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ARS Home » Pacific West Area » Logan, Utah » Poisonous Plant Research » Research » Publications at this Location » Publication #237208
Title: The Biogeographical Distribution of Duncecap Larkspur (Delphinium occidentale) Chemotypes and Their Potential Toxicity

Author
item Cook, Daniel
item Gardner, Dale
item Pfister, James
item Welch, Kevin
item Green, Benedict - Ben
item Lee, Stephen

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2009
Publication Date: 5/21/2009
Citation: Cook, D., Gardner, D.R., Pfister, J.A., Welch, K.D., Green, B.T., Lee, S.T. 2009. The Biogeographical Distribution of Duncecap Larkspur (Delphinium occidentale) Chemotypes and Their Potential Toxicity. Journal of Chemical Ecology 35:6443-652

Interpretive Summary: Larkspurs (Delphinium spp.) are poisonous plants found on rangelands in Western North America. Larkspur’s toxicity has been attributed to the norditerpenoid alkaloids which are divided into two main structural groups; the highly toxic MSAL-type and the less toxic MDL-type. Plants high in the MSAL-type alkaloids are thought to be the most toxic to cattle and the concentrations of these alkaloids have been used as a predictor of plant toxicity. Duncecap larkspur, Delphinium occidentale, occurs throughout much of the Intermountain West and Northwestern United States. Specimens from field collections and herbaria deposits were evaluated taxonomically and chemically. Two distinct alkaloid profiles were identified: one that contains the MSAL-type alkaloids and one that contains very little, if any, MSAL-type alkaloids. Thus, plants with these two alkaloid profiles should differ in their toxic potential. Each alkaloid profile was unique in its geographical distribution. These findings have important implications in grazing management decisions on D. occidentale-infested rangelands and they demonstrate that botanical classification alone is not a good indicator to determine the toxic risk of D. occidentale.

Technical Abstract: Larkspurs (Delphinium spp.) are poisonous plants found on rangelands in Western North America. Larkspur’s toxicity has been attributed to the norditerpenoid alkaloids which are divided into two main structural groups; the highly toxic (N-methylsuccinimido) anthranoyllycoctonine type (MSAL-type) and the less toxic 7,8-methylenedioxylycoctonine type (MDL-type). Plants high in the MSAL-type alkaloids are thought to be the most toxic to cattle and the concentrations of these alkaloids have been used as a predictor of plant toxicity. Duncecap larkspur, Delphinium occidentale, occurs throughout much of the Intermountain West and Northwestern United States. Specimens from field collections and herbaria deposits were evaluated taxonomically and chemically. Two distinct alkaloid profiles were identified: one that contains the MSAL-type alkaloids and one that contains very little, if any, MSAL-type alkaloids. Thus, plants with these two alkaloid profiles should differ in their toxic potential. Each alkaloid profile was unique in its geographical distribution. These findings have important implications in grazing management decisions on D. occidentale-infested rangelands and they demonstrate that botanical classification alone is not a good indicator to determine the toxic risk of D. occidentale.