Blepharipappus. COMPOSITE. 357 



53. BIDENS, Linn. BUR-MARIGOLD. 



Head many-flowered, heterogamous and the 3 to 10 rays neutral, or homogamous 

 and the flowers all perfect and tubular. Involucre double ; the outer of a few mostly 

 foliaceous loose or spreading scales ; the inner of several erect and more membrana- 

 ceous scales. Eeceptacle flat or convex ; the thin narrow chaff deciduous with the 

 fruit. Akenes obcompressed, either broad and very flat or narrow, beakless, bearing 

 a pappus of 2 to 4 rigid and retrorsely barbed awns. Annual or perennial herbs ; 

 with opposite leaves, and small or middle-sized heads of yellow or sometimes white 

 flowers; some of them vile weeds. The species are numerous, and very widely 

 distributed over the world, but there are remarkably few in California or in the 

 Pacific region. 



* Akenes broad : leaves merely serrate. 



1. B. chrysanthemoid.es, Michx. Annual, glabrous, leafy to the top, a foot or 

 two high : leaves broadly lanceolate, tapering to both ends, closely sessile, serrate, 

 3 to 5 inches long : heads rather large and showy : scales of inner involucre broad : 

 rays 8 to 10, golden yellow, oblong or oval, an inch long: akenes wedge-shaped ; 

 their margins and the 2 to 4 rather long awns barbed with rigid or almost prickly 

 reflexed bristles. 



Wet places, apparently not rare through the western part of the State. Extends to Mexico, 

 and is common in all the Atlantic States. 



B. CERNUA, Linn. , a tall variety of which grows in Oregon, has smaller leaves, heads without 

 rays, or with short ones of lighter yellow, and smaller barbs to the akene and awns. The two per- 

 haps run together. The plant named B. cernua by Hooker and Arnott, in the Botany of Beechey's 

 Voyage, is probably the preceding. 



% * Akenes long and narrow (Spanish Needles] : leaves divided or compound. 



2. B. pilosa, Linn. Annual, more or less hairy, or merely the leaves sparsely 

 pubescent : these 3-parted or the lower 5-parted into ovate incisely cleft or sharply 

 serrate thin leaflets : heads small, without rays or with 2 or 3 small and whitish 

 ones : akenes linear, smooth, or the outer ones upwardly hispid-scabrous, at least 

 towards the summit, 2 - 4-awned. B. Californica, DC. Prodr. v. 599. Torr. & 

 Gray, Fl. ii. 354. 



Santa Barbara to Los Angeles, near water-courses, &c. A weed, widely diffused over the 

 warmer coasts, especially of the Pacific : if correctly indentified with B. pilosa, doubtless intro- 

 duced with cattle into California. 



HETEROSPERMUM XANTI, Gray, of Lower California, resembles a Bidens with finely divided 

 leaves, and is intermediate between the two genera. 



54. BLEPHARIPAPPUS, Hook., Torr. & Gray. 



Head heterogamous, with 3 to 6 pistillate rays : disk-flowers 7 to 12 perfect, some 

 of the central infertile. Scales of the involucre 6 to 10, nearly in a single series, 

 lanceolate, erect, almost equal. Receptacle convex, chaffy; the chaff thin and 

 menibranaceous, deciduous with the fruit. Eays short and broad, cuneiform, 3- 

 lobed. Style in the disk-flowers long, thickened upwards and hairy, 2-cleft only at 

 the apex (the branches obtuse and not appendaged), or in the central and sterile 

 flowers nearly entire. Akeues turbinate, silky- villous. Pappus of 10 or 12 linear 

 hyaline scales, traversed by a stout awn-like midrib, the margins lacerately fringed 

 so as to appear plumose, rarely wanting. Annual, corymbosely or paniculately 

 branched ; both rays and disk-corollas white ; the anthers brown-purple. Only 

 one variable species. 



