LEAVES, BUDS AND FLOWERS 79 



stem in which the leaves and internodes are in the embryo 

 stage. 



In most perennial plants, the rudimentary leaves that 

 form near the latter end of the growing season are changed 

 into bud-scales, which serve to protect their growing 

 points from excessive transpiration (74). Axillary buds 

 which have not yet expanded are clothed with similar 

 scales. Buds inclosed with scales are often called winter 

 buds. To shut out water more effec- 

 tually, the scales are coated with a waxy 

 or resinous layer in some plants, as the 

 horse-chestnut and balm of Gilead, 

 and to protect them further, especially 

 against excessive transpiration and 

 light when they first open, they are 

 lined in other plants, as the apple, 

 with a delicate cottony down. A 

 vertical section of the onion bulb may 

 be used as a magnified illustration of 

 a bud as it appears in winter, and that 

 of a head of cabbage of a bud unfolding Fig- 37.— Buds. L, 



lateral buds. 



in spring. 



128. Lateral buds. — Nature provides very early for 

 the next year's growth in perennial plants. With the 

 expansion of each leaf, a bud begins to form at its axil, 

 destined if need be to become a branch at a later time. 

 Sometimes, however, especially in very vigorous shoots, 

 the embryo buds at the axils of the earliest formed leaves 

 remain undeveloped. 



129. Branches develop from lateral leaf -buds (131). 

 In trees and shrubs (woody perennials), the lateral buds 

 do not usually push into growth until the spring after 

 their formation, unless the terminal bud is injured. In- 



