[Chap. LI SOME FAMILIES OF FLOWERING PLANTS 



695 



Fig. 332. Two important grasses of the western plains: blue grama (left) and 

 buffalo grass (right) in bloom. Photos from U. S. Soil Conservation Service and 

 F. H. Norris. 



and pans, household utensils and agricultural implements, musical 

 instruments and umbrellas, paper and mattresses, and as food and 

 medicine. 



The plants of the grass famil)- are mostly herbs, although woody bam- 

 boos may be trees of considerable size. Wild grasses are distributed 

 throughout the world, and are the dominant plants on the steppes, 

 plains (Fig. 332), and prairies of all the continents. They occur from 

 sea level to alpine heights, in shallow water and in the desert, in the 

 open as well as in the shade, and on both acid and alkaline soils. The 

 cultivated grasses — corn, wheat, rye, barley, oats, rice, sorghum (Fig. 

 333), sugar cane — also cover an enormous acreage throughout the 

 world. There are some 5000 described species of grasses, and the num- 

 ber of individuals doubtless surpasses that of all other cultivated plants 

 put together. 



The grass flower and its associated parts are highly specialized ( Figs. 

 334 and 155). The unit flower cluster is the spikelet, made up of two 

 or more flowers enclosed by bracts, called empty glumes. Each flower 

 is also enclosed in two flowering glumes. Only remnants of a perianth 



