Cedrus, commonly known as true cedars, is a small genus of large coniferous trees in the family Pinaceae (subfamily Abietoideae), belonging to the order Pinales. The genus encompasses two to four species depending on taxonomic authority, all native to the mountains of the western Himalayas and the Mediterranean region, where they grow at elevations of 1,000 to 3,200 metres.
Cedars are imposing trees characterised by a tall, cylindrical trunk and a broadly spreading crown. Their leaves are needle-like, growing in dense tufts of 15 to 45 needles, and range in colour from bright green to blue-green with a waxy coating. The cones stand erect on the branches and, when mature, disintegrate on the tree to release the winged seeds; both pollen and seeds are wind-dispersed.
The genus was formally described by the German botanist Christoph Jacob Trew in 1757. The number of accepted species remains a matter of ongoing taxonomic debate. Cedrus deodara, the deodar cedar, is native to the western Himalayas and is considered the sister lineage to the Mediterranean cedars. The Mediterranean group includes Cedrus libani (Lebanon cedar), Cedrus atlantica (Atlas cedar), and Cedrus brevifolia (Cyprus cedar), the last of which is sometimes treated as a variety or subspecies of C. libani rather than a full species. The species are geographically isolated from one another in nature and do not hybridise naturally, though they hybridise freely when grown together in cultivation.
Cedars are adapted to mountainous climates: Mediterranean populations experience winter precipitation (mostly snow) and summer drought, while Himalayan populations receive primarily summer monsoon rainfall with occasional winter snowfall. Cedar wood is naturally scented, durable, and exceptionally decay-resistant, and has been prized for construction of temples and palaces for more than 4,000 years — the longest recorded history of any conifer in sustained human use. Cedarwood oil is naturally repellent to moths and has a long-persistent scent. In the wild, cedars provide habitat for a range of organisms, though they are vulnerable to bark beetles under drought stress and to various fungal pathogens including sirococcus blight.
Cedars are widely planted as ornamental trees in parks and large gardens across temperate climates and are also trained as bonsai.
Etymology
The English name "cedar" derives from Old English ceder, itself from Latin cedrus, which traces to Greek κέδρος (kédros), a word applied to both cedar and juniper. Because kédros does not appear to derive from any Middle Eastern language, it has been suggested the term originally referred to Greek junipers and was later transferred to the genus Cedrus on account of their similarly aromatic woods. The first recorded use of the word in English in its specifically biblical sense of Cedrus dates to around 1000 CE.
Distribution
Cedars are native to the mountains of the western Himalayas and the Mediterranean region. In the Himalayas, they occur at altitudes of 1,500–3,200 m; in the Mediterranean, at 1,000–2,200 m. In Lebanon, a small number of Lebanon cedars survive in protected areas including the Cedars of God near the Qadisha Valley, a UNESCO World Heritage Site.
Ecology
Cedars are adapted to contrasting mountainous climates: Mediterranean populations depend on winter snowfall and endure summer drought, while Himalayan populations rely primarily on summer monsoon rainfall. Cedar trees are generally robust but become vulnerable to bark beetles during drought conditions. Fungal diseases include canker, collar, crown and root rot, needle blight, Gymnosporangium rusts, and sirococcus blight (Sirococcus tsugae). Other pests include the giant conifer aphid, scale insects, pine wilt nematode, and caterpillars of the pine processionary moth.
Cultivation
Cedars are popular ornamental trees suited to temperate climates where winter temperatures remain above −25 °C (the Turkish cedar tolerates down to −30 °C). They are commonly planted in parks and large gardens and are also trained as bonsai in varied styles. When different species are grown together, they hybridise freely in cultivation, making hybrid detection difficult. Hybrids between Atlas and deodar cedars have been deliberately bred since the 1980s, formalised in 2021 as the cultivar group Cedrus Tesi Group.
History
Cedrus wood has been used for building temples and palaces for over 4,000 years — since at least the period of the Epic of Gilgamesh — making it the longest-documented conifer in human use. Genetic and environmental studies corroborate local oral tradition and Hittite cuneiform records indicating that two small isolated populations of Lebanon cedar in northern Anatolia, some 500 km north of the species' main native range, were deliberately planted over 3,200 years ago to supply timber to the Hittite capital at Hattusa.
Taxonomy Notes
The genus Cedrus was described by Christoph Jacob Trew in 1757. The number of recognised species varies from one to four depending on the authority: Cedrus brevifolia (Cyprus cedar), for example, is variously treated as a distinct species, a variety, or a subspecies of C. libani; allozyme evidence suggests it may even fall within the range of variation of Turkish cedar. Cedrus deodara (deodar) is consistently identified as the sister lineage to the Mediterranean cedars. The oldest fossil assignable to the genus is Cedrus penzhinaensis, from Early Cretaceous (Albian) sediments in Kamchatka, Russia.
