Submitted to: Journal of Chemical Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/17/2001
Publication Date: 4/4/2002
Citation: RALPHS, M.H., WELSH, S.L., GARDNER, D.R. DISTRIBUTION OF THE LOCOWEED TOXIN, SWAINSONINE, IN POPULATIONS OF OXYTROPIS LAMBERTII. JOURNAL OF CHEMICAL ECOLOGY. 2002. Interpretive Summary: Lambert's locoweed has been considered one of the major locoweeds, but recent studies failed to detect the toxic alkaloid swainsonine in some of its populations. A field survey was conducted of several populations of the three varieties (var. Lambertii, bigelovii, atriculata) throughout their geographical ranges to document the presence of swainsonine. Swainsonine was found in only 5 populations of variety bigelovii in the southwest portion of its distribution in southern Utah, Arizona and southwestern New Mexico. No swainsonine was found in the eastern portion of lambertii, nor of the other two varieties. It is suspected that a plant fungal endophyte may produce swainsonine within the plant and thus be responsible for the variability in the presence of swainsonine.
Technical Abstract: Oxytropis lambertii has been considered to be one of the major locoweeds responsible for livestock poisoning on rangelands, but there has been much confusion as to is taxonomic identity. The objective of this study was to conduct a field survey of several populations of each of the three varieties (var. Lambertii Pursh; var bigelovii A. Gray; var. articulata E. Greene Barneby) to document the presence or absence of the locoweed toxin, swainsonine. Swainsonine was found at detectable levels in only 5 populations of var. bigelovii in the southwest portion of its distribution in southern Utah, Arizona and southwestern New Mexico. No swainsonine was detected in populations in the northeast areas of its distribution (eastern Utah, Colorado, northeastern New Mexico). The other varieties, articulata and lambertii, also did not contain swainsonine. It is suspected that a plant fungal endophyte may be responsible for the high variability in swainsonine content in populations of O. lambertii.