Sp. Pl. 2: 1002. 1753; Gen. Pl. ed. 5, 435, 1754.
Trees or large shrubs evergreen. Branchlets terete or quadrangular, in decussate arrays (or partially comblike in Cupressus macnabiana). Leaves opposite in 4 ranks. Adult leaves appressed to divergent, scalelike, rhomboid, free portion of long-shoot leaves to 4 mm; abaxial gland present or absent. Pollen cones with 4–10 pairs of sporophylls, each sporophyll with 3–10 pollen-sacs. Seed-cones maturing in 1–2 years, generally persisting closed many years or until opened by fire, globose or oblong, 1–4 cm; scales persistent, 3–6 pairs, valvate, peltate, thick and woody. Seeds 5–20 per scale, lenticular or faceted, narrowly 2-winged; cotyledons 2–5. x = 11.
Warm north temperate regions
The genus Cupressus in North America consists mainly of small, disjunct, relictual populations, many differing from related populations in color and size of leaves and seeds, activity of leaf glands, glaucousness of various parts, form of growth, and characteristics of bark. Disagreements on the number and rank of taxa reflect these variations. This treatment, with seven taxa, approaches the more conservative end of a spectrum; anywhere from 6 to 15 taxa—species, subspecies, and varieties—might be accepted in the flora. The taxonomy of the genus would benefit from detailed studies of variation in and among populations (cf. J. F. Goggans and C. E. Posey 1968).
The Mediterranean Cupressus sempervirens Linnaeus, usually with a fastigiate habit, is commonly cultivated in California, often away from dwellings, but it does not appear to have become naturalized. Other introduced Eurasian and Mexican species are clearly associated with cultivated landscapes.
Species 10–26 (7 in the flora).
|1||Most leaves with conspicuous, pitlike, abaxial gland.||> 2|
|1||Most leaves without conspicuous, pitlike, abaxial gland, some with inconspicuous shallow or embedded gland.||> 5|
|2||Branchlets comblike.||Cupressus macnabiana|
|2||Branchlets decussate.||> 3|
|3||Branchlets less than 1.3 mm diam.; seed cones mostly 1-2 cm, with scales covered with resin blisters; seeds 3-4 mm.||Cupressus bakeri|
|3||Branchlets 1.3 mm diam. or more; seed cones mostly 2-3 cm, with scales smooth or with scattered resin blisters; seeds 4-6 mm.||> 4|
|4||Leaves rarely resin-dotted; c coastal California.||Cupressus sargentii|
|4||Leaves resin-dotted; interior s California to Texas.||Cupressus arizonica|
|5||Seed cones 1-2.5(-3) cm.||> 6|
|5||Seed cones (2-)2.5-4 cm.||> 7|
|6||Leaves often glaucous; branchlets (1.5-)2-2.5 mm diam.; seeds 4-6 mm.||Cupressus sargentii|
|6||Leaves not glaucous; branchlets 1-1.5 mm diam.; seeds 3-4(-5) mm.||Cupressus goveniana|
|7||Seed cones oblong; bark fibrous, branchlets 1.5-2 mm diam.||Cupressus macrocarpa|
|7||Seed cones globose; bark smooth, branchlets 1-1.5 mm diam.||Cupressus guadalupensis var. forbesii|