COMPOSITE FAMILY. 183 



13. BI'DENS, L. BUR-MARIGOLD. 



[Latin, Si-dens, having 2 teeth ; in allusion to the awns of the akenes.] 



Heads inany-flowered ; ray-Jlorets neutral, often inconspicuous and some- 

 times wanting, those of the disk tubular and perfect. Involucre 

 double, the outer scales larger and often foliaceous. Receptacle fiat- 

 tish, the chaff deciduous with the fruit. Akenes flattened, or slender 

 and more or less 4-sided, crowned with two or more retrorsely hispid 

 awns. Annual or sometimes perennial herbs. Leaves opposite, incised- 

 serrate or pinnatifidly dissected. Flowers mostly yellow. 

 * Akenes fiat and broadish, not beaked at summit, ciliate on the margins. 



1. B. frpndo'sa, L. Leaves odd-pinnately divided, the lower ones 

 with 5 divisions, the upper with 3 ; divisions distinct and mostly peti- 

 olulate, lanceolate, serrate ; heads discoid, on slender axillary peduncles ; 

 outer scales of the involucre foliaceous, narrowed and ciliate at base, 

 much longer than the head ; akenes obovate-cuneate, 2-awned, pubescent 

 and ciliate with erect hairs. 



FROXDOSE BIDEXS. Bur-marigold. 



Root annual. Stem 2-4 or 5 feet high, somewhat hairy, often dark purple, branched. 

 Leaflets or segments 2-4 or 5 inches long, pilose beneath, abruptly narrowed at base to a 

 short margined ciliate petiolule, the common petiole 1-3 inches long. Heads rather small , 

 on long slender naked peduncles. Involucre double, the 8-10 outer scales lanceolate, 

 leaf-like, unequal, 2 or 3 - 5 or 6 times as long as the head, ovate-lanceolate, with a scarious 

 margin. Florets yellowish. Chaff of the receptacle linear-lanceolate, about as long as 

 the akenes. 



Gardens, fence-rows, Indian-corn fields, &c. : throughout the United States. Fl. Au- 

 gust-September. Fr. October. 



Obs. All the species, here enumerated, are very worthless, and par- 

 ticularly disagreeable weeds, on account of the barbed awns of the 

 fruit, which cause it to adhere in great numbers to clothing. This one 

 is apt to be quite abundant in gardens, Indian-corn fields, &c. and if 

 permitted to mature its fruit, becomes very annoying, in the latter part 

 of6ummer. 



2, B. chrysanthemoi'des, MX. Leaves oblong-lanceolate, tapering 

 at each end, serrate, sessile, and connate at base ; heads conspicuously 

 radiate, often somewhat nodding ; outer scales of the involucre foliaceous, 

 mostly shorter than the rays ; akenes oblong-cuueate, 2 - 4-awned, re- 

 trorsely aculeate-ciliate on the margins. 



CHRYSAXTHEMUM-LIKE BIDEXS. Beggar-ticks. 



Plant glabrous. Root annual. Stem 6 inches to 2 feet high, erect or often declined at 

 base, branching, the branches opposite and axillary. Leaves 3-6 inches long. Heads 

 rather large, solitary, terminating the branches. Outer scales of the involucre about 8, 

 linear-lanceolate, ciliate-serrulate, spreading, the largest sometimes nearly as long as tho 

 rays ; the inner scales membrauaceous, elliptic or ovate-oblong, nearly equal, about as 

 long as the disk-florets. JBaj/sbright yellow, numerous, near an inch long. Akenes striate- 

 ribbed and somewhat keeled on the flatted sides ; awns usually 4. Chaff of the receptacle 

 spatulate-liuear, scarious, 3-nerved, yellow, or sometimes purplish at summit. 



Low grounds, along swampy rivulets : generally throughout the United States. Fl. 

 August -September. Fr. October. 



Obs. This species is rather showy, when in flower, and is less inclined 

 than either the preceding or the following to invade cultivated grounds 



