94 BOTANY OF CROP PLANTS 



a.m., there is less blooming; this is followed by a period from 

 9:00 a.m. to 10:00 a.m. of more rapid blooming, which in 

 turn is followed by an interval of less rapid rate up to 2 -.^o 

 p.m.; after this there is an increase in the rate again until 

 3:30 p.m., and from this hOur up to 7:00 p.m., only a slight 

 amount of blooming takes place. Fluctuation in the time 

 of blooming is less noticeable in einkorn than in other wheats, 

 and less marked on sultry days following rainy days in all 

 types of wheat. Polish wheat shows the most marked 

 fluctuations. Temperature and moisture are certainly the 

 important external factors determining the time of blooming. 

 There appears to be considerable variation even in the same 

 variety. 



It is stated that the swelling of the lodicules brings about 

 the separation of the lemma and palet and hence the open- 

 ing of the flower. Grass flowers in which the lodicules are 

 membranous or wanting remain closed, while those in which 

 there is only slight swelling of the lodicules open but to a 

 small extent. 



In the unopened wheat flower, the filaments are short, 

 the stigmas erect and in contact. The palet and lemma 

 separate, first slowly and then quickly. The filaments 

 then elongate rapidly, pushing the anthers up and outside 

 of the glumes. The anthers are shedding pollen before the 

 flower is fully open, and they continue to do so until it closes 

 again. All three anthers do not always protrude from the 

 flower, and, in some instances, none may escape before 

 the flower closes. The first flowers to open are those situated 

 about one-third of the way from the tip of the spike. The 

 others follow in succession above and below this point. 

 Each flower remains open from a half hour to one hour. 

 The head^completes its flowering usually in several days. 



In northern cold or wet climates, close poUination {auto- 



