284 PRACTICAL BOTANY. 



983. Achenia winged and sometimes also 2-toothed, 

 Heads corymbed, or nearly solitary. Tall rough herbs. 

 Lower leaves sometimes whorl ed in threes. Silphium. 



Achenia flattened. Heads always single, long- 

 peduncled. A hairy, low herb (2-G inches high). Flowers 

 yellow. Leaves ovate or spatulate, crenate, long-petioled. 

 Chrysogonum Virginianum, L. 



084. Achenia compressed laterally, or not at all 086 



Achenia compressed back and front 985 



98«>. Achenia with upwardly barbed awns, or awnless, 

 never beaked. Hays yellow, or partly colored, rarely 

 purple. Coreopsis. 



{Tlckseecl) 



Achenia with retrorsely hispid awns, often attenu- 

 ated above. Bidens. 



(Bur-Marigold. ) 



086. Achenia wingless. Awns deciduous. Heads soli- 

 tary or corymbed. (980) Helianthus. 

 Achenia broadly winged. Awns persistent. 



(980) Actinoiueris. 



98?. (904.) Pappus present 988 



Pappus none. Involucre cylindric, of. 8 scales, in 

 a single row, 8- to 12-flowered. Heads small, loosely pani- 

 cled; flowers yellow. Leaves angled, or toothed, ovate, or 

 sometimes lyre-shaped. Lampsana communis, L. 



{Nipple-ioort^ 



988. Pappus of plumose bristles, which are chafiy- 

 dilated at the base, either on a short beak, or sessile. Scapes 

 bearing one or more yellow heads. The radical leaves pin- 

 natifid. Leontodon autumnale, L. 



Pappus not plumose 989 



989. Pappus chaff'y, or of both chaff and bristles. . .990 

 Pappus composed exclusively of capillary bristles. 



992 



990. Rays yellow. Pappus double. Heads terminating 

 the naked scapes, or branches. Leaves chiefly radical. . .991 



Rays blue. Pappus a small crown of little, bristle- 

 form scales. Involucre double. Heads large, 2 or 3 together, 



