KEY. 283 



Heads white-flowered ; rays 5 only, their ligules 

 very short and broad, inversely heart-shaped, not project- 

 ing beyond the woolly disk. Pappus of 2 chaffy scales. 

 Heads small, in a dense, flat corymb. Leaves oblong, or 

 ovate, crenate-toothed. Parthenium integrifolium, L. 



976. Rays yellow 978 



Rays white or purple 977 



977. Rays white, spreading. Pappus none. Recep- 

 tacle chaffy only at the summit ; the chaff deciduous. 

 Leaves finely thrice-pinnately divided. Branches termina- 

 ted by single heads ; rays at length reflexed. Involucral 

 scales white-margined. Maruta Cotula, D. C. 



Rays purple, drooping. Chaffy scales sharply 

 pointed, elongated. Disk purplish. Head solitary, showy, 

 at the summit of the stem. Leaves serrate, or entire, 3- to 

 5-uerved (sometimes bristly-hairy). Echinacea. 



978. Pappus of 2 awns 980 



Pappus none 979 



979. Achenia 4-cornered, flat at the top. Rays generally 

 drooping. Heads showy, terminating the stem and branches. 

 Bisk greenish-yellow, or dark j)iirple, sometimes columnar. 



Rudbeckia. 



Achenia compressed laterally and margined. Rays 



few, large (2 inches long), drooping. Disk grayish. Leaves 



pinnate, of 3-7 leaflets. Heads single, showy, at the end of 



the branches. Lepachys pinnata, Torr. & Gr. 



980. Achenia broadly winged. Awns persistent. Heads 

 corymbed. Leaves serrate, feather-veined, tapering to the 

 base and mostly decurrent on the stem. 



Actinomeris (980). 

 Achenia wingless. Awns deciduous. Heads soli- 

 tary, or corymbed. Helianthus (986). 



981. (973.) Disk-flowers fertile; rays sterile; achenia 

 with awns 984 



Disk-flowers sterile ; rays fertile 982 



98S, Pappus 2- or 3-toothed 983 



Pappus none. Heads in panicled corymbs; flow- 

 ers light yellow. Leaves large, thin, lobed, and with siipule- 

 like appendages at the base. Folymnia. 



