GRAMINEjE (pOACEiE); GRASS FAMILY 75 



meters. Tillers are produced freely in moderately warm, 

 sandy soil. The number of tillers is also increased by 

 a large amount of reserve material in the seed, and by high 

 soil fertility, and by thin seeding. The effect of this last 

 factor is well shown in the following data taken from the 

 Nebraska Experiment Station Bulletin 127: 



Tillering of Oats 



Pecks of seed sown per o^. , ^ 



gjjg ^ I stems per loo plants 



4 466 



8 279 



16 140 



Total number of stems 

 per acre 



1,419,000 

 1,732,000 

 2,283,000 



The production of tillers in the small grains is altogether 

 desirable from the farmer's standpoint, as it is an important 

 factor determining yield. 



Bulbous Grasses. — In a few species such as timothy 

 (Phleum pratense) and tall oat grass (Arrhenatherutn elatius), 

 some of the lower, short internodes are enlarged into bulb- 

 like bodies containing a store of nourishment. 



Rhizome-bearing Grasses. — Perennial grasses usually 

 have rhizomes or rootstocks, horizontally elongated under- 

 ground stems, which give rise to erect annual stems that 

 bear foliage leaves and flowers. These underground stems 

 are very efl&cient as reproductive organs, for, as a result of 

 their elongation in the soil, the plant is able to invade areas 

 already occupied by other plants. Furthermore, each root- 

 stock is capable of budding a new plant at every node, and 

 should it be dragged from the ground by cultivating machin- 

 ery and broken into a number of separate pieces, each piece 

 will give rise, under favorable conditions, to a new plant. 

 Quack grass (Agropyron repens), and many other of our 



