66 SEEDS AND FRUITS 
flour depends much upon the amount and quality of protein 
(gluten) which the endosperm contains. When there is a good 
quality of gluten present, the flour is characterized as being strong 
and is the kind which bakers prefer. Graham flour is the entire 
grain finely ground. In making entire wheat flour, after the 
grain is finely ground, some of the bran is removed. The em- 
bryo, which constitutes about eight per cent of the grain, contains 
much fat and oil, and, if the embryo is ground up with the flour, 
the oil is apt to become rancid and impair the flavor of the flour. 
For this reason, the embryo is removed in making high grade 
flour and sold with the middlings 
or used in making breakfast foods. 
(Fig. 70.) 
Oat Kernel. — In general form 
and structure the Oat kernel is 
similar to the grain of Wheat, ex- 
eepting that it is more elongated 
and the ovary wall is hairy. 
The kernel usually remains en- 
closed in the lemma and palea, 
and the quality of Oats depends 
upon the proportion of hull to 
kernel. The endosperm contains 
Fic. 70.—Section through the 
outer portion of a Wheat grain. w, 
ovary wall, often called pericarp; J, 
testa or secd coat; u, alcuron layer 
with cells filled with grains of protein; 
g, starchy endosperm with cells large 
and filled mainly with starch grains. 
protein, starch, and fat and is a 
valuable food for both man and 
live stock. 
Comparison of Seed Types. — 
The three types of seeds differ 
fundamentally in the number of 
cotyledons and in the location 
of the stored food. The difference in the number of cotyledons 
is probably the more important one because all Flowering Plants 
have been divided into two classes on the basis of whether or not 
one or two cotyledons are present. Plants with seeds having 
but one cotyledon are called Monocotyledons (one cotyledon). 
Not only the grains and all other Grasses, but also Palms, Lilies, 
Asparagus, Onions, and many other plants are Monocotyledons. 
Plants with seeds having two cotyledons, as in case of the Bean, 
and Buckwheat type, are called Dicotyledons (two cotyledons). 
Besides Beans and Buckwheat, many other common plants, 
Some protein grains are present in the 
starch cells. m, nucleus. 
