AbstractDetached leaves ofPleurochaete squarrosain culture give rise to filaments and buds. In a nutrient-free medium and in the wild these filaments have features comparable to the rhizoids, while in the presence of nutrients they resemble chloronemata and caulonemata. The protonemal apparatus inPleurochaete squarrosaoriginates exclusively from the cells between the lamina and the midrib, while the buds grow both directly from these cells or from the protonemata. The formation of filaments and buds from leaves still attached to the stem is slower and less frequent, probably as a consequence of morphogenetic control by the apex. Asexual propagation inPleurochaete squarrosais discussed in relation to the experimental data and field observations. Regeneration from detached leaves is the major form of regeneration in this moss.