980 FLORA. 



petioled, the upper sessile, somewhat clasping; heads few. 4-7 cm. broad; rays 

 10-15, linear-oblong, bright yellow ; exterior bracts of the cup-like involucre ovate- 

 oblong, obtuse, ciliate, 8-20 mm. long; achenes slightly oblique and laterally com- 

 pressed, nearly 6 mm. long. In rich woods, N. Y. to Ind. and Mich., Fla., Mo. 

 and Tex. July-Aug. 



2. Polymnia Canadensis L. SMALL-FLOWERED LEAF-CUP. (I. F. f. 3863.) 

 Rather slender, viscid-pubescent, at least above, 6-15 dm. high. Leaves deltoid- 

 ovate to hastate, usually very thin, all petioled, deeply angulate-lobed and the 

 lobes dentate, or the lower lyrate-pinnatifid, 12.5 dm. long, the upper ones some- 

 times ovate and entire or merely denticulate; heads few, 8-12 mm. broad; outer 

 bracts of the involucre ovate to lanceolate, obtuse or acutish, 4-6 mm. long; 

 achenes 3-angled, obovoid, obcompressed, 3-ribbed. In damp, rich shaded places, 

 western Ont. to Minn., Ga., Mo. and Ark. June Sept. 



Polymnia Canadensis radiita A. Gray. Ligules larger, sometimes 12 mm. long, 

 3-lobed, nearly white. Occasional in the range of the type. 



49. MELAMPODIUM L. 



Herbs, some species woody, with opposite entire or dentate leaves, and ter- 

 minal peduncled heads of both tubular and radiate, white or yellow flowers in our 

 species. Involucre hemispheric, its bracts in 2 series, the 4 or 5 outer ones broad, 

 often connate at the base, the inner hooded, embracing or permanently surrounding 

 the pistillate fertile ray-flowers. Receptacle convex or conic, chaffy. Ray-flowers 

 in i series, the rays spreading, 2-3-lobed or entire. Disk-flowers perfect, sterile, 

 their corollas with a narrowly campanulate 5-toothed limb, the anthers entire at 

 the base, the style undivided. Achenes obovoid, more or less incurved. Pappus 

 none. [Greek, black-foot, without significance.] About 25 species, natives of 

 the warmer parts of America. Besides the following, some 4 others occur in the 

 southwestern U. S. 



i. Melampodium leucanthum T. & G. PALE MELAMPODIUM. (I. F. f. 

 3864 as M. cinereum,} Perennial, canescent, 1-3 cm. high, the branches slender. 

 Leaves linear, lanceolate, or the lower spatulate, sessile, entire, undulate or sinu- 

 ate, 3-5 cm. long, 3-9 mm. wide, obtuse or obtusish at the apex; heads 16-28 mm. 

 broad; peduncles slender, 2-7 cm. long ; outer bracts of the involucre ovate or 

 oval, obtuse, united below; rays 5-9, cuneate -oblong, white; inner bracts turbinate 

 or terete, hooded, muricate, the hood wider than the body. In dry soil, Kans. to 

 Colo., Ariz., Tex. and Mex. June-Oct. 



50. SILPHIUM L. 



Tall perennial herbs, with resinous juice, and large corymbose or paniculate 

 (rarely solitary) peduncled heads of both tubular and radiate yellow flowers. In- 

 volucre hemispheric or campanulate, its bracts imbricated in few series. Receptacle 

 flat or nearly so, chaffy, the chaff subtending the disk-flowers. Ray-flowers in 2 

 or 3 series, pistillate, fertile, the ligules numerous, linear. Disk-flowers perfect 

 but sterile, their corollas tubular, 5-toothed. the style undivided. Anthers min- 

 utely 2-toothed or entire at the base. Achenes broad, dorsally flattened, 2-winged, 

 notched at the apex. Pappus none, or of 2 awns confluent with the wings of the 

 achene. [Greek, from the resinous juice.] About 25 species, of N. Am. 



Stem leafy, the leaves opposite, alternate, or verticillate. 



Leaves, or their petiole-bases, connate-perfoliate ; stem square. 



1. S. perfoliatum. 

 Leaves not connate-perfoliate, sessile or petioled. 



Leaves opposite, or the uppermost alternate; cauline sessile. 



2. S. integrifolium 

 Leaves, or some of them, verticillate in 3's or 4% petioled. 



3. S. trifoliatunt. 

 Most or all of the leaves alternate, entire or dentate. 



Involucral bracts ovate to orbicular, mostly obtuse, glabrous or puberulent. 



4. S. Asteriscus. 

 Involucral bracts triangular to lanceolate, acute, hirsute or pubescent. 



5. S. Gatesii. 

 Leaves all alternate, pinnatifid or bipinnatifid, large. 6. S. laciniatum. 



Stem leafless or nearly so, scaly above; leaves basal, large. 7. S. terebinthinacciim. 



