{Stem. {Shoot····{ Plant body····{ {Leaf. {Root. KINDS OF SHOOTS. =691.= Since it is desirable to consider the shoot in its relation to environment, for convenience in discussion we may group shoots into four prominent kinds: (1) _Foliage shoots_; (2) _Shoots without foliage leaves_; (3) _Floral shoots_; (4) _Winter conditions of shoots and buds._ Topic (4) will be treated in Chapter XXXIX, section IV. [Illustration: Fig. 413. Lupinus perennis. Foliage shoot and floral shoot.] =692. (1st) Foliage shoots.=—Foliage shoots are either aerial, when their relation is to both light and air; or they are aquatic, when their relation is to both light and water. They bear green leaves, and whether in the air or water we see that light is one of the necessary relations for all. Naturally there are several ways in which a shoot may display its leaves to the light and air or water. Because of the great variety of conditions on the face of the earth and the multitudinous kinds of plants, there is the greatest diversity presented in the method of meeting these conditions. There is to be considered the problem of support to the shoot in the air, or in the water. The methods for solving this problem are fundamentally different in each case, because of the difference in the density of air and water, the latter being able to buoy up the plant to a great degree, particularly when the shoot is provided with air in its intercellular spaces or air cavities. In the solution of the problem in the relation of the shoot to aerial environment, stem and leaf have in most cases coöperated;[38] but in view of the great variety of stems and their modifications, as well as of leaves, it will be convenient to discuss them in separate chapters. [Illustration: Fig. 413_a_. Burrowing type, the mandrake, a “rhizome.”]