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 abimdant milky juice.) 



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

 leaves not prickly on the mid-veins beneath. W. C. E. L. splcata 



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 12-20-flowered; akenes i-veined on each face. W. — Cultivated for 

 eating. L. sativa (garden lettuce) 



DD. Heads 6-1 2-flowered; akenes several-veined on each face; plant 1-4 m. high, 

 E. Leaves strictly entire. E. L. sagittifoUa 



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. vlrens (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. 



