Leaves narrowly cuneate (5-10 × 3-6 mm, lobed, lobes ¹/2+ blade lengths, laterals to 1 mm wide, often acute). Involucres (1.5-)2-2.5 × 1.5-2 mm.

Flowering mid-late summer. Rocky soils of igneous origin; 2200-2500 m; Idaho, Utah, Wyo.

Because of its deeply lobed leaves, subsp. thermopola can be confused with Artemisia tripartita. The habit, leaf morphology, and geographic distribution of subsp. thermopola suggest introgression between typical A. arbuscula and A. tripartita.