Fig. 7

Sclerenchyma in the wall of mature galls induced by O. robiniae. a Control. Network of the vascular bundles in robinia leaf, outside the gall; part of the cleared leaf; view in Nomarski contrast. b Part of the cleared gall, stained with Trypane blue. The boundary between the normal leaf (upper part) and the gall (lower part) is visible. In the area of gall the vascular bundles are surrounded by sclereids (sc). c Cleared part of the mature gall; vascular bundles are surrounded by one layer of sclereids; view in Nomarski contrast. d Middle part of the mature gall wall; sclereids are present around all small vascular bundles; specimen stained with Trypane blue. e Magnified image of the vascular bundle enclosed immediately by sclereids. It is clear, that sclereids (brachysclereids) are lignified cells of parenchyma bundle sheath. Note in sclereids the thick call wall containing numerous simple pits; specimen stained with Trypane blue. f Specimen of the mature gall wall stained with phloroglucinol and HCl; lignin in sclereids and tracheary elements is stained red. Abbreviations: sc - sclereid, vb - vascular bundle. Bar = 20 μM