Bigelow sagebrush

Artemisia petrophila Wooton & Standley; Seriphidium bigelovii (A. Gray) K. Bremer & Humphries

Shrubs, 20–40(–60) cm (branched from bases, rounded), mildly aromatic; not root-sprouting. Stems silvery, canescent (bark gray-brown). Leaves persistent, light gray-green; blades narrowly cuneate, 0.5–3 × 0.2–0.5 cm, entire or 3(–5)-lobed (lobes 1.5–2 mm, less than ¹/3 blade lengths, acute), faces silvery canescent. Heads (usually nodding) in arrays 6–25 × 1–4 cm (branches erect, somewhat curved). Involucres globose, 2–3 × 1.5–2.5 mm. Phyllaries (8–15) ovate, canescent or tomentose. Florets: pistillate 0–2 (raylike, laminae to 1 mm); bisexual 1–3; corollas 1–1.5 mm (style branches of ray florets elongate, exsert, epapillate, tips acute; of disc florets, short, truncate, papillate). Cypselae (ellipsoid, 5-ribbed) 0.8–1 mm, glabrous. 2n = 18, 36, 72.

Flowering early summer–late fall. Deserts, sandy or alkaline soils, rock outcrops; 1000–2500 m; Ariz., Calif., Colo., Nev., N.Mex., Tex., Utah.

Artemisia bigelovii of the southwestern deserts is easily confused in the field with A. tridentata, even though it is well distinguished ecologically and morphologically. Systematic placement within subg. Tridentatae remains problematic. Presence of "ray" florets (though rare) and vestigial spines on the pollen (R. P. Wodehouse 1935) suggest a relationship with groups ancestral to Tridentatae. The species also has the unusual characteristic of lignified trichomes (L. M. Shultz 1986b). Further research may help to determine proper placement; its affinities may be with members of subg. Artemisia.