The major cyanogenic glycoside of Guazuma ulmifolia (Sterculiaceae) is (2R)-taxiphyllin (>90%), which co-occurs with (2S)-dhur-rin. Few individuals of this species, but occasional other members of the family, have been reported to be cyanogenic. To date, cya-nogenic compounds have not been characterized from the Sterculiaceae. The cyanogenic glycosides of Ostrya virginiana (Betulaceae) are (2S)-dhurrin and (2R)-taxiphyllin in an approximate 2:1 ratio. This marks the first report of the identification of cyanogenic compounds from the Betulaceae. Based on NMR spectroscopic and TLC data, the major cyanogenic glucoside of Tiquilia plicata is dhurrin, whereas the major cyanide-releasing compound of Tiquilia canescens is the nitrile glucoside, menisdaurin. NMR and TLC data indicate that both compounds are present in each of these species. The spectrum was examined by CI-MS, 1 H and 13 C NMR, COSY, 1D selective TOCSY, NOESY, and 1 J/ 2,3 J HETCOR experiments; all carbons and protons are assigned. The probable abso-lute configuration of (2R)-dhurrin is established by an X-ray crystal structure. The 1 H NMR spectrum of menisdaurin is more com-plex than might be anticipated, containing a planar conjugated system in which most elements are coupled to several other atoms in the molecule. The coupling of one vinyl proton to the protons on the opposite side of the ring involves a 6 J-and a 5/7 J-coupling pathway. A biogenetic pathway for the origin of nitrile glucosides is proposed.