64 Principles of Plant Culture. 



as oats, corn, peas and beans, are mostly annuals; our 

 vegetables other than seeds, as beets, cabbage, parsnips 

 and celery, are mostly biennials. Perennial plants, in 

 normal condition, expend only a part of their reserve 

 food in any one season for the production of flowers and 

 seeds, withholding the remainder for nourishment 

 through the winter and to develop leaves the following 

 spring. The reserve food in dormant cuttings (358) en- 

 ables them to form roots and expand their buds. 



Section VI. The Eoot and the Soil 



With the out- door cultivator, the part of the plant 

 environment that lies beneath the soil suiface is more 

 under control than the part that lies above it. He can 

 do little to change tlie composition or temperature of the 

 air or the amount of sunlight; lie may do much to influ- 

 ence tlie fertility, the texture, the di'alnage and the aera- 

 tion of the soil. A knowledge of tlie roots of plants and 

 of the soil in which they grow and feed, is tlierefore, of 

 the utmost practical importance. 



87. The Office of the Root. The roots of land plants 

 serve (a) to anchor the plant in the soil, enabling the 

 stem or stems of erect species to grow upright, and (b) 

 to supply the plant with water with its dissolved food 

 materials (63). 



88. The Root Originates in the Stem. As we have seen 

 the primary root develops from the lower or ''root-end" 

 of the hypocotyl (45). But lateral roots may develojj 

 freely from other parts of the stem. If -we examine the 

 base of the stem of a plant of Indian corn a few weeks 



