64 Principles of Plant Culture. 



84. The Storage of Reserve Food. In healthy 

 plants, food is usually prepared faster than it is con- 

 sumed by growth. The surplus may be in the form of 

 starch, as in the potato (Fig. 16), wheat and sago; 

 sugar, as in the sugar cane, sugar maple and beet; or 

 oil, as in cotton seed, flax seed and rape. Aside from 

 the seeds, which are always stocked with reserve food, 

 certain plants living more than one year as the potato, 

 beet, onion, kohl-rabi, etc., have special accumulations 

 of food in certain parts, and the parts of plants that 

 contain such reserve food are most valuable as food for 

 man or animals. The proportion of starch stored in 

 potato tubers is not constant, hence the food value of 

 different samples of potatoes may vary greatly. In 

 woody plants, the surplus food is more evenly distrib- 

 uted through the different parts, though the older leaf- 

 bearing wood is usually best supplied. 



85. Plants Use their Reserve Food in the produc- 

 tion of flowers and seeds (134 A), and in repairing dam- 

 ages, as the healing of wounds (72), or the replacement 

 of leaves destroyed by insects or otherwise. Annual 

 plants (337) expend all their reserve food in flower 

 and seed production and then perish as soon as the seed 

 is ripe. Biennial plants devote the first season of their 

 life to storing an abundant food supply, which is ex- 

 pended in flower and seed production the second year. 

 Our seed crops, as oats, corn, peas and beans, are mostly 

 annuals; our vegetables other than seeds, as beets, cab- 

 bage, parsnips and celery, are mostly biennials. Peren- 

 nial plants, in normal condition, expend only a part of 

 their reserve food in any one season for the production 



