Scapania mucronata Buch in Scotland

Abstract

Regeneration from detached leaves at 20°C in 12 h days was studied in six species. Of the four species of Polytrichum and two of Pogonatum studied, only Pogonatum aloides did 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. formosum and P. juniperinum developed long, muchbranched secondary protonemata which produced buds at intervals. Pogonatum urnigerum developed buds without an initial protonema, and Polytrichum piliferum short, 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. In Pogonatum urnigerum the amount of regeneration tended to decrease from apex to base of leaf, while in the Polytrichum species 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.