THE WHEAT PLANT 



During the cold autumn months wheat makes comparatively little 

 growth, although the difference between plants of the same form sown in 

 September and those sown in November, in respect of the number of 

 shoots which they possess, is sometimes considerable. So far as the 

 " shooting " and " earing " processes are concerned, they are evidently in 

 much the same state of development, or very little in advance of each 

 other, for observations of the growth of many varieties over several seasons 

 show that rows of the same wheat sown during September, October, or 

 November come into ear within 3-5 days of each other in the following 

 June ; also, those sown in January and February usually send forth their 

 ears nearly together, although later than those sown in autumn. 



Sown in January or February they send forth their ears later, the 

 early sorts from 4 to 7 days, the later varieties as much as 10 to 20 days later 

 than the same kinds sown in autumn up to November in the previous 

 autumn. 



ANATOMY OF THE CULM AND RHIZOME 



A culm or straw is composed of the following tissues : 

 (i) The epidermis ; (2) the hypoderm or zone of mechanical tissue 

 beneath the epidermis ; (3) green assimilating parenchyma ; (4) colourless 



ground parenchyma ; and 

 (5) the vascular bundles. 



In transverse section the 

 straw is almost circular in 

 most Bread wheats (T. vul- 

 gar e), but in other races, 

 especially T. dicoccoides, T. 

 turgidum, and T. polonicum, 

 the outline is wavy, the sur- 

 face of the culm in these 

 being more or less deeply 

 furrowed . 



(i) The epidermis, which 

 is about 25-30 /x thick, is 

 formed of narrow elongated 

 cells 150-250 fj, long, with 

 short square cells 9-13 [J> 



rl 



FIG. 70. Lines of stomata 

 of the culm ( x 50). 



FIG. 71. Epidermis 

 of the culm ( x 210). 



across intercalated among 

 them at intervals . In wheats 

 with the furrowed straws, short papillae or scabrid hairs are often 

 present, particularly in the furrows. Single or double lines of stomata 

 similar to those found on the leaf-blade and sheath are present (Fig. 70), the 

 stomata being 200-250 /z apart in the row. The cells over the hypoderm 



