Abnormal Growth 



279 



Organoid Galls. Under this term Kiister (1910) included many cases of 

 abnormal development or distribution of organs which are clearly the 

 result of parasitism, nutritional disturbances, or other known causes and 

 which often show little constancy of form or structure. Such galls may 

 appear at some distance from the site of the stimulating agent. With these 

 are usually included similar types of abnormalities even if their causal 

 factors are unknown. 



In some of these galls it is chiefly the form that is abnormal. In the 

 leaves of various species of Juncus parasitized by Livia juncorum, for 

 example, the sheath reaches extraordinary size while the lamina remains 

 small or atrophied. In Populus tremula small stipules turn into large, leaf- 

 like structures. Eriophyces also produces floral abnormalities in which 



Fig. 11-3. Abnormal flower of 

 gloxinia, with extra petal-like 

 structures on the outer surface 

 of the corolla and an increase 

 over the normal number of 

 corolla lobes. ( From Worsdell. ) 



stamens or carpels become petal-like. Flower buds that have been 

 grafted in a place where leaf buds would normally be sometimes produce 

 unusually large and abnormal flowers, evidently because of nutritional 

 changes. 



Some of these changes are comparable to those occurring in regenera- 

 tion. Thus in vigorously regenerating shoots of Symphoricarpos simple 

 leaves become pinnately cut, and in regenerating stalks of Sambucus, 

 stipules may be converted into leaves. The removal of the main shoot 

 in the seedling of Vicia faba results in the formation of primary leaves 

 or transitional ones instead of those of mature type. It is well known 

 that decapitation, defoliation, and similar injuries lead to various 

 changes. Goebel (1882) thus obtained leaves instead of bud scales in 

 Prunus padus, and Blaringhem (1908) reported many morphological ab- 

 normalities due to wounding. The formation of cups or aecidia on 



