Hyphalike haustoria of the haploid stage of Cronartium ribicola in Pinus monticola observed with the scanning electron microscope1

摘要

AbstractHaustoria of the haploid stage (n stage) ofCronartium ribicolain bark cells ofPinus monticolawere studied with the aid of the scanning electron microscope. The morphology of mature haustoria in all kinds of bark cells was consistently filamentous or elongate (hyphalike). Only immature haustoria are short and globose or reniform. Immature and mature haustoria are constricted at the point of passage through the host cell wall. N stage C.ribicolahyphae are characterized as having haustoria that are morphologically similar to intercellular hyphae.