D. Isely (1983) regarded the widespread Astragalus wootonii as intergradient with A. allochrous, and the two are sympatric over much of the range of the latter. He placed A. wootonii into A. allochrous as var. playanus. The proposal has merit but merely moves the resolution of the problem of distinction to another level. The plants contain swainsonine and are potentially poisonous to livestock (L. F. James and S. L. Welsh 1992).

Distribution

sw United States, n Mexico.

Discussion

Varieties 2 (1 in the flora).

Variety candollianus (Kunth) Barneby is disjunct in Mexico.

Selected References

None.

Lower Taxa

Astragalus wootonii var. wootonii