Published online by Cambridge University Press: 01 January 1997
The haustorial morphology of 21 Ravenelia species, two Kernkampella species, and four leguminicolous Uredo and Uraecium species which are probably related to Ravenelia, was investigated by light microscopy. Three different kinds of interaction could be found: (1) species with haustorial complexes comprising dikaryotic haustoria and intracellular hyphae. These species showed strictly intracellular growth of the parasitic mycelium. (2) Species with only dikaryotic haustoria, and (3) species with only intracellular hyphae or monokaryotic haustoria. Complexes of dikaryotic haustoria and intracellular hyphae were found in 17 of the investigated Ravenelia species and three Uredo species. Three Ravenelia species revealed dikaryotic haustoria, and Ravenelia lonchocarpicola had only intracellular hyphae. Complexes of dikaryotic haustoria and intracellular hyphae are probably the prevalent type of parasitic interaction in Ravenelia. The investigated Kernkampella species revealed dikaryotic haustoria.