There is need for descriptive work on the succession of fungi on decaying plant remains above ground. The succession of fungi on stems of Dactylis glomerata during a 2-year period following flowering is described. Anatomical, physiological and physical variations within the grass tussock are discussed. The upper internodes frequently have a water content of less than 15% of the dry weight, which is probably a limiting level for fungal growth, while the lower internodes maintain a consistently higher water content. The capacity of the stems to hold water declines with age. Cocksfoot stems were removed at monthly intervals from 3 different localities and the distribution of fruit bodies of fungi on the various internodes recorded. Analysis of the distribution of the more common fungi shows a number of distinct patterns of distribution. Group I. Cladosporium herbarum, Epicoccum purpurascens, Alternaria tenuis, Leptosphaeria micro-scopica and Pleospora vagans are primary saprophytes which colonize tissues as they become moribund, and advance up the stem as new leaves unfold. These fungi persist on the upper internodes until the following year. The spores of these fungi germinate readily and germ tubes grow quickly. Group n. Acrothecium sp. is normally confined to the damper tussock base early in the succession. On fresh cut-down stems it may spread to the upper internodes. Spore germination occurs only at or near saturation and growth is slow. Group III. Mollisia palustris and Leptosphaeria nigrans fruit in the tussock base in the spring and summer following flowering and are apparently confined there by demands for high humidity. Fruiting is probably stimulated by increasing temperature. Group IV. Helminthosporium hyalospermum and Tetraploa aristata fruit in the tussock base in the summer following flowering and persist there and on old fallen stems during the second summer. Germination of spores and growth of germ tubes is less rapid than for fungi in group I. Group V. Selenophoma donacis and Mycosphaerella recucita fruit on the upper internodes in the late summer of the year following flowering.