Porter mugwort

Perennials or subshrubs, (7–)8–14 cm (cespitose), faintly aromatic. Stems 5–8, silver-gray, densely tomentose. Leaves persistent, silver-green, mostly basal; proximalmost blades 3–4 × 1–1.5 cm, 1-pinnately lobed, lobes mostly 2–3 mm wide; blades of flowering stems somewhat reduced, (1–)2–3(–5) × 0.15 cm, mostly entire; apices rounded, faces densely hairy. Heads borne singly or (clustered in 2s and 3s on lateral branches; peduncles 0 or to 5 mm) in paniculiform arrays, (2–)4–9 × 1–1.5(–2) cm. Involucres broadly campanulate, 4–5(–7) × 2–3 mm. Phyllaries (ovate, margins broadly scarious) densely tomentose. Florets: pistillate 8–10 (2–2.8 mm); functionally staminate 22–32; corollas pale yellow, 2.2–4.5 mm, glandular. Cypselae (light brown) ellipsoid, flattened (faintly nerved), 1.5–2 mm, sparsely hairy, glabrous or resinous.

Flowering mid–late summer. Barren clay and gravelly soils; 1800–2000 m; Mont., Wyo.

Although Cronquist observed that Artemisia porteri may be an autopolyploid derivative of A. pedatifida, morphologic similarities to northerly cespitose taxa suggest a more complex origin.

Artemisia porteri is in the Center for Plant Conservation’s National Collection of Endangered Plants.