404 COMPOSITAE. 



perfect, often staminate or pistillate. Heads with both ray- and disk- 

 llowcrs are called radiate; with disk-flowers only, discoid. Calyx-tube united 

 with the ovary, the limb when present called a pappus and greatly varied in 

 structure, consisting of awns, hairs, bristles, scales or paleae, or in many cases 

 appearing as a more crown or ring or wholly obsolete. Stamens 5; filaments 

 tree; anthers united and forming a tube, or nearly or quite free in the tribe of 

 Ambrosieae. Style divided above into 2 long branches which bear stigmatic 

 lines on the inside. Ovary 1-celled, 1-ovuled, maturing into an achene, crowned 

 by the pappus when that is present. Pappus commonly persistent and assist- 

 ing in the dispersion of the 1-seeded fruit. 



KEY TO THE TRIBES. 



Heads composed wholly of perfect flowers with ligulate corollas; ligule 5-toothed at apex; 



herbs with milky juice; leaves alternate or radical 1. Cichorieae. 



Heads composed of ray- and of disk-flowers or of disk-flowers only. 



Receptacle covered with bristles; heads large; flowers conspicuous; corollas cleft into 

 long narrow lobes; rays none; very spiny thistles or thistle-like plants; leaves 



alternate 2. Cynareae. 



Receptacle with chaffy bracts (see also nos. 28 and 29). 



Rays always present, conspicuous or inconspicuous; disk-flowers perfect; bracts of 

 the involucre foliaceous or herbaceous, not scarious; pappus of paleae or awns, 

 never capillary. 

 Involucre of 1 series of equal bracts, each embracing or enfolding a ray-achene; 

 bracts of receptacle often in a single series between ray and disk; leaves alter- 

 nate or opposite; (annuals except two) 6. Madieae. 



Involucre of 1 to several series of bracts, none enfolding ray-achenes; receptacle 



very chaffy; leaves mostly opposite or radical 7. Heliantheae. 



Rays none; leaves alternate (except no. 69). 



Heads unisexual (except no. 63), small, greenish or white; corolla of pistillate 

 flowers none or a rudiment; anthers nearly or quite distinct; pappus none; 



fruit usually a bur; leaves alternate (the lower opposite in no. 63) 



8. Ambrosieae. 

 Heads composed of both pistillate and staminate (or perfect) flowers; corolla of 

 pistillate flowers filiform; bracts of the involucre few or none; leaves alter- 

 nate (except no. 69) ; white-woolly annuals 9. Inuleae. 



Receptacle naked (without bristles or chaffy bracts, except nos. 28 and 29); leaves 

 alternate (except nos. 26, 36, 37, 38, and 91). 

 Bracts of involucre in 1 or 2 series; pappus of soft capillary bristles; both disk- and 



ray-flowers yellow (except no. 23) 3. Senecioneae. 



Bracts of involucre imbricated, dry and scarious; pappus none or reduced to a mere 

 crown or ring; flowers white, yellow or greenish; rays present or absent; leaves 



usually much divided 4. Anthemideak. 



Bracts of involucre in few series, little imbricated; pappus paleaceous, awn like, 

 bristly or none; flowers yellow; rays present (except in no. 42) ....5. Helenieae. 

 Bracts of the involucre many and imbricated, often dry or scarious; pappus of cap- 

 illary bristles; rays none; pistillate corollas mostly filiform; (pappus none and 



bracts few in no. 75) 9. Inuleae. 



Bracts of involucre well imbricated; disk-flowers commonly yellow, the rays of the 

 same or different color or none; pappus of awns or bristles (or of short scales 



in no. 76) 10. Astereae. 



Bracts of the involucre equal or imbricated; flowers perfect, white or whitish; rays 

 none 11. Eupatorieae. 



Tribe 1. Cichorieae. Chicory Tribe. 



Serbs with milky juice and alternate or radical leaves. Eeceptacle naked 

 or with chaff-like bracts. Flowers all perfect and all with ligulate corolla, 

 the ligule 5-toothed at apex. Anthers sagittate or auricled at base, commonly 

 appendaged at summit. Style-branches stigmatic on their inner side for their 



whole length. 



./. Pappus paleaceous or of rigid bristles. 

 Pappus paleaceous, the paleae without awns; achenes neither ribbed nor beaked. 

 Flowers blue; receptacle naked; herbage soft 1. Cichorium, 



