DEVELOPMENT OF PLANTS 



373 



also of the greatest economic importance, furnishing a variety 

 of foods, as wheat, rye, barley, oats, rice, corn, hay, etc. The 

 bamboo also belongs to the order. The stem in the majority 

 of forms is a rhizome (as in Typha), which branches extensively 

 through the soil and sends up numerous aerial branches (Fig. 282, 





FIG. 282. Habit of growth of one of the grasses : A, aerial stem termi- 

 nating in a branched inflorescence. B, underground stem or rhizome send- 

 ing up a new shoot from one of the nodes. C, section through the node 

 of a stem that has been placed horizontal, showing the sheathing leaf base, 

 /, and the beginning of the upward curvature of the stem. 



B). These interwoven rhizomes, with their numerous roots, form 

 the firm swards of meadows and prairies. The aerial stems are 

 models of mechanical construction. The ability of the long 

 hollow stems of the grasses to support the heavy head of grain 

 must appeal to every one. An examination of Fig. 282 will 

 show you how the stem is reinforced by the long sheathing base 

 of the leaves while tough, elastic strands of stereome fibers are 

 so distributed as to give the best mechanical support. An un- 



