238 COMPOSITACEAE (COMPOSITE FAMILY) 



LACTUCA (LETTUCE) 



Stems tall, leafy. Heads in panicles ; receptacle naked. Corolla yellow 

 or blue or purple. Pappus-bristles capillary, soft, many. (L. lac = milk ; 

 from the abundant milky juice.) 



A. Pappus brownish; flowers blue; plant 1-3.5 m. high; involucre 10-12 mm. long; 

 leaves not prickly on the mid-veins beneath. VV. C. E. L. spicata 



AA. Pappus white; flowers rarely blue, mostly yellow. 

 B. Leaves not prickly on the mid-veins beneath. 



C. Flowers blue; perennial; involucre 16-20 mm. long; akene and its beak about 



as long as the pappus. W. E. L. pulchella (BLUE LETTUCE) 



CC. Flowers yellow, rarely purplish; annual or biennial; involucre 8-14 mm. long; 



akene and its beak about as long as the pappus. 



D. Heads 1 2-20-80 wered; akenes i -veined on each face. W. Cultivated for 



eating. L. sativa (GARDEN LETTUCE) 



DD. Heads 6- 12 -flowered; akenes several-veined on each face; plant 1-4 m. high. 



E. Leaves strictly entire. E. L. saglttifolia 



EE. Leaves except the upper ones sinuate-pinnatifid. E. 



L. canadensis (WILD LETTUCE) 



BB. Leaves prickly on the mid-veins beneath; flowers yellow; akene about equaling 

 its beak. W. E. A bad weed of waste places. Sometimes called China Lettuce. 



L. scariola (PRICKLY LETTUCE) 



CREPIS (HAWK'S-BEARD) 



Stems leafy or scapelike. Corolla yellow. Pappus bristles capillary, 

 many, usually soft. (Gk. krepis = a sandal. Application not clear.) 



A. Leaves glabrous, some of them pinnatifid; stem leafy; stem leaves clasping. W. E. 



C. virens (SMOOTH HAWK'S-BEARD) 

 AA. Not as above in all points. Too difficult for beginners. 



HIERACIUM (HAWKWEED) 



Perennial. Leaves sometimes all basal. Corolla white or yellow. Pap- 

 pus of capillary bristles, scabrous. (Gk. hierax = a hawk ; it was supposed 

 to better the vision of birds of prey.) 



A. Flowers white; involucre not distinctly imbricated. W. C. E. 



H. albiflorum (WHITE HAWKWEED) 

 AA. Flowers yellow. Too difficult for beginners. 



