Sargent, Gard. & Forest. 10: 420, fig. 54. 1897.
Rocky Mountain juniper, Rocky Mountain redcedar
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. 2 n = 22.
Rocky soils, slopes, and eroded hillsides; 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).