Peculiar structures occurring in vessel walls of the susceptible carnation cultivar Early Sam infected with Fusarium oxysporum f.sp. dianthi

Ultrastructural and cytochemical studies of infection by Fusarium oxysporum f.sp. dianthi (Prillieux & Delacroix) Snyder & Hansen in susceptible carnation (Dianthus caryophyllus L.) plants have disclosed conspicuous amounts of an unusual dense material that extends long distances in vessel walls. This material, which at times was circumscribed by bands of material that labelled for chitin and was closely linked to large fungal or microhyphal cells, contained membranous and filamentous structures and opaque particles of uniform appearance. At times, the latter aggregated into crystalline bodies.