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MISCELLANEOUS. 



Lessons in Elementary Botany. II. 



By J. C. Willis. 

 THE SHOOT. 



This can usually be distinguished from the root in the sprouting seed, the 

 shoot going upwards, the root downwards. The shoot is usually made up of stem 

 and leaves, and the leaves are borne upon the stem at definite points called the 

 nodes. (PI. I., June T.A.) The stem usually branches in the axils (or armpits) of 

 the leaves, i.e., the angles between them and the stem ; and the branches repeat 

 the structure of the stem, themselves bearing leaves, and branching in their axils. 

 Of course there are also many stems, e.g., those of palms, which do not branch. 



The leaves want plenty of light and air, and the object of the stem is to 

 support and spread them out to get these, and to carry water to them from the 

 roots. The average stem grows straight upwards, this being directly towards the 

 brightest light. That light is the main factor in this direction of growth may be 

 seen by placing a plant with the light to one side of it, for instance by putting it in 

 a window, when it will be found that the stem will grow towards the side from 

 which the light comes. The leaves on the other hand tend to place themselves 

 at right angles to the light, as may also be illustrated by putting a plant for some 

 days in a window, when the younger leaves will all arrange themselves to suit the 

 new direction of light. 



It will be noticed in this experiment that the old parts of stem and older 

 leaves, which have quite finished growing will not move into new positions— only 

 the still growing portions are able to move. 



If a stem be examined it will be found that while on the old parts the 

 leaves are usually at about equal distances apart, as we approach the growing end 

 the leaves get closer and closer together, till at last they are all crowded up in a 

 budl(Ph I., June T.A.) at the tip. Every stem and branch ends in a bud, composed 

 of younger and younger leaves folded closely over one another, with shorter and 

 shorter gaps between them. 



The bud must obviously be tender, and requires some protection, otherwise 

 it will be damaged by heat causing excessive evaporation and shrivelling, or by 

 other causes. As a rule the outer sides of the outer leaves of the bud are covered 

 with hairs, or sometimes with wax, or the outer leaves, as in Rhododendron, are 

 mere scales for the sole purpose of protecting the young bud. Sometimes the bud is 

 protected by its position in the shelter of the mature leaves, or by lying close 

 between the stalk of the leaf in whose axil it arises and the main stem, or in other 

 ways. Examine a lot of buds, and see if you can find one which really has no 

 protection to the delicate young inner leaves. 



The stems of most plants elongate and must consequently grow in thickness 

 to carry more water that is now required by the increased number of leaves, and 

 to carry the extra weight involved. As it grows, the old green outer skin or bark 

 gets stretched, and presently begins to crack off, being replaced from below by a 

 brown bark, the bark to which the name is usually given. This bark in turn 

 stretches and cracks off, but is continually renewed from below like the skin of the 

 hand. This brown bark as a matter of fact consists of cork (the cork of commerce 

 is simply the bark of a Mediterranean species of oak), and as every one knows cork 

 is water-and air-proof. Now the stem, being alive, requires, like all other living 



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