The Water of Plants and Its Movements. 61 
(73), or the replacement of leaves destroyed by insects or 
otherwise. Perennial plants depend upon their reserve 
food to nourish their protoplasm during the dormant period, 
when their leaves are wanting or inactive, and to supply 
themselves with new foliage and root-hairs in early spring. 
The reserve food in dormant cuttings (358) enables them to 
form roots and expand their buds. 
The surplus food of plants may be in the form of starch, 
as in the potato (Fig.’11), 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. In woody plants, the surplus 
food is more evenly distributed through the different parts, 
though the older leaf-bearing wood is usually best supplied. 
S6. How Plants Use their Reserve Food. Annual 
plants (337) expend all their reserve food in the production 
of very numerous flowers and seeds 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 
expended 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, 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. 
