87 



Fig. 69. Cenchrus tribuloides L. Sand Bir. — An annual, 

 with spreading or ascending, much-branched, compressed culms 

 usually about 3 dm. high, and terminal racemes, of 6 to 20 bur- 

 like involucres. — Sandy fields, waste ground, river banks, and sea 

 beaches, Maine and Ontario to South Dakota and Colorado, south 

 to Florida and southern California. [Mexico and South America.] 

 June-October. 



