COMPOSITAE. 1023 



toothed at the apex; achenes hirsute-pubescent, or glabrous at the base. Western 

 Neb. to S. Dak., the N, W. Terr., Nev. and Br. Col. May-July. 



;: Arnica lance olta Nutt. NORTHERN ARNICA. (I. F. f. 4026.) Sparingly 

 villous-pubescent; stem simple, or little branched, 3-7 dm. high, bearing 1-6 

 heads at the summit. Leaves oblong or oblong-lanceolate, dentate or entire, acute 

 or obtuse, 5-12 cm. long, 6-18 mm. wide, the lower and basal ones narrowed into 

 petioles, the upper sessile, and usually somewhat connate by a broad or narrowed 

 base, those of the stem 3-5 pairs, usually with some alternate small ones on the 

 branches; heads 2-5 cm. broad; bracts of the involucre acute; rays 10-15, 3-toothed: 

 achenes hirsute-pubescent. Mountains of northern N. Y., N. H. and Me. to N. B., 

 west to Lake Superior. June-Aug. It has been confused with the grayish 

 pubescent A. Chamissonis of the west. 



4. Arnica alpina (L.) Olin. MOUNTAIN TOBACCO. ARCTIC ARNICA. (I. F. 

 f. 4027.) Similar to the preceding species, but smaller and more slender, 15-35 

 cm. high, villous or pubescent. Stem simple, usually bearing but a single head; 

 leaves lanceolate, linear-oblong, or the lowest spatulate, thickish, entire or dentic 

 ulate, 3-nerved, the basal ones petioled, those of the stem 1-3 pairs, sessile or 

 short-petioled, scarcely connate, the upper pair usually much smaller than the 

 lower ones; heads about 5 cm. broad; rays 10-15, toothed; achenes hirsute or 

 glabrate. Labrador to Greenland and the Arctic Sea. Also in northern Europe. 

 May-Sept 



93- ERECHTITES Raf. 



Erect, usually branching herbs, with alternate leaves, and (in our species) 

 rather large discoid many-flowered heads of whitish flowers, corymbose-paniculate 

 at the ends of the stem and branches. Involucre cylindric, swollen at the base, its 

 principal bracts in I series, linear, with or without some much smaller outer ones. 

 Receptacle concave, naked. Marginal flowers in 2-several series, pistillate, fertile, 

 their corollas filiform, the limb 2-4- toothed. Central flowers perfect, fertile; corolla 

 narrowly tubular, the limb 4-5 -toothed, the style-branches elongated, truncate or 

 obtuse at the summit. Anthers obtuse and entire at the base. Achenes linear- 

 oblong, angled or striate. Pappus of copious caspillary soft smooth white bristles. 

 [Ancient name of some groundsel.] About 12 species, natives of America and 

 Australasia. The following is the only one known to occur in North America. 



i. Ercchtites hieracifolia (L.) Raf. FIRE-WEED. PILEWORT. (I. F. f. 

 4028.) Annual, glabrous, or somewhat hirsute; stem striate, succulent, usually 

 branched, 3-25 dm. high. Leaves thin, lanceolate or ovate-lanceolate, dentate 

 and often deeply incised, 5-20 cm. long, the upper sessile or auriculate-clasping, 

 mostly acuminate, the lower usually narrowed into petioles ; heads 12-20 mm. long, 

 alxmt 6 mm. in diameter, the involucre conspicuously swollen at the base before 

 flowering, its bracts numerous, striate, green, with narrow scarious margins; pap- 

 pus bright white. In woodlands, thickets and waste places, Newf. to Fla., west to 

 the N. W. Terr., Neb., Kans. and La. Also in Mex. and S. Am. July-Sept 



94. MESADENIA Raf. 



Tall perennial mostly glabrous herbs, with alternate petioled leaves and nu- 

 merous, rather small, corymbose, discoid heads of white, yellowish or pinkish 

 flowers, all tubular and perfect. Sap milky (at least in some species). Involucre 

 cylindric or nearly so, its principal bracts 5, in I series, equal, usually with a few 

 short outer ones. Receptacle fl.it, not chaffy, with a fleshy projection in the center. 

 Corollas with somewhat spreading 5-cleft limbs, the lobes usually with a mid-nerve. 

 Style-branches conic or obtuse at the apex. Achenes oblong, glabrous. Pappus of 

 copious white scabrous bristles. [Greek, referring to the central projection of the 

 receptacle.] About 12 species, natives of North and Central America. Besides 

 the following, 4 others occur in the southern and southwestern U. S. 



Leaves thin, reniform or fan-shaped, lobed, or angulate-dentate. 



Leaves green both sides, annulate-dentate. I. M. reniformis. 



Leaves glaucous beneath, green above, angulate-lobed. 2. M. atriplicifolia, 



Leaves thick, green both sides, ovate or oval, entire, or repand. 3. M. tuberosa. 



