6o 



Elementary Botany 



If they grow from any other part of the plant they are said 

 to be adventitious. 



At first the bud consists entirely of parenchymatous tissue 

 connected with the parenchyma of the stem. There is a central 

 conical mass around which, after a while, vessels and wood 

 cells are developed; outside these, parenchymatous tissue which 

 forms bark, and which is covered with little scales of paren- 

 chyma variously overlapping one another, forming the rudi- 

 mentary leaves. 



The portions of the young stem to which these leaves are 

 attached are known as nodes, whilst the stem between the 

 nodes forms the internodes. 



Fig. 90. — Branch spines of the Sloe 

 {PrJtmts spinosa). 



Fig. 91. — Prickles of the Rose. 



In cold and temperate climates, where the buds remain 

 dormant during the winter, unfolding during the following 

 spring, the outer surface is protected by modified scales, which 

 sometimes, as in the Horsechestnut and Poplar, possess resinous 

 secretions, and at other times, as in Willows, are covered with 

 hairs. These scales protect the young bud from the cold and 

 frosts of the winter, and fall off when it begins to develop in 

 the following spring. 



The commencement of the development of the bud is by the 

 growth of the internodes, by which the young leaves become 

 gradually separated from one another and the branch is formed. 



