108 
SURVIVAL ON LAND AND SEA 
is about one foot in height and has blue flowers and inflated 
leaf stems. The young leaves, leafy stalks, and the flowering 
parts may be eaten in an emergency, either steamed or boiled. 
In the soft mud along the banks of streams, along the edges 
of ditches, and also in abandoned rice fields, is a plant called 
the arrowhead, which has an underground stem or tuber that 
is edible when cooked. Other water plants also grow in such 
places and all parts of them can be eaten when cooked as 
greens. Ferns growing in such places also may be used as 
food. The young shoots are better and may be eaten raw or 
when cooked as greens. (See fig. 32.) Of course, many of the 
trees and other forms of plants already described, bamboos, 
bananas, palms, etc. may be found along the streams as well as 
in the other locations mentioned. 
Rice sometimes escapes from cultivation and may be found 
growing wild along the banks of streams and ditches. 
Swamps 
Swamps often occur along rivers and smaller streams, as 
well as along the coasts, and some food plants are to be found 
there. Edible ferns occur in fresh water swamps. The wild 
form of the Chinese water chestnut (Fig. 33) is often found in 
the open fresh- water swamps of the Old World. Its nearly 
round, hard tubers are produced underground. They are ex- 
cellent when boiled or roasted. Another plant that grows in 
fresh-water swamps and swampy places more or less in the 
open has very large leaves and stalks more or less covered 
with short spines (Fig. 34). It has a large underground part 
that is rich in starch, but it should be eaten only after it is 
