Cedrus is a genus of four species found in three disjunct areas: the Atlas Mountains of North Africa; mountainous parts of the eastern Mediterranean, including Turkey, Lebanon and Cyprus; and the Hindu Kush, Karakoram and Himalayan mountain ranges. Cedars are generally large, evergreen trees with straight, columnar trunks (though often forked or multistemmed). The bark is thin, grey-brown, later darkening and cracking into small plates. Young plants are conical, with regular branching, although as they mature several first-order branches may become co-dominant with the main stem (especially in C. libani subsp. libani); in C. deodara, however, apical dominance is usually maintained, which may account for this reaching the tallest heights among the cedar species. The branchlets have marked dimorphism: leading shoots are long and slender, lateral shoots short and stunted (‘short shoots’); vegetative buds are not resinous or only slightly so. The leaves are needle-like, dark green or glaucous-blue, rigid, spirally arranged, slightly narrow at the base, the apex acute. The male strobili are erect, solitary, catkin-like, terminating short shoots, and thus subtended by a whorl of leaves. The female cones are erect, also positioned on short shoots, less abundant than the strobili, but both are usually located on the outer branches, around the crown; the cones mature in the second year (after 17–18 months), glaucous-green turning dull brown. The seed scales are broad, somewhat papery, subtended by insignificant bract scales, spirally arranged around the central rachis; at maturity the scales fall to leave the rachis. Seeds are borne two per scale, partially enclosed in a membranous cup, which extends to form a wing. There appear to be few morphological characters to separate the species of cedar, though habit characteristics are useful with cultivated material (Farjon 1990).
From Bean's Trees & Shrubs
A group of three, or, if the Cyprian cedar be regarded as more than a variety, four species of evergreen trees, forming a very homogeneous group. They are as closely allied to each other as they are markedly distinct from other coniferous trees. Sir Joseph Hooker and other authorities regarded them all as geographical forms of one species. In a recent study, Schwartz recognises two species: C. deodara and C. libani, which he subdivides into four subspecies, viz. subsp. libani, stenocoma (q.v. under C. libani), brevifolia, and atlantica (Fedde's Repertorium, Vol. 54 (1), p. 26). Most closely allied to them are the larches, deciduous though these are. Given space for lateral development, old cedars become flat-topped, and their branches grow horizontally. As in the larches and some other conifers, the branchlets are of two kinds: (1) leading ones, which grow considerably (at least several inches) during the summer, and bear the leaves singly and spirally arranged; and (2) short, spur-like ones, which lengthen a fraction of an inch only per annum, and have the leaves crowded in a dense tuft at the end. The latter kind are capable of developing into the former. Flowers of both sexes appear on the same tree, usually on the upper side of the branches. Males very densely set in erect, finger-shaped cones, 2 to 3 in. long, 1⁄2 to 5⁄8 in. wide, shedding clouds of yellow pollen when ripe. Females in stout, erect cones, purplish at first, ultimately 3 to 5 in. long, flat or depressed at the top, the scales broad and closely overlapping; seeds winged.
The cedars all like a deep loamy soil, well drained but moist. They are admirably adapted for growing as specimen trees on lawns, and for this purpose should be planted when not more than 4 to 6 ft high. It is necessary to propagate some of the garden varieties by grafting on their typical forms, but they are of little importance. Trees raised from seed will always grow better and give the greater pleasure.
The timber of all the cedars as produced on their native mountains is valuable, but as grown in our milder, softer climate, it is not so hard and durable. The timber of English-grown Lebanon cedar is sometimes handsomely grained, and may be used for indoor purposes.