8c. Ranunculus acriformis var. aestivalis L. D. Benson, Amer. Midl. Naturalist. 40: 250. 1948.
Ranunculus acris Linnaeus var. aestivalis (L. D. Benson) S. L. Welsh; R. aestivalis (L. D. Benson) R. Van Buren & K. T. Harper
Stems hirsute. Flowers: receptacle obpyriform to cylindric; sepals reflexed ca. 2 mm above base, pubescence of spreading hairs; petals 8-11 mm. Achenes: beak 0.4-1 mm.
Flowering summer (Jul-Sep). Meadows; 2100-2900 m; of conservation concern; Utah.
Ranunculus acriformis var. aestivalis is known from two sites in southern Utah, a saline meadow south of Panguitch in the Sevier River Valley and a riparian meadow in Boulger Canyon, Emery County. R. Van Buren et al. (1994) treated this variety as a distinct species, R . aestivalis , emphasizing the saline habitat of the Sevier Valley population. The morphologic differences between R . acriformis var. aestivalis and the other varieties of R . acriformis are minor, and the habitat of the single Emery County specimen is typical of the species. I prefer to retain this taxon in R . acriformis . The DNA data of Van Buren et al., based on a total of eight populations of the three varieties, are consistent with either interpretation, because the three varieties form a single clade with R . acriformis var. aestivalis as sister group to the other two.
Van Buren, R., K. T. Harper, W. R. Andersen, D. J. Stanton, S. Seyoum, and J. L. England. 1994. Evaluating the relationship of autumn buttercup (Ranunculus acriformis var. aestivalis) to some close congeners using random amplified polymorphic DNA. Amer. J. Bot. 81: 514-519.