Trees to more than 20 m tall; trunk to 1 m (or more) d.b.h.; bark reddish brown to light grayish brown, thin, flaking in long strips; crown ovoid-pyramidal when young, broadly rounded or irregular when old. Leaves 1-3 mm, apex bluntly pointed; facial leaves rhomboid, with a conspicuous, linear, glandular groove at center abaxially; lateral leaves overlapping facial
ones, boat-shaped, ridged, apex slightly incurved. Pollen cones yellowish green, ovoid, 2-3 mm. Seed cones when immature bluish green, subglobose, ca. 3 mm in diam., when ripe reddish brown, subovoid, 1.5-2(-2.5) × 1-1.8 cm; proximal 2 fertile cone scales 2-seeded, distal 2 fertile scales 1-seeded. Seeds grayish brown or purplish brown, ovoid or subellipsoid, 5-7 × 3-4 mm, slightly ridged. Pollination Mar-Apr, seed maturity Oct.
Recorded from China: S Gansu, Hebei, Henan, Shaanxi, Shanxi, Nei Mongol [Inner Mongolia]; Korea; Russian Far East. This species is apparently quite widespread but the geographic and altitudinal range is confused by populations which may have been planted or have become naturalized.
Exploitation for timber of larger trees in natural habitat has caused a decline in the number of mature individuals. How much this has impacted on the total population is difficult to establish due to uncertainty about its natural distribution.
Native in S Gansu, Hebei, Henan, Shaanxi, Shanxi; introduced or status uncertain in Anhui, Fujian, N Guangdong, N Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, S Nei Mongol, Shandong, Sichuan, Xizang, Yunnan, Zhejiang [Korea, E Russia].
Platycladus is a distinct genus of evergreenconiferoustree in the cypress family Cupressaceae, containing only one species, Platycladus orientalis, also known as Chinese arborvitae, biota or oriental thuja. It is endemic to northwestern China. It is also now naturalised as an introduced species elsewhere in Asia: eastward to Korea and Japan; southward to northern India; and westward to northern Iran.
Although generally accepted as the only member of its genus, it has been suggested that the closely related species Microbiota decussata could be included in Platycladus, but this is not widely followed. Other fairly close relatives are Juniperus and Cupressus, both of these genera being graft-compatible with Platycladus. In older texts, Platycladus was often included in Thuja, which is reflected in one of its common names, "oriental thuja". But it is only distantly related to the genus Thuja. Differences include its distinct cones, wingless seeds, and its almost scentless foliage.
The binomial Platycladus means "with broad or flattened shoots". The qualifier orientalis refers to its native habitat in China.
The common name 'arborvitae' is from Latin, 'tree of life', and is based on its association with long life and vitality in Buddhist thought in China. This is probably based on the tree's unchanging evergreen nature in the cold dry climate of northwest China, and its longevity; some of the larger specimens planted around Buddhist temples in China are said to be in excess of 1,000 years old. It is called ce bai (側柏) in Chinese.
It is a small, slow-growing tree, to 15-20 m tall and 0.5 m trunk diameter (exceptionally to 30 m tall and 2 m diameter in very old trees). The foliage forms in flat sprays with scale-like leaves 2-4 mm long. The cones are 15-25 mm long, green ripening brown in about eight months from pollination, and have 6-12 thick scales arranged in opposite pairs. The seeds are 4-6 mm long, with no wing.