Five Poisonous Range Weeds—When and Why They Are Dangerous

Abstract

Three larkspurs, halogeton, and western falsehellebore were examined for seasonal variation of their contained poisons. With the exception of low larkspur, greatest concentrations of the poisons were found in the leaves. Alkaloid concentration in tall larkspurs decreased with plant maturity. Cattle losses may be reduced if tall larkspurs are avoided during early vegetative growth. The alkaloid content of tall larkspurs was increased by treatment with 2,4,5-T and silvex. Only 2,4,5-T increased alkaloid content of western falsehellebore.