246 KEY AND FLORA 



at the apex ; chaff as long as the flowers. Akenes oblong, the wings 

 narrow and thickened ; pappus of 2 minute teeth. In rich woods.* 



5. C. palmata Nutt. Stiff Tickseed. Perennial ; stem stiff, 

 smooth, little or not at all branched, very leafy, 1-3 ft. high. Leaves 

 3 -cleft, broadly wedge-shaped, stiff ; the lobes linear-oblong, middle 

 one often 3-lobed. Heads on short peduncles, few or solitary, 1^-2 in. 

 in diameter; bracts of the outer series narrower than the inner ones, 

 slightly shorter. Rays 6-10, bright yellow, broad, usually o-toothed. 

 Akenes oblong, with narrow wings. Dry prairies and thickets W. 



6. C. verticillata L. Perennial ; stem smooth, stiff, slender, branch- 

 ing freely, leafy, 1-2 ft. high. Leaves divided into 3 sessile leaflets, 

 the latter once or twice pinnately parted into narrowly linear or thread- 

 like divisions. Heads li-li in. in diameter; outer bracts much nar- 

 rower than the inner ones. Rays 6-10, yellow. Akenes oblong, with 

 narrow wings. In dry or moist soil, sometimes cultivated. 



VII. HELENIUM L. 



Annual or perennial. Leaves alternate, forming wings on 

 the stem. Heads radiate, peduncled, many-flowered; bracts in 

 2 series, the outer linear and spreading, the inner few and 

 scale-like ; receptacle naked, convex or oblong. Ray flowers pis- 

 tillate and fertile, or neutral, the rays w^edge-shaped, 3-5-lobed; 

 disk flowers bisexual, tubular, 4-5-lobed. Akenes top-shaped, 

 hairy, ribbed ; pappus of 4-5 entire, toothed or awned scales.* 



1. H. nudiflorum Nutt. Sneezeweed. Perennial; stem slender, 

 erect, downy, branched above, 1-2 ft. high. Leaves lanceolate, entire 

 or slightly toothed, the lower petioled, the upper sessile. Heads nu- 

 merous. Ray flowers 10-15, neutral, yellow or yellow and brown; 

 disk flowers purple. Akenes hairy on the ribs ; pappus of ovate, 

 minutely toothed, awned scales. Common on river banks S.* 



VIII. ACHILLEA L. 



Perennial. Leaves alternate, pinnately divided. Heads with 

 ray flowers in a terminal corymb ; involucral bracts imbricated 

 in several series, the outer shorter ; receptacle chaffy. Eay 

 flowers white or pink, pistillate and fertile ; disk flowers bi- 

 sexual, tubular, 5-lobed. Akenes oblong, compressed, slightly 

 margined ; pappus none.* 



1. A. Millefolium L. Yarrow. Stems often clustered, erect from 

 a creeping rootstock, simple, downy or woolly, 1-2 ft. high. Leaves 



