. Elementary principles of agriculture : a text book for the common schools . 10 Elementary Principles of Agriculture 15a. Have the pupils make a list of all the common plants with which they are familiar that are started from seeds; also, those that are started from bulbs, roots, and cuttings. 16. Structure of Seeds. When we look at a bean, we see it is covered with a thin skin, or "seed-coat," which is quite smooth except at the edge where it was attached to the bean pod. Now, if we remove this coat from a seed (using one that has been soaked in water over-night), two large, thick
. Elementary principles of agriculture : a text book for the common schools . 10 Elementary Principles of Agriculture 15a. Have the pupils make a list of all the common plants with which they are familiar that are started from seeds; also, those that are started from bulbs, roots, and cuttings. 16. Structure of Seeds. When we look at a bean, we see it is covered with a thin skin, or "seed-coat," which is quite smooth except at the edge where it was attached to the bean pod. Now, if we remove this coat from a seed (using one that has been soaked in water over-night), two large, thick " seed leaves," or cotyledons (cot-y-le-dons), joined to a minute stem, may be seen. (Fig. 8.) One end of the stem is round and plump, while the other bears two tiny leaves. The latter Fig. 8. Bean seed split open is the stem end, and bears the to show parts of plantlet. ^^^^^ ^^^_ ^j^^ ^,^^^ ^^^^^^ ^^^^ the other end. Thus we see that the bean has all the parts of a plant, but a very small or embryo plant. 17. Stored-up Food in Seeds. Plants need food to build up their bodies and provide energy, just as animals do. The cotyledons do not look like ordinary leaves, because they are filled with much starch and other substances, to nourish the plantlet when it begins to grow. Substances stored up in seeds like this are called *' reserve ; The reserve food in the case of the bean is largely starch. In some plants it is largely oil, as in cotton seed, sunflower, pecan, flax, etc. Besides starch and oils, another class of substances is present as a reserve food of all kinds of seeds, called pro- teids. Proteids from animal bodies are familiar, as the whites and yolks of eggs, clabber of milk, clot of blood, etc. (See Appendix C.)
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