Alkaloid levels in Duncecap (Delphinium occidentale) and Tall larkspur (D. barbeyi) grown in reciprocal gardens: separating genetic from environmental influences.

The objective of this study was to determine whether differences in toxicity between Tall larkspur (Delphinium barbeyi) and Duncecap larkspur (D. occidentale) were genetically inherent within the species, or due to environmental influences unique to the different regions where they grow. There was no difference in the concentration of the toxic alkaloids between the two species when grown in common gardens. However, both species had higher concentration of toxic alkaloids when grown in the southern Rocky Mountain region which is characterized by summer monsoonal thunderstorms, compared to summer drought in the north. In a unique occurrence where Duncecap larkspur grew beside Tall larkspur, toxic alkaloids were very low in Duncecap larkspur, but total alkaloid concentration was often higher than in Tall larkspur.