MONOCOTYLEDONES 



313 



roots are fibrous, the stems hollow ai^d closed at the nodes, the 

 leaf of the typical grain type, the inflorescence of spikelets ar- 

 ranged on a spike, which is frequently referred to as the head. 

 The axis or rachis of the spike is zigzag, the spikelet being at- 

 tached on the outer or convex side of the curve and resting in the 

 concave side next above. Each spikelet contains from two to 

 five flowers, but usually only two grains reach maturity. Each 



F 



FIG. 154. Six types of wheat. Top row, durum. Polish wheat, and white winter. Bottom 

 row, red winter, hard winter, and hard spring. (Productive Farm Crops.) 



flower consists of one pistil, with two stigmas, three stamens and 

 two glumes (the outer or lemma and the inner or palet}. The 

 entire spikelet is enclosed between two glumes. The lemma and 

 the palet are sometimes spoken of as fertile glumes and the two 

 outside glumes as empty glumes. 



History. Wheat has been cultivated from a very remote 

 period and is generally supposed to have originated in western 



