Calocedrus contains three species: C. decurrens on the Pacific coast of North America, and C. macrolepis and C. formosana, in China and Taiwan, respectively. The genus was formerly included in Libocedrus (as in Bean 1981a), together with Austrocedrus, Papuacedrus and Pilgerodendron. Calocedrus species are large evergreen trees with a broadly conical or columnar habit. In some parts of eastern Britain the habit of C. decurrens becomes tightly fastigiate with very short branches, though the reasons for this change are unknown. The bark is initially smooth, becoming scaly or breaking into longitudinal plates; colour varies from white to purplish grey. Major branches are spreading to ascendant. Branchlets are dorsiventrally flattened, and fan-shaped. The leaves are in pairs, scale-like, appressed, decussate, strongly dimorphic in shape and size; the lateral pair overlapping the facial pair. Male and female cones are produced on different branches on the same tree. The male strobili are oblong, with 12–16 decussate scales; the female cones erect or pendulous, yellowish to reddish brown, ellipsoidal, mature in the first year. The seed scales are thin, woody, with a small, spiny umbo, in (two to) three decussate pairs; the distal pair is connate and sterile, the median pair fertile, the proximal pair reduced or absent. Each scale bears one to two lenticular seeds, each with one short, rudimentary wing and one long, fully formed wing (Watson & Eckenwalder 1993, Li & Keng 1994c, Fu et al. 1999e).
The Californian Calocedrus decurrens is a justly popular tree, with a delicious fragrance when the shoots are crushed. The famous group of columnar specimens at Westonbirt, familiar to dendrologists from their portrait on the jacket of ‘Bean, Volume Two’, have also been accorded the accolade of a plate in Thomas Pakenham’s Meetings with Remarkable Trees (Pakenham 1996). Perhaps in consequence of these images the species is often thought to be strictly columnar but this is not usually the case, and a much more relaxed outline is normal. This tree is usually found as a native in summer-dry situations, but the Asian species are found in moister forest. Planting sites should be chosen accordingly.
From Bean's Trees & Shrubs
A genus of three species of trees, one in western North America, the other two (closely related to each other) in eastern Asia. Leaves scale-like, decussate, appressed except at the tip. Branchlets flattened, arranged in sprays. Female cones with six scales, each with a small mucro on the back near the apex, the lowermost pair small, sterile, the next pair fertile, the uppermost pair sterile, narrow, united into a plate. Seeds two to each fertile scale, unequally two-winged. See further in Volume II, pages 564-5 and also under Libocedrus in this supplement.