CHAPTER V. 

 The Mode of Growth and the Classification of Galls. 



The remarkable diversity in the shapes and sizes of galls is 

 surpassed by the many and various manners in which they 

 grow, and the positions which they occupy on the plants 

 and trees. 



The mode of growth is very interesting, and should be 

 carefully observed and thoroughly noted by the student and 

 collector. 



Galls may be found on every part of plants and trees, from 

 the roots to the flowers and seeds. When upon the roots, 

 trunk, branches, twigs, stems, stalks, or leaves, their growth 

 does not interfere with the fructification of the plant, nor, as 

 a rule, with its general development ; but when the petals, 

 seed-vessels, or other reproductive functions are involved, 

 injury of a more or less derogatory character is the result. 

 The following are the predominant modes of growth with 

 typical examples of each, which galls assume. The charac- 

 teristic features give to each growth an individuality which 

 is valuable in one method of classification. 



I. Axillary = Eriophyes axillaris. IX. Hirsute = Rhodites roses. 



II. Coalescent = Hormomjia cap- X. Imbricated = Adelges abietis. 



rem. XI. Pedunculated = Teiraneura 



III. Conglomerated = Diastrophus iilmi. 



rubi. XII. Pilose = Aulax glechoma;. 



IV. Cymbiform = Monochetus sul- XIII. Pubescent = Hormomyia pili- 



catus. gera. 



V. Elongated = Diplosis botularia. XIV. Pustulate = Eriophyes pustu- 



VI. Glabrous = Diplosis tremula:. latum. 



VII. G\ossy = Urophora cardici. XV. VMgost = Aulax hypocharidis. 



VIII. Gregarious = Phyllocoptes ace- XVI. Rosaceous = Cecidomyia ro- 



ricola. saria. 



