Occurrences of Trans ‐Aconitate in Range Forage Species 1

Young plants of 94 separate species collected largely from hypomagnesemia (grass tetany) prone rangelands during late fall, winter, and early spring, have been analyzed for total aconitate. Species containing 1% or more of their dry weight as aconitate have been classed as accumulators. Forty‐seven percent of the grasses and 17% of the nongrass species fell in the high level category. The spread between individual species was very large (0.05 to 12.4%). Of the two aconitate stereoisomers, cis ‐aconitate was low in all species whereas trans ‐aconitate built up in the accumulators. Levels of trans ‐aconitate fell rapidly with the onset of warming spring weather and higher growth rates. Mowings of mixed plant species reflected the aconitate characteristics of accumulator species. Substantial differences in trans ‐aconitate levels may occur in roots, stems, and leaves of the same plant.