SECT. I. ORGANOGRAPHY AND GLOSSOLOGY. 



of the stem. In the annexed diagram (fig. 45.), a re- 

 presents a bud, developed on 

 a branch which is one year 

 old ; and this branch is seated 

 on another which is two years 

 old, and which originated 

 from a bud of the same age 

 as 6, which has not yet been 

 developed. 



(6l.) Direction of branches. 

 The general contour given 



to the whole foliage of trees, which bears the name 

 of " cyma," depends upon the angle which the branches 

 make with the stem at their point of union, combined 

 with the degree of rigidity which they possess. When 

 they stand out at various angles, more or less approach- 

 ing to a right angle, they are termed " divergent ; " 

 and, when such branches are rigid, a rounded form is 

 given to the cyma, as in the oak and elm. When the 

 angle is more obtuse, they are said to be " patent," or 

 " spreading." If they rise at a very acute angle, and 

 are packed close together into the pyramidal forms 

 assumed by the cypress and Lombardy poplar, they are 

 called " appressed." When they are very long, and so 

 flexible as to bend by their own weight, they are 

 " pendant," as in the weeping willow. But in that 

 variety of the common ash, which is also called " weep- 

 ing," the branches are rigid, and possess a natural 

 tendency downwards, from their very origin, and are in 

 this case termed " depressed." 



(62.) Modifications of Branches. 



Thorns. When a bud is imperfectly developed, 



it sometimes becomes a short branch, very hard and 



sharp at the extremity, and is then called a " thorn." 



We must not, however, confound the " prickle" 



with the thorn. The former of these is a mere 



prolongation of cellular tissue, from the bark, and 



may be considered as a compound kind of pubescence 



(art. 3L); whilst the thorn, containing both wood and 



B 3 



