GRAMINE^. CEREALS 48; 



surface of the soil is termed ' tillering,^ and is a common mode of 

 branching met with in all the cereals, and in grasses generally. 



No matter at what depth the seed is placed branching only 

 takes place at the nodes near the surface of the ground. If 

 placed deeply the first internode or two (d, C, Fig. 152, and a, 

 Fig. 154) elongate considerably, and are noticed as a tough, 

 wiry piece of stem when the plants are pulled up ; in shallow 

 sowing the internodes are short and scarcely visible. 



The number of ear-bearing shoots produced from a single 

 grain may, under some circumstances, be 100 or more; usually 

 it is not more than five or six. Varieties of cereals grown largely 

 for straw should tiller considerably ; for production of grain of 

 good quality two or three stems from each is sufficient. The 

 ears of much-tillered plants ripen unevenly as the stems are neces- 

 sarily not all of the same age, and those produced last are 

 smaller and weaker than the primary stem and its first two or 

 three branches. 



The amount of ' tillering ' depends upon both internal and ex- 

 ternal causes. Some species of grass 'tiller' more than others — 

 wheat and barley, for example, more than oats ; varieties of the 

 same cereal also differ considerably in this respect. 



Plants exposed to plenty of light ' tiller ' more extensively than . 

 those grown in shade. Thin-sowing promotes it by allowing 

 more light to reach each plant. Moreover, in thin-sown crops 

 more food-constituents are at disposal in the ground for each 

 plant than when crowded together, and the plants 'tiller' more 

 in consequence. 



On poor soils fewer stems arise from a single plant than on 

 good soils, and early sowing gives more time for the formation 

 and development of shoots, winter-sown wheat ' tillering ' more 

 than that drilled in spring. 



'Shooting' of the Corn. — The branches for some time after 

 they are produced in the 'tillering' process remain with unde- 

 veloped internodes ; and it is only the blades of the leaves upon 



