petasites sagittate Gray, Bot. Cal. 1: 407. 1880. Leaves deltoid-oblong 

 to reniform-hastate, acute to rounded-obtuse, repand-dentate, very white- 

 tomentose beneath, when full grown 1.5-2 dm. long: heads short-racemose 

 becoming corymbose. Wet ground; in the mountains of Colorado and north- 

 ward; across the continent in northern latitudes. 



87. HAPLOESTHES Gray 



Herbs with opposite leaves. Heads radiate; flowers all fertile. Invo- 

 lucre short-campanulate, of 4-5 similar, rather fleshy, orbicular or broadly 

 oval bracts, the outer strongly overlapping the inner. Ligules of the rather 

 few and short ray-flowers oval. Achenes linear, terete, striate-costate, gla- 

 brous. Pappus a single series of rather rigid and scabrous whitish bristles. 



1. Haploesthes Greggii Gray, PL Fendl. 109. 1859. Somewhat fleshy, 

 herbaceous or suffrutescent, 3-6 dm. high, fastigiately branched, glabrous, 

 leafy up to the loose cymes of a few slender-pedunculate naked heads: leaves 

 all opposite, very narrowly linear or filiform, entire; the lower connate at base: 

 heads 4-6 mm. high: flowers yellow: ligules 2-4 mm. long. Saline soil; 

 southeast Colorado to western Texas. 



88. ARNICA L. 



Perennial herbs with erect stems, mostly opposite leaves, and comparatively 

 large heads of yellow flowers. Heads many-flowered, conspicuously radiate, 

 or t lu- rays rarely wanting. Involucre campanulate, of several thin-herbaceous 

 oblong-lanceolate to linear equal bracts in a single or somewhat double series. 

 Receptacle flat, sometimes fimbrillate or villous. Corollas of the disk-flowers 

 with a commonly elongated hirsute tube and funnelform or cylindraceous 

 5-lobed limb. Achenes linear, more or less 5-10-costate or angled. Pappus 

 a single series of numerous rather rigid capillary bristles, scabrous to barbel- 

 late, or subplumose. 



Heads radiate. 



Radical or rhizome leaves in fascicles, long-petioled, and with broad 



and more or less cordate blade. 

 Stem leaves evidently cordate, at least the lower. 



He;u Is mostly solitary and long-pedunculate .... 1. A. cordifolia. 



Heads corymbose or paniculate . . . . . 2. A. paniculata. 



Stem leaves suborbicular to ovate-lanceolate. 



Plants tall, 4-8 dm. high, with large thin subsessile leaves . 3. A. ventorum. 

 Plants rarely 3 dm. high. 



Leaves glabrate; heads one or more, usually several, the in- 

 volucres turbinate . . . . . . 4. A. gracilis. 



Leaves sparsely but evidently pubescent; heads one or more 



but usually solitary, the involucres hemispherical . 5. A. pumila. 



No cordate leaves. 



Fascicles of oblong or obovate radical or rhizome leaves present. 

 Involucre turbinate-campanulate, nearly glabrous. 



Stem leaves large, broadly ovate or elliptic, thin . . . 3. A. ventorum. 

 Stem leaves small, ovate or ovate-lanceolate, acute or acumi- 

 nate . . . . . . . . . . 4. A. gracilis. 



Involucre broadly hemispherical, hirsute . . . 6. A. subplumosa. 



Fascicles of radical or rhizome leaves usually wanting, if present 



lanceolate or oblanceolate. 

 Stems leafy throughout. 



Not growing in tufts, the plants mostly single. 



