THE FLOWER 141 



The leaf-sheaths are green and their swollen nodal portions plump 

 and sappy. 



The glumes and pericarp of the grain are also green, the chlorophyllous 

 layer of the latter showing through the outer colourless tissue. 



At this stage the grain has attained its maximum volume and highest 

 water content ; the vacuoles of the endosperm tissue contain watery sap, 

 and starch grains are abundant in the cells ; from it can be squeezed a 

 milk-like liquid whose whiteness is due to numerous starch grains present 

 in it. 



The several parts of the embryo are completely differentiated, but 

 have not quite reached their full development, and although grains 

 harvested now germinate readily, the young plants are somewhat weak. 



In the yellow-ripe stage the crop has changed to a golden tint except 

 in the purple-strawed forms which are a pinkish purple colour. The 

 straw is smooth and shining, tough and pliable. 



The chlorophyll has disappeared from all parts of the leaves, except 

 the thick nodal portions of the upper leaf-sheaths, which still remain 

 swollen and green, those of the lower leaf-sheath being shrunken and 

 brownish. 



The glumes have assumed their characteristic ripe tint. 



As ripening proceeds, the chlorophyll in the pericarp of the grain 

 gradually disappears, first from the upper part and dorsal side, and later, 

 from the lower part and the furrow ; in the yellow-ripe stage it is no longer 

 to be seen. 



The grain can be crushed between the thumb and finger-nail, the 

 contents, however, are not milky, but soft, and they knead like dough. 



This is the best stage of ripeness in which a crop of wheat should be 

 cut ; assimilation is at an end, and there is no gain in weight by leaving 

 it longer. The danger of losing some of the grain by " shattering " is 

 also reduced by harvesting at this period of development. 



The ripe stage is reached in dry, clear weather thpee or four days after 

 the yellow-ripe stage. The thick basal portions of the leaf-sheaths are 

 now dry and shrunken. 



The grain readily parts from the rachilla and is liable to shake out of 

 the glumes. It is firm, and though it may be dented by pressure of the 

 thumb-nail, it is not easily crushed. Its characteristic colour has become 

 more distinct, the yellow grains paler, the red grains somewhat darker, 

 and the flinty or mealy character of the endosperm is clearly emphasised. 



In the dead-ripe stage the straw becomes dull, more and more brittle 

 and dirty the longer it is left uncut. 



The axis of the ear is liable to become brittle and in some forms the 

 ears fall off or break in pieces ; the grain " shatters " easily, and much is 

 lost in harvesting the crop if left as late as this. 



