A
monoecious tree, it is small, slow-growing, reaching 15–20 m (49–66 ft) and 0.5 m (1 ft 8 in) trunk diameter (exceptionally to 30 m or 98 ft tall and 2 m or 6 ft 7 in diameter in very old trees). The foliage forms in flat sprays with scale-like
leaves 2–4 mm (0.08–0.16 in) long, which are
bright green in colour but may turn brownish or
coppery orange in winter. The
cones are 1.5–2.5 cm (5⁄8–1 in) 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 (0.16–0.24 in) long, with no wing.[citation needed]
The branches are relatively short, loosely arranged and, usually, sharply directed upwards, and the bark, brownish, is detached in narrow vertical strips. The twigs are compressed and are arranged in vertical planes. The leaves, arranged in four rows, fleshy, opposite,
decussate, truncated, imbricated as adults, somewhat curved inwards, of uniform green color and with a resiniferous gland on the underside. The female cones, of pink-salmon color and later bluish-greenish when immature, centimetric and of annual maturation, are oval with 6-8 flattened, thick scales,
coriaceous and provided with an apical hook.[7]
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.
Etymology
The binomial Platycladus means "with broad or flattened shoots" deriving from Greek πλατύςplatys "broad, flat, level" and κλάδοςklados "branch, shoot of a tree".[8] The qualifier orientalis refers to its native habitat in China.[9]
Distribution
It is native to
northwestern China, but it is difficult to distinguish the areas where they are native safely from those where they have been introduced. It is distributed in
Manchuria,
Russian Far East (
Amur and
Khabarovsk), and now it is naturalised in
Korea,
Japan,
India,
Florida and
Iran as well. It is also cultivated in many parts of the world in parks, gardens, home
yards, cemeteries and for
hedges.[10]
Uses
Resistant to drought, it is very often used as an ornamental tree, both in its homeland, where it is associated with long life and vitality, and very widely elsewhere in
temperate climates. It is suitable for form cuts and year-round opaque
hedges, but also forms impressive slender solitary trees. Several
cultivars have been selected, of which 'Aurea Nana'[11] has gained the
Royal Horticultural Society's
Award of Garden Merit.[12]
The wood is used in Buddhist temples both for (lavairos) construction work, and chipped, for
incense burning. Its twigs and leaves contain 0.12% essential oil containing
pinene and probably
caryophyllene.[13] Its use as a memorial tree dates back to the
Zhou dynasty in China, where it was the official memorial tree of princes.[14]
^USDA, NRCS (n.d.).
"Platycladus orientalis". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 7 October 2015.
^Harrison, Lorraine (2012). RHS Latin for gardeners. United Kingdom: Mitchell Beazley. p. 224.
ISBN9781845337315.
^Armin Jagel, Veit Martin Doerken: Morphology and morphogenesis of the seed cones of the Cupressaceae - part II: Cupressoideae. Bull. CCP 4 (2), 2015, pp. 51-78
^Armin Jagel, Thomas Stützel: Studies on the morphology and morphogenesis of the seed cones of Platycladus orientalis (L.) Franco (= Thuja orientalis L.) and Microbiota decussata Kom. (Cupressaceae) . Bot. Year syst. Bd. 123, 2001, pp. 337-404.