The title alkaloids were isolated from Spiraea japonica, and their absolute stereostructures were elucidated by chemical, spectral, and x-ray crystallographic methods as 1 and 2. Although both 1 and 2 exist as a single epimer with the 19(S) configuration in the solid state, fast equilibration occurs in solution to form a pair of C19 epimers in an approximate ratio of 1:1. © 1986.