Morphological and anatomical changes associated with gall formation on the leaves of Cussonia spicata

The simple tubular galls which develop on the leaves of Cussonia spicata are apparently caused by a new species of psylla, of the genus Trioza. As a result of feeding by the insect, most of the leaf cells in the vicinity of the feeding sites resumed meristematic activity and divided. As a consequence, the normal leaf structure became disorganized and the very distinctive chlorotic galls developed. During gall development the chloroplasts decreased in number and size and the grana degenerated. Associated with this degeneration was the appearance of phytoferritin. These changes could be correlated with lower levels of endogenous cytokinins in the gall tissue.S. Atr. J. Bot. 1982, 1: 58- 6