Trees or shrubs evergreen, monoecious; branchlets arranged in a plane, flattened. Leaves 4-ranked, scalelike, base decurrent only on leading branchlets, dimorphic along branchlets: facial pairs obovate-rhombic; lateral pairs boat-shaped, ridged abaxially, less than 4 mm, overlapping facial pairs, without conspicuous, white stomatal bands abaxially. Pollen cones with (4 or)6-10(-16) microsporophylls, each with (2 or)3 or 4 pollen sacs. Seed cones terminal, solitary, dehiscent when mature in 1st year; cone scales 8 or 10, decussate, flat, only middle, larger 2 or 3 pairs fertile, each fertile scale bearing 1 or 2 seeds; free bract apex a very short mucro. Seeds flat, with 2 lateral, narrow wings. Cotyledons 2.
Trees evergreen, small to large. Branchlets flattened, in fan-shaped, flattened, frondlike sprays. Leaves opposite in 4 ranks. Adult leaves heteromorphic; those on larger branchlets with sharp, erect, free apices to ca. 2 mm; those on flattened lateral branchlets crowded, appressed, scalelike, lateral pairs keeled, facial pairs flat; abaxial glands present or absent. Pollen cones with 2--6 pairs of sporophylls, each sporophyll with 2--4 pollen sacs. Seed cones maturing and opening first year, ellipsoid, (6--)9--14(--18) mm; scales persistent, 4--6 pairs, overlapping, oblong and basifixed, thin and woody, 2--3 central pairs fertile, uniformly thin or with slightly enlarged apex, remaining scales sterile. Seeds 1--3 per scale, lenticular, equally 2-winged; cotyledons 2. x = 11.
"Female cones oblong-ovoid, leathery or woody, with 4–6 pairs of overlapping scales, the upper and lower scales sterile, the middle ones each with 2–3 ovules; seeds winged; microsporophylls few; monoecious trees with shreddy bark and small, appressed, imbricate, scale-like, decussately opposite lvs, the lateral ones folded, the upper and lower flat and with a prominent resin-gland, branchlets numerous from the axils of the lateral lvs, forming soft, flat sprays. 6, N. Temp."
|Arborvitae, thuya, cèdre [Greek name for some evergreen, resinous trees]|