PATHOLOGIC PLANT ANATOMY 



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grandifiora. They are formed on the side of the branches exposed to 

 the sun and the bark cells are elongated in a radial direction, finally 

 breaking through the epidermis as spongy masses of cells. Leaves 

 also produce intumescences. Originating in the mesophyll cells, they 



JC 



Fig. 144. — Cross-section of ^ part of a strongly hypertrophied bark of Ribes 

 aureum. K, Cork; P, periderm; H, abnormally elongated bark cells. {Kuster, 

 Pathologische Pflanzenanatomie, 1903 : 80.) 



appear as greenish or whitish pustules of varying size and beneath the 

 cells lose their chlorophyll content. Cataplastic hypertrophy explains 

 the origin of some intumescences. For example, the lower cells of the 

 several-layered epidermis of Ficus elastica are pressed together by the 



