AbstractRegeneration from detached leaves at 20°C in 12 h days was studied in six species. Of the four species ofPolytrichumand two ofPogonatumstudied, onlyPogonatum aloidesdid not regenerate from leaves. This result could be related to the fact that in nature only this species possesses persistent primary protonemata.Polytrichum commune, P. formosumandP. juniperinumdeveloped long, muchbranched secondary protonemata which produced buds at intervals.Pogonatum urnigerumdeveloped buds without an initial protonema, andPolytrichum piliferumshort, unbranched protonemal threads, each bearing a single terminal bud. In all cases regenerants arose from either the large cells at the bases of lamellae, or less often, basal cells of the lamellae themselves. InPogonatum urnigerumthe amount of regeneration tended to decrease from apex to base of leaf, while in thePolytrichumspecies the reverse occurred. No definite conclusions could be drawn with regard to the effect, if any, of leaf age on regeneration. Possibly the temperature experienced beforehand or some other seasonal factor, affects regeneration, but the question needs further investigation.