Trees dioecious, to 20 m, single-stemmed (rarely multistemmed); crown conic to occasionally rounded. Bark brown, exfoliating in thin strips, that of small branchlets (5–10 mm diam.) smooth, that of larger branchlets exfoliating in plates. Branches spreading to ascending; branchlets erect to flaccid, 3–4-sided in cross section, ca. 2/3 or less as wide as length of scalelike leaves. Leaves light to dark green but often glaucous blue or blue-gray, abaxial gland elliptic, conspicuous, exudate absent, margins entire (at 20× and 40×); whip leaves 3–6 mm, not glaucous adaxially; scalelike leaves 1–3 mm, not overlapping to overlapping by not more than 1/5 their length, keeled to rounded, apex obtuse to acute, appressed or spreading. Seed cones maturing in 2 years, of 2 distinct sizes, generally with straight peduncles, globose to 2-lobed, 6–9 mm, appearing light blue when heavily glaucous, but dark blue-black beneath glaucous coating when mature (or tan beneath glaucous coating when immature), resinous to fibrous, with (1–)2(–3) seeds. Seeds 4–5 mm. 2n = 22.
Habitat: Rocky soils, slopes, and eroded hillsides
Elevation: 1200–2700 m (0 m at Vancouver Island and Puget Sound)
Alta., B.C., Ariz., Colo., Idaho, Mont., Nebr., Nev., N.Mex., N.Dak., Oreg., S.Dak., Utah, Wash., Wyo., n Mexico.
Juniperus scopulorum hybridizes with its eastern relative J. virginiana in zones of contact in the Missouri River basin (C. W. Comer et al. 1982) and with J. horizontalis (J. × fassettii Boivin; N. C. Fassett 1945). Relictual hybridization with J. virginiana is known in the Texas panhandle (R. P. Adams 1983).