STUDIES OF SEED-PLANTS 165 



Note that the bud-scales are arranged in pairs, and that they be- 

 come softer and more leaf -like as you approach the center. When 

 all the scales have been removed, there remains a soft woolly object, 

 the young stem and leaves. Suggest a use for the hairy substance. 

 Sometimes the terminal bud is a flower-bud. Compare what you 

 have found in a closed bud with what you find in an opening bud 

 on a twig which has been standing in water in a warm room. Ob- 

 serve that such a bud has swelled, some of the outer scales have fallen 

 off, leaving a fresh ring of scars on the stem, the inner scales have 

 become larger and more leaf -like, the shoot has elongated, the leaflets 

 are separating and unfolding. 



Compare buds from various trees and shrubs. 



Leaves are formed folded in buds. This is necessary for 

 two reasons: (1) leaves in a bud must take up as little 

 space as possible; (2) young tender leaves must have as 

 little exposed surface as possible to the dry and cold air of 

 winter. The folding of the leaves in the bud is known in 

 botany as vernation. 



Examine buds of various trees and shrubs such as lilac, tulip-tree, 

 hickory, beech, currant, etc., for types of vernation. Also examine 

 naked buds. 



Bud-like Structures. The cabbage head and the onion 

 bulb both illustrate the structure of a bud; but it should 

 be noted that they are not true buds, for they represent 

 fully developed shoots with very short stems. Examine 

 both of them in longitudinal sections obtained by cutting 

 through the centers. 



158. Position of Buds and Branches. In the study of 

 the horse-chestnut twig, attention was called to the fact 

 that buds appear in the axils of leaves and are either terminal 

 or lateral. But buds often occur on other parts of plants, 

 for instance, on the root or along the trunks of trees and even 

 on the notches along the margin of leaves (e.g., in Bryophyl- 

 lum). Such buds are abnormal in position and are known 

 as adventitious. They develop on some trees when large 

 branches have been cut off, and advantage is taken of this 



