Three proaporphine bases provisionally designated crotsparine (I), m.p. 193-194°, N-methyl-crotsparine (III), m.p. 223-225°, and N,O-dimethylcrotsparine (IV), m.p. 125-127°; two dihydroproaporphines, crotsparinine (II), m.p. 184-185°, and N-methylcrotsparinine (V), m.p. 160-161°, and the known aporphine alkaloid, sparsiflorine (X), m.p. 229-231°, have been isolated from Croton sparsiflorus Morong and their structures and stereochemistry assigned. N-Methylcrotsparine is of biological interest as a hypotensive agent. © 1970.