Erigeron flagellaris A. Gray var. trilobatus Maguire ex Cronquist, Brittonia 6: 258. 1947; E. proselyticus G. L. Nesom

Basal leaves: blades (2–)3–5(–11) mm wide, margins usually entire or dentate, rarely deeply lobed. Ray corollas drying pink to dark blue. 2n = 18.

Flowering Jul–Sep. Limestone cliff bases and faces, crevices, ledges, shelves, soil accumulations, talus, limestone gravel, lakeshores, bristlecone pine, spruce-fir-aspen, aspen, limber pine, Engelmann spruce; of conservation concern; 2200–3100 m; Utah.

The leaves of var. sionis tend to be narrower and more deeply lobed than those of var. trilobatus; morphologic intermediacy makes these plants hard to separate even at varietal rank. Differences in habitat and an essentially allopatric distribution, however, suggest that two evolutionary entities are present.