Calocedrus decurrens

Incense cedar


The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivision - Spermatophyta (seed plants). Division - Coniferophyta (conifers). Class - Pinopsida. Order - Pinales. Family - Cupressaceae (cypress). Genus - Calocedrus Kurz. Species - Calocedrus decurrens (Torr.) Florin

Ecology: Incense-cedar is shade tolerant. Seedlings establish readily in shade, and trees persist in the shaded understory for long periods. In many stands, incense-cedar is an important component of both the understory and the overstory. It occupies a "subdominant" crown position in several forest types. Incense-cedar is an important component of mixed-conifer forests in southern Oregon, California, and northern Baja California. Incense-cedar is also common 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. In Sierra Nevada mixed-conifer forests it may account for half of the stems in a stand. Incense-cedar occurs with bigcone Douglas-fir (P. macrocarpa) in southern California and with Jeffrey pine (Pinus jeffreyi) and ponderosa pine (Pinus ponderosa var. ponderosa) throughout much of its range. Incense-cedar and Jeffrey pine are common associates on serpentine soils. On the east side of the Oregon Cascade Range, incense-cedar occurs in dry ponderosa pine forests. On the eastern slope of the Sierra Nevada, it grows with ponderosa pine, Jeffrey pine, sugar pine (P. lambertiana), and white fir. Incense-cedar grows with Oregon white oak (Quercus garryana) and California black oak (Q. kelloggii) in southern Oregon and California. It is a minor associate in canyon live oak (Q. chrysolepis) forests and may also extend into the chaparral zone in California.


Trees to 57 m; trunk to 3.6 m diam. Bark cinnamon brown, fibrous, furrowed and ridged. Branchlet segments mostly 2 or more times longer than wide, broadening distally. Leaves 3--14 mm, including long-decurrent base, rounded abaxially, apex acute (often abruptly), usually mucronate. Pollen cones red-brown to light brown. Seed cones oblong-ovate when closed, red-brown to golden brown, proximal scales often reflexed at cone maturity, median scales then widely spreading to recurved, distal scales erect. Seeds 4 or fewer in cone, 14--25 mm (including wings), light brown.


Fire effects: Young incense-cedar trees are usually killed by fire due to thin bark and flammable crowns. They often have branches that reach to the ground and are therefore likely to torch. Mature incense-cedars have thick bark and are more fire resistant than young trees. Mature trees may survive or be killed by fire, depending on the severity of the fire. Incense-cedars growing on moist, protected sites are likely to survive fire. Postfire regeneration is by seeds dispersed in the first postfire year or later by parent trees that survive the fire and by seeds from off-site sources.

Pests and pathogens: Incense-cedar is highly susceptible to pocket dry rot, particularly in the mild, western portions of incense-cedar's range. Pocket dry rot is most prevalent in trees >150 years old and commonly enters the tree through fire scars and the wounds caused by broken branches. An estimated 81% of pocket dry rot infections enter through fire scars. Incense-cedar is susceptible to a variety of other pathogens including annosus root disease (Heterobasidion annosum), the trunk rot fungus Oligoporus amarus, incense-cedar rust (Gymnosporangium libocedri), and the western conifer seed bug (Leptoglossus occidentalis). Incense-cedar mistletoe (Phoradendron libocedri) is common in incense-cedar crowns. Incense-cedar is occasionally infested with mountain pine beetles (Dendroctonus ponderosae), but the beetles rarely produce broods in incense-cedar.


Flowering and fruiting - Male cones are terminal on twigs and reach a length of 4 to 7 mm. Female cones develop on the ends of the previous year's growth and reach 1.4-4 cm at maturity. They contain 4 or fewer seeds. Seeds are 8 to 12 mm long and have 2 wings of unequal length. Incense-cedar is monoecious, wind pollinated, and seeds are wind dispersed...Because the seeds are light and have a large wing averaging 2.5 cm in length, they fall slowly (1.8 m/s in still air) and may be carried great distances by wind. Incense-cedar seeds germinate well on bare soil and in light litter. Seeds can also germinate on a well-developed duff layer. Incense-cedar seedlings can establish in shade and in heavy litter or brush cover.

Vegetative regeneration - Incense-cedar does not reproduce vegetatively.

Species Distribution


USDA Plants Database
USDA, NRCS. 2016. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.

USFS Plant Database
Habeck, R. J. 1992. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

Flora of North America
Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 19+ vols. New York and Oxford.

The Jepson Herbarium
The Jepson Manual: Vascular Plants of California. B.G. Baldwin, D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken [editors]. 2012. 2nd edition, thoroughly revised and expanded. University of California Press, Berkeley, CA.

USGS Plant Species Range Maps
Critchfield, W.B., and Little, E.L., Jr., 1966, Geographic distribution of the pines of the world: U.S. Department of Agriculture Miscellaneous Publication 991, p. 1-97. Little, E.L., Jr., 1971-1978, Atlas of United States trees, volume 1,3,13,17, conifers and important hardwoods: U.S. Department of Agriculture Miscellaneous Publications.