66 



SEED8 AND FRUITS 



flour depends much upon the amount and quaht}^ 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 embrj^o 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- 

 cepting 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 

 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, 



Fig. 70. — Section through 

 outer portion of a Wheat gram, w, 

 ovary wall, often called pericarp; t, 

 testa or seed coat; a, aleuron layer 

 with cells filled with grains of protein; 

 g, starchy endosperm with cells large 

 and filled mainly with starch grains. 

 Some protein grains are present in the 

 starch cells, n, nucleus. 



