GRASS TYPE OF SEEDS 61 
the seeds themselves are valuable on account of the oil, protein, 
starch, or alkaloid-like substances which they contain. From the 
endosperm and embryo of the Flax seed, linseed oil, the chief sol- 
vent for paints, is obtained. After the oil is pressed out of the 
flax seed, there remains the cake, which has considerable value as 
a feed for stock. The Castor Bean yields castor-oil which is 
much used as a medicine and sometimes as a lubricant and illu- 
minant. Buckwheat, which contains much starch and some fat 
and protein, is much used for food when ground into flour. Often, 
as in case of the Tomato, Potato, Beet, and Tobacco, the value 
of the plants depends upon the fruit, tubers, roots, or leaves, and 
not upon the seed, which in these cases has no value except for 
growing new plants. Of the weed seeds of this type, some com- 
monly occur as impurities among the seeds of Clover, Alfalfa, 
Flax, and the small grains and, when present in considerable quan- 
tities, they either lower the price or prevent the sale of these agri- 
cultural seeds, thus bringing loss to the farmer. In case of Cow 
Cockle and Corn Cockle, the seeds, which are frequently found 
among the small grains, are poisonous and when ground with 
Wheat make the flour unwholesome and when fed with grain to 
stock often cause injury. Other weed seeds of this type, as those 
of Dodder, Morning Glories, Black Bindweed, Sheep Sorrel, and 
others are objectionable because the plants themselves hinder 
the cultivation and growth of useful plants. Sometimes, as in 
case of the Black Nightshade and Jimson Weed, the plants are 
polsonous. 
Grass Type of Seeds. — As the name suggests, these are the 
seeds of the Grass family, the family to which Corn, Wheat, Oats, 
Rye, Barley, and Rice belong and hence the family most depended 
upon for food. Many of the Grass seeds, as in case of Timothy, 
Red Top, Blue Grass, etc., though not used for food, are valuable 
because the plants themselves are useful for pasture and hay. 
Some of the Grasses, however, are regarded as weeds and their 
seeds are often troublesome impurities among agricultural seeds. 
As previously noted, in structure the seeds of the Grass type 
are not true seeds. Besides a seed, they contain the ovary wall, 
called the pericarp, which remains about the seed as a closely 
fitting jacket. They are one-seeded ovaries and hence struc- 
turally they are fruits rather than seeds. Although popularly 
known as a seed, this fruit-like structure of the Grasses is scien- 
