75 



Fig. C9. CENCHRTJS TRIBULOIDES L. Sp. PI. 1050. 1753. SAND BUR.— Au 

 annual with spreading or ascending, much branched, compressed cuhiis about 

 3 dm. (1°) high, and terminal spikes of 6-20 burs inclosing the spikelets. Burs 

 (a) nearly globose and covered with strong and more or less pubescent, barbed 

 spines, becoming very hard at maturity, inclosing two spikelets. Spikelets (e) 

 two-flowered, about 6 mm. (3") long; glumes thin, membranaceous.— Sandy 

 fields, waste grounds, river banks, and sea beaches. Maine and Ontario to South 

 Dakota and Colorado, south to Florida and southern California. (Mexico and. 

 South America.) June to October. 



One of the worst of annual weeds wherever it becomes abundant. 



