402 



CAKDUACEAE. 



1. Bidens pilosa L. WHITE BEGGAR-TICKS. 

 (Fig. 442.) Annual, glabrous or somewhat 

 pubescent, l-3 high, more or less branched. 

 Leaves petioled, 3-divided, their segments ovate 

 to lanceolate, l'-3i' long, serrate, acute or 

 acuminate, the uppermost sometimes undivided; 

 involucre campanulate, about 4" high, its outer 

 bracts linear-oblong, usually shorter than the 

 inner; rays, when present, white, 5" 10" long. 

 2-3-lobed ; achenes fusiform, unequal, the inner 

 longer than the involucre ; pappus of 2-4 yel- 

 low downwardly barbed awns. [B. leucantha 

 Willd.] 



Common in waste and cultivated ground. 

 Naturalized. Native of tropical America. Both 

 radiate and rayless races occur. Flowers in sum- 

 mer and autumn. 



17. GAIINSOGA E. & P. 



Annual branching herbs, with opposite 

 leaves, and small peduncled heads of both 

 tubular and radiate flowers, terminal and in 

 the upper axils. Involucre hemispheric or campanulate, its bracts in 2 series, 

 ovate, obtuse, membranous, striate. Eeceptacle conie or elongated, its thin 

 chaff subtending the disk-flowers. Ray-flowers white, pistillate, fertile, the 

 rays 4 or 5, short. Disk-flowers yellow, perfect, the corolla 5-toothed. Anthers 

 minutely sagittate at the base. Style-branches tipped with acute appendages. 

 Achenes angled, or the outer ones flat. Pappus of the disk-flowers of several 

 short laciniate or fimbriate scales, that of the ray-flowers of several or few 

 short slender bristles, or none. [Named in honor of M. M. Galinsoga, super- 

 intendent of the Botanic Gardens at Madrid.] About 5 species, natives of 

 tropical and warm temperate America, the following typical. 



1. Galinsoga parviflora Cav. GALIN- 

 SOGA. (Fig. 443.) Slightly appressed- 

 pubescent, l-3 high. Leaves thin, 

 ovate or deltoid-ovate, 3-nerved, f'-3$' 

 long, acute at the apex, mostly obtuse 

 at the base, dentate, the lower slender- 

 petioled, the upper short-petioled or 

 sessile, and sometimes nearly or quite 

 entire; heads usually numerous, 2"-3" 

 broad, slender-peduncled ; bracts of the 

 involucre glabrous or nearly so, the outer 

 shorter; pappus of the disk-flowers 4-16, 

 oblong to spatulate, fimbriate obtusish 

 scales, shorter than the finely pubescent 

 obpyramidal achene. 



Cultivated grounds, occasional or fre- 

 quent ; first introduced in the Agricultural 

 Gardens in 1008. Naturalized. Native of 

 tropical America. Widely naturalized in 

 the United States. Flowers In summer and 

 autumn, probably also earlier. 



