The Origin of Wheat. 165 



degraded kinds they are often wholly wanting, having 

 been quite crushed out between the calyx and the 

 grain. It is only the larger and more primitive types 

 that still exhibit them in any great perfection. On 

 the other hand, one group of very large exotic grasses, 

 the bamboos, has three regular petals, thus clearly 

 showing the descent of the family as a whole from 

 rush-like ancestors, and also obviously suggesting 

 that the obsolescence of the inner petal in the other 

 grasses is due to their small size and their closely 

 packed minute flowers. 



Among the stamens, one-sidedness has not notably 

 established itself, for in wind-fertilised plants they 

 must necessarily hang out freely to the breeze, and 

 therefore they do not get much crowded between the 

 other parts. A few grasses still even retain their 

 double row of stamens, having six to each floret ; but 

 most of them have only one whorl of three. In some 

 of the lower and more degraded forms, however, even 

 the stamens have lost their trinary order, and only 

 two now survive. This >is the case in our own very 

 degenerate little sweet-vernal-grass, the plant which 

 imparts its delicious fragrance to new-mown hay. 

 But in the cereals and in most other large species the 

 three stamens still remain in undiminished effective- 

 ness to the present day. 



