The diterpene alkaloid content was used to assess the chemical taxonomic diversity in three larkspur species. Samples (n=163) were collected from 18 different locations in five western states, extracted and analyzed for diterpene alkaloids using electrospray mass spectrometry. The data were statistically analyzed using canonical discriminant analysis and analysis of variance. Delphinium glaucum samples were easily grouped and were significantly different from all other groups (P<0.005) for two compounds. Delphinium barbeyi and Delphinium occidentals were found to be distinct groups, but more closely related. Samples representing a putative hybrid between D. barbeyi and D. occidentale were found to be closely related to D. occidentals, but were significantly different from all other groups. These data support the classification of D. glaucum, D. barbeyi, and D. occidentals as distinct species and suggest that a possible hybrid is more similar to D. occidentale than D. barbeyi. (C) 2002 Elsevier Science Ltd. All rights reserved.