XVI International Botanical Congess

Caltha leptosepala D.C. (Ranunculaceae) is a perennial herb of alpine wet meadows. At dispersal, seeds of this species contain a rudimentary embryo. We hypothesize that embryo development takes place within the dispersed seed beneath alpine snowbanks. Seeds were stratified at 2.5*C and collected at regular intervals for germination trials and histological analysis. Newly-dispersed seeds are not germinable. The embryo occupies approximately 12.5% the length of the seed and has poorly differentiated cotyledons. Embryos develop to critical germination size over a 7 month period. Germination of seeds increases with stratification time, and reaches 70% at 7 months. Rudimentary embryos in C. leptosepala appear to function as a dormancy mechanism which prevents seeds from being lost to fall germination mortality.