The way in which the branching of a tree depends on the buds is well shown in a lilac. The terminal bud does not usually develop, so that each of the two lateral buds just below grows out into a branch, producing the characteristic “forking.” In the lilac bud every gradation between scales and ordinary foliage leaves may be seen. Fig. 41.—Longitudinal section of twig of Sycamore. A, base of leaf; B, axillary bud; C, cork layer. (× 2.) (From a photograph by Mr. A. Flatters.) Fig. 42.—Cross section through leaf-bud of Beech. (× 6.) In the violet bud the two margins of the leaf are rolled inwards towards the midrib; while in the dock they are rolled backwards. Young fern leaves (Fig. 146) are not folded from side to side like the examples referred to above, but are rolled into a tight coil from apex to base. It is the upper surface of the leaf (frond) which is to the inside. As the leaf grows, the coil straightens out. EXERCISES ON CHAPTER IV. 1. Where and when are the buds of common English trees formed? (1901) 2. Show, by describing and drawing one example, that the branch of a tree may preserve a record of past seasons in the bark. (1901) 3. Draw an unopened bud of sycamore. Of what parts is it composed, and how are the parts arranged? (1901) 4. What can be seen inside a large bud of horse chestnut? On what part of the branch are the largest buds to be found? (1898) [Pg 66] 5. Upon what does the method of branching of a tree depend? Give examples. 6. Examine pollarded trees; what is the cause of their peculiarities? 7. Examine buds of various trees in spring, and try to discover in which cases the bud scales are (a) modifications of entire leaves, (b) modified leaf stalks, and (c) modified stipules. 8. Examine and describe the method of protection, during the summer, of the axillary buds of the plane. 9. Take a poplar shoot during late summer, and examine the corky separation-layer forming at the base of each leaf. Write an account of its use, and make drawings of its appearance. 10. The “heart” of a cabbage or lettuce is of lighter colour, sweeter taste, and more tender texture than the external leaves. How do you explain these differences? (King’s Schol., 1902) 11. Describe and explain the effect of clipping a privet hedge. 12. Give an account of the changes in appearance in any common leaf during the whole period of its growth. Explain briefly what part the leaf plays in the life of the plant. (Certificate, 1904) 13. Explain precisely how you would decide whether a given specimen consisted of (a) one compound leaf, or (b) a twig bearing several simple leaves. [Pg 67] CHAPTER V. HOW STEMS DO THEIR WORK 11. THE DUTIES OF STEMS.