Translations:Benutzer:Arian/Klett-Mini-Test/1450/en

its hormonal action causes the two-dimensionality of the oak leaf to grow outward from the point of egg-laying into a pith gall — that is, into three-dimensionality. Within the gall that houses the larva, the leaf forms itself into a kind of spherical skin organ, a nourishment-tissue-rich interior that closes itself off against an exterior. Gall formations occur on other woody plants as well. The oak, however, is capable as a single host plant of producing over 100 different kinds of gall. Noteworthy is the high content of tannins and colorants in the galls, which again points to a premature sulphurization in the leaf zone, similar to what occurs in the bark and outer bark.