From the aerial parts of Colletia spinosissima Gmel. (Rhamnaceae), two quaternary benzyltetrahydroisoquinoline alkaloids have been isolated. One, was identified as d-(-)-magnocurarine (I), and the structure of the other, which was named colletine, established as d-(-)-1-(4-methoxybenzyl)-2,2-dimethyl-6-methoxy-7-hydroxy-1,2,3,4-tetrahydroisoquinoline (II). © 1967.