Cedar (Cedrus) is a genus of coniferous trees in the plant family Pinaceae. They are most closely related to the Firs (Abies), sharing a very similar cone structure. They are native to the mountains of the western Himalaya and the Mediterranean region, occurring at altitudes of 1,500–3200 m in the Himalaya and 1,000–2,200 m in the Mediterranean.
Cedars are trees up to 30–40 m (occasionally 60 m) tall with spicy-resinous scented wood, thick ridged or square-cracked bark, and broad, level branches. The shoots are dimorphic, with long shoots, which form the framework of the branches, and short shoots, which carry most of the leaves. The leaves are evergreen and needle-like, 8–60 mm long, arranged in an open spiral phyllotaxis on long shoots, and in dense spiral clusters of 15–45 together on short shoots; they vary from bright grass-green to dark green to strongly glaucous pale blue-green, depending on the thickness of the white wax layer which protects the leaves from desiccation. The seed cones are barrel-shaped, 6–12 cm long and 3–8 cm broad, green maturing grey-brown, and, as in Abies, disintegrate at maturity to release the winged seeds. The seeds are 10–15 mm long, with a 20–30 mm wing; as in Abies, the seeds have 2–3 resin blisters, containing an unpleasant-tasting resin, thought to be a defense against squirrel predation. Cone maturation takes one year, with pollination in autumn and the seeds maturing the same time a year later. The pollen cones are slender ovoid, 3–8 cm long, produced in late summer and shedding pollen in autumn.
The treatment of the Turkish, Cyprus and Atlas Cedars as varieties or subspecies of Lebanon Cedar is found primarily in botanical and floristic works, while treatment as separate species is more widespread in popular horticultural use, but also in some botanical works. The discrepancy in treatment derives largely from the very narrow gene base of trees in cultivation, which gives a false impression of distinctiveness of the taxa, not borne out when the wider range of variation found in wild trees is examined. The Deodar Cedar is more distinct and almost universally accepted as a separate species, though very rarely, it has also been treated as a subspecies of Lebanon Cedar, C. libani subsp. deodara (Roxb.) P.D.Sell, thus regarding the genus as comprising a single species.
Cedars are very popular ornamental trees, widely used in horticulture in temperate climates where winter temperatures do not fall below about −25 °C. The Turkish Cedar is slightly hardier, to −30 °C or just below. Extensive mortality of planted specimens can occur in severe winters where temperatures do drop lower. Areas with successful long-term cultivation include the entire Mediterranean region, western Europe north to the British Isles, southern Australia and New Zealand, and southern and western North America.
They are also grown for their durable (decay-resistant) scented wood, most famously used in the construction of King Solomon's temple in Jerusalem provided by King Hiram, or Ahiram, of Tyre, Lebanon, circa 1000 BC. The wood is also used for humbler purposes requiring resistance to weather, such as shakes and shingles. Cedar wood and cedar oil is known to be a natural repellent to moths, hence cedar is a popular lining for modern-day closets in which woolens are stored. The use of cedar is mentioned in The Iliad Book 24, referring to the cedar-roofed or lined storage chamber where Priam goes to fetch the treasures used to ransom the corpse of his son Hector from Achilles.
The name "cedar" has more recently (since about 1700) been applied to many other trees with scented wood (in some cases with the botanical name alluding to this usage). Such usage is regarded by some authorities as a misapplication of the name to be discouraged.