Platycladus is a monotypic taxon genus of evergreen Pinophyta trees in the cypress family Cupressaceae, containing only one species, Platycladus orientalis, also known as Chinese thuja,
Description
A
monoecious tree, it is small, slow-growing, reaching and trunk diameter (exceptionally to tall and diameter in very old trees). The foliage forms in flat sprays with scale-like
leaves long, which are bright green in colour but may turn brownish or coppery orange in winter. The
conifer cone are long, green ripening brown in about eight months from pollination, and have 6–12 thick scales arranged in opposite pairs. The
are long, with no wing.
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.[ Kremer BP, Trees, Editorial Blume, Barcelona, 1986, Thuja orientalis L., p. 78]
Taxonomy
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
grafting 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 πλατύς
platys 'broad, flat, level' and κλάδος
klados 'branch, shoot of a tree'.
[, .] The qualifier
orientalis refers to its native habitat in China.
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 Oblast 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
.
[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]
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
temperateness climates. It is suitable for form cuts and year-round opaque
, but also forms impressive slender solitary trees. Several
cultivars have been selected, of which 'Aurea Nana'
has gained the Royal Horticultural Society's Award of Garden Merit.
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.[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.] Its use as a memorial tree dates back to the Zhou dynasty in China, where it was the official memorial tree of princes.
Gallery
General references
