Common Name: Biota

General Information

Platycladus orientalis is a much-branched, evergreen tree with a conical crown when young, becoming broadly rounded or irregular when old; it can grow 20 metres or more tall. The striaght, cylindrical bole can be 100cm or more in diameter[].
A commonly used medicinal herb in China, where the plant is harvested from the wild and also cultivated. The plant is also valued for its wood and is often grown as an ornamental, where it can be used to make a hedge.This is also one of the most commonly planted amenity and ornamental conifers, a tradition that goes back many centuries. It is therefore a common tree in parks of towns and cities in much of temperate Asia[].
This is possibly the most widely introduced cupressaceous conifer in Asia. In many areas inside and outside China it has 'escaped' from cultivation and established spontaneous populations. It is therefore very difficult to establish its natural range but it is likely to be native only in parts of the listed provinces and in a restricted area in Korea and adjacent Russia. The original extent of occurrence of this species, before people planted them everywhere, is much smaller but difficult to establish. From what we know it is likely that mature trees in natural forests are quite rare. The situation in Russia is unknown. Exploitation for timber of larger trees in its 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. The plant is classified as 'Near Threatened' in the IUCN Red List of Threatened Species(2013)[].
In some parts of China (e.g. Yunnan) and in other countries (e.g. Iran) it has probably been naturalized[].

Known Hazards

The essential oil in this plant contains thujone. Thujone is a GABA receptor antagonist which allows neurons to fire more easily. In larger doses this can cause muscle spasms and convulsions, and can also be toxic to brain, kidney, and liver cells.
There has been a lot of negative press regarding thujone, particularly in the mid 19th century when thujone was reported to be more dangerous than alcohol - since shown to be exaggerated; and reports in the 1970’s that it might have a similar effect on the brain to THC (found in cannabis) – since found to be incorrect.
Thujone is probably best known for its use in the alcoholic drink ‘Absinthe’. It is also found in the essential oils of many other plants that are used in herbal medicines and foods, including Arborvitae (Thuja species), some Junipers (Juniperus species), Wormwoods (especially Artemisia absinthium) and Sage (Salvia officinalis). There are some legal restrictions in various countries on the quantity of thujone that can be added to foods and drinks and these vary between countries.
Side effects from consuming thujone can include sleeplessness and anxiety but, unless the pure essential oil is used, the quantity of thujone found in plants is well within safety levels. Pregnant women, however, may be advised to restrict their use of thujone-containing plants.
The leaves are toxic if eaten[]. The plant can also cause skin allergies in sensitive people[].

Botanical References

, ,

Range

E. Asia - Russian Far East, central China, Korea

Habitat

Steep dry rocky valley slopes; at elevations from 300 - 3,300 metres[, ]. Found in the transitional open woodland zone, almost invariably in secondary vegetation or, nearest to its original habitat, in more or less degraded woodland and forest[].

Properties

Weed Potential	Yes
Conservation Status	Near Threatened
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	15.00 m
Growth Rate	Slow
Pollinators	Wind
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Platycladus orientalis grows best in areas with a more continental climate of hot summers and cold winters. It often does not grow well in mild and moist maritime climates. In Britain, the best specimens are to be found in towns or cities away from the west of the country, such as Oxford, and in very sharply drained soils in gardens[].
Prefers a moist loamy soil[]. Grows best on dry freely draining sites, often alkaline in reaction[]. Does well over old building rubble[]. Tolerant of dry dusty sites and of atmospheric pollution in towns[]. Prefers a sunny sheltered position[]. The plant appears to be tolerant of drought, as well as the air pollution that occurs within the urban environment[].
A substantial number of cultivars has been raised in Europe since its introduction to France around 1700, many of which are now obsolete, while new cultivars continue to be selected and described[].
Easily transplanted[].
There are many named varieties selected for their ornamental value.
Produces seed freely in cultivation[].
A slow growing tree[, ].
Plants cannot regenerate from old wood. Pruning is not normally necessary for this species, any pruning that is carried out should be done with care[].
Plants are susceptible to attacks by honey fungus[].
Plants are monoecious, male catkins being produced at the tips of branches and female cones at the base[].
This tree is a favourite with Taoists, Buddhist and Confucian priests, which accounts for its wide spread cultivation. The fresh boughs are sold to worshippers at shrines and temples. Where Platycladus orientalis is abundant, monasteries and temples are never far away[].

Edible Uses

Seed - after removing the bitterness[, ]. No more details are given, but the bitterness in seeds is usually removed either by leaching them in water or by thoroughly cooking them[].

Medicinal

This plant is commonly used in Chinese herbalism, where it is considered to be one of the 50 fundamental herbs[]. Both the leaves and the seeds contain an essential oil consisting of borneol, bornyl acetate, thujone, camphor and sesquiterpenes[]. The leaves also contain rhodoxanthin, amentoflavone, quercetin, myricetin, carotene, xanthophyll and ascorbic acid[].

The leaves are antibacterial, antipyretic, antitussive, astringent, diuretic, emmenagogue, emollient, expectorant, febrifuge, haemostatic, refrigerant and stomachic[, , , ]. Their use is said to improve the growth of hair[, , ]. They are used internally in the treatment of coughs, haemorrhages, excessive menstruation, bronchitis, asthma, skin infections, mumps, bacterial dysentery, arthritic pain and premature baldness[, ].
The leaves are harvested for use as required and can be used either fresh or dried[].
This remedy should not be prescribed to pregnant women[].

The seed is aperient, lenitive and sedative[, , ]. It is used internally in the treatment of palpitations, insomnia, nervous disorders and constipation in the elderly[].

The root bark is used in the treatment of burns and scalds[].

The stems are used in the treatment of coughs, colds, dysentery, rheumatism and parasitic skin diseases[].

Agroforestry Uses:

The tree is being used in afforestation schemes in northeastern China, especially on deforested hills and mountains[]. As a pioneer of relatively dry, open vegetation on often unstable slopes, this species has found abundant opportunity over much of China, and even beyond (e.g. NE Iran), to establish itself and spread after introduction. It is much used in afforestation in NE and Central China and commonly planted in Central Asia[]. A long-lived species, it generally remains as other trees become established[].
Tolerant of regular trimming, though not into old wood, the plant can be grown as a dense hedge[].

Other Uses

A yellow dye is obtained from the young branches[].

An essential oil can be obtained from the leaves and the seeds[].
The foliage is in some parts of China is much used for incense burning, to which purpose the species has been introduced widely outside its natural range[].

The wood is durable in the soil, moderately hard, rather coarse grained, light in weight, soft, brittle. Used for construction, cabinet making, cooperage[, , , ].
The wood is used for building and construction of houses and temples in areas where there are still trees of good size left[].

Propagation

Seed - best sown when ripe in the autumn in a cold frame. Stored seed germinates best if given a short cold stratification. It can then be sown in a cold frame in late winter. Plants make very little growth in their first year[]. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for at least their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts.
If there is sufficient seed it is worthwhile trying a sowing in an outdoor seed bed in mid spring[]. Grow the plants on for at least two years before planting them out in the winter.
Cuttings of half-ripe wood, 5 - 8cm with a heel, mid summer in a shaded frame. Forms roots by the end of September but should be overwintered in a frame[].
Cuttings of almost ripe wood, 5 - 10cm with a heel, September in a cold frame. Forms roots in the following summer. Plant out in autumn or spring[].