A hitherto unnoted species of Physoderma on the basal leaves of Juncus pelocarpus Mey. is described. The fungus produces light brown irregularly-placed spots on the outermost leaves. The endobiotic system is composed in addition to rhizoids of non-septate or 1-2 septate turbinate cells, resting spores and ovate haustorial-bearing cells. Resting spores germinate by dehiscence of a lid and protrusion of a finger-like zoosporangium. No epibiotic stage has as yet been seen. The host range of the fungus has not as yet been studied. This is the first account of a Physoderma on a member of the Juncaceae.