Two-Grooved Milkvetch (Astragalus bisulcatus).
This is an obligate selenium accumulator that, in addition to being capable of containing very high concentrations of selenium, also contains toxins that cause locoism. Two-grooved milkvetches are leafy-stemmed, perennial plants forming large clumps that reach 3 ft in height. Stems are purple in mature plants. The leaves are pinnate with numerous paired hairy leaflets. Flowers are in dense spike-like racemes, generally purple in color but varying from pink to white. The fruit is a leguminous, heavily-textured pod about 1/2 inch (11 to 15 mm) in length. The pod has two characteristic longitudinal grooves on the upper surface, which gives this milkvetch its name. It typifies the 24 or more species of Astragalus that grow on the alkaline seleniferous soils of the western states.
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