THE STEMS 91 



ing winter, sending up their stems and ears in the following year very 

 little in advance of plants sown several months later. 



The critical period is nearly constant for the same form ; there is 

 indeed a certain degree of irregularity in the development of the plants 

 sown about this date, some individuals sending up a few ears, while others 

 refuse to do so entirely ; sown a week earlier or later, however, the plants 

 exhibit a decision in their behaviour which is very striking. 



For a time the young plants in successive rows grow and develop 

 apparently at the same rate, but ultimately the earlier sown rows send up 

 their stems and ears to a height of 3-4 feet, the neighbouring rows in which 

 the sowing has been delayed but a week or ten days remaining a few inches 

 high ; the contrast is remarkable in view of the small difference of time 

 between the sowings and the apparently similar climatic conditions under 

 which the plants are grown. 



Fife wheat sown before the critical period say in May produces 

 ears in 60-70 days, whereas it does not come into ear until about 300 

 days have passed when sown at the end of July or beginning of August. 

 Similarly, later wheats may produce ears in 115-120 days, or not before 

 the lapse of 400 days according to the time of sowing. 



Fife wheat sown on May 10, 1913, was in ear in 54 days, i.e. on July 13. 



The late form, Dawson's Golden Chaff, came into ear most rapidly 

 when sown in March, the time between sowing and " earing " being 116 

 days. 



When sown at the most favourable time certain wheats come into ear 

 in 6 or 7 weeks, but forms with such power of rapid development are rare. 

 A Chinese wheat from Newchwang sown on May 25, 1911, was fully in 

 ear on July 8, or 44 days after sowing, and another from Fu-chia Chuang 

 sown on May 18, 1916, came into ear on July 6, 49 days after sowing. 



On the other hand, the latest forms do not come into ear in less than 

 150 to 1 60 days, even when sown at the most propitious date. 



For each form of wheat there is a date before which ears are never 

 produced when grown in the open field no matter at what time the grain 

 is sown : it varies with the amount of light, mean temperature, and other 

 climatic conditions of the place of growth. 



At Reading the earliest date at which wheats can be made to come 

 into ear is about the middle of May, and this is the case only with very 

 early Chinese and Indian forms sown in autumn of the previous year. 



The latest period at which ears escape from the leaf-sheath at Reading 

 is some time during September or October, the exact date being subject 

 to much more fluctuation than the time of the earliest appearance of ears. 

 At such late season the " shooting " or expansion of the stems is very 

 irregular, and only a few ears of each plant are pushed out ; these die off 

 as the autumn advances and do not ripen grain. 



