312 INTRODUCTION TO BOTANY 
About one third of the world’s supply of sugar comes from 
the sugar cane (Saccharum officinarum), which has at least a 
dozen varieties that thrive in tropical and sub-tropical coun- 
tries (fig. 234). This plant has a very heavy root system, 
from which several stalks grow. Its leaves are large and 
numerous, so that much chlorophyll work is possible; hence 
much sugar may be made by the plant. The stalks when full- 
grown are so well filled with sugar-laden sap that natives 
often use them directly as food. ‘The sap from good cane may 
contain from 17 to 18 per cent of sugar. After the leaves are 
stripped off, the stalks are cut and the sap is pressed from 
them by means of machinery specially designed for that pur- 
pose; after this the water is removed from the sugar by 
evaporation. Some sugar cane is grown in this country, but 
sorghum is more widely distributed and produces a sirup that 
is extensively used.1 
Sugar beets (Beta vulgaris) have been grown in Europe for 
many generations, but it is only in recent years that they have 
been widely grown in the United States. They have already 
become a prominent factor in the sugar industry. Sugar beets 
thrive in temperate climates, mature in a relatively short sea- 
son, and grow well in a wide range of soil conditions. Besides 
these advantages, they are very productive. The sugar pro- 
duced from beets is rapidly coming into general favor.? 
295. Fiber plants. Primitive people learned to use the 
strong-fibered grasses and the tough bark of some trees in mak- 
ing bands and cords for tying various articles. Leatherwood, 
or moosewood (Direa palustris), and Indian hemp (Apoeynum 
cannabinum), often so used by the early settlers in this country, 
have fibers of very great strength, which, when dry, are almost 
as strong as leather thongs. The making of cordage from plant 
fibers has become an important industry. Many grasses, palms, 
hemps, etc. have extremely long, strong fibrovascular bundles, 
which, when removed and twisted together, make twines of 
1" Sugar Cane in Porto Rico,”’ Bulletin 9, Porto Rico Agr. Exp. Sta., 1910. 
2 The Sugar Beet,” Farmers’ Bulletin 52, U.S. Dept. Agr., 1910. 
