Calocedrus decurrens, commonly referred to as the California incense cedar (syn. Libocedrus decurrens), is native to western North America, and is present in the San Bernardino Mountains. It ranges from King County in Washington, through central western Oregon and most of California as well as Washoe County the extreme west of Nevada, and also a short distance into northwest Mexico in northern Baja California.
Calocedrus decurrens is an aromatic evergreen conifer with upright branching that is narrow-columnar in youth but may broaden with age to conical sometimes with a rounded crown
It is a large tree, typically reaching heights of 130 to 200 feet and a trunk diameter of around nine feet, with a broad conic crown of spreading branches. The leaves are bright green on both sides of the shoots, and the tree sports solitary fruiting cones around an inch long, which ripen in summer at the branchlet ends. Although small, the cones are very distinctive and are commonly described as resembling duckbills when they open to release their seed.
The California incense cedar is by far the most widely known species in the genus, and is often simply called “incense cedar” without the regional qualifier. This tree is the preferred host of a wood wasp, Syntexis libocedrii which lays its eggs in the smoldering wood immediately after a forest fire. The epithet decurrens is the present participle of dēcurrō, meaning running or flowing down.
These trees can live for more than 1,000 years.
The wood of Calocedrus is soft, moderately decay-resistant, and with a strong spicy-resinous fragrance. That of C. decurrens is the primary material for wooden pencils, because it is soft and tends to sharpen easily without forming splinters.
Calocedrus decurrens, particularly outside of California, is a popular ornamental tree, grown in locations with cool summer climates like Britain, Washington and British Columbia. Its very narrow columnar crown in landscape settings, an unexplained consequence of the climatic conditions in these areas, is not shown by trees in their native ‘wild’ habitat. In cultivation, these trees typically grow shorter, at 30 feet to 50 feet tall. Flattened branchlets in fern-like sprays are covered with overlapping, lustrous, rich green, scale-like foliage in whorls of four. Its foliage has an incense-like aroma when crushed. Reddish-brown, deeply-furrowed, scaly bark appears on mature trees. Synonymous with and formerly known as Libocedrus decurrens.
The incense-cedar is an important component of mixed-conifer forests, such as in white fir (Abies concolor) forests at the upper margin of the mixed-conifer zone in southwestern Oregon and northern California and giant sequoia (Sequoiadendron giganteum) groves in the Sierra Nevada mixed-conifer zone of California. Incense-cedar occurs with bigcone Douglas-fir (P. macrocarpa) in southern California [140] and with Jeffrey pine (Pinus jeffreyi) and ponderosa pine (Pinus ponderosa var. ponderosa). It grows with ponderosa pine, Jeffrey pine, sugar pine (P. lambertiana), and white fir throughout much of its range, as incense-cedar and Jeffrey pine are common associates on serpentine soils. It also extends into the chaparral zone.
The genus name comes from the Greek words kalos meaning beautiful and cedrus meaning cedar tree.
In its native habitat, the California incense cedar has no serious insect or disease problems, though heart rot and rust may occur in some areas. These trees flourish in deep, moderately fertile, moist but well-drained loams in full sun to part shade. While they do best in soils that do not fully dry out and they appreciates a location protected from drying winter winds, the California incense cedar is nevertheless valued for its drought tolerance and it tolerates shearing.