Medicinal Tree Fact Sheets
We will be adding more information about individual trees and shrubs on this page.
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Viburnum opulus L.
Common name: Cramp Bark, Guelder Rose, Snowball tree
Description: A deciduous small tree, with showy white flowers and translucent red berries, having stem bark which has anti-spasmodic properties.
Habitat: Cramp bark is found in hedgerows, woodlands, fens and scrubland throughout most of Europe and north and west Asia. It thrives in moist soils and will grow in both moderately acid and alkaline soils.
History: Cramp bark may have longstanding use, although few records show this. It was mentioned by Chaucer, and John Gerard described the use of Rose Elder or Gelders Rose in his herbal of 1597. The Guelder Rose form originally from Holland with large round white heads of flowers is mainly seen as an ornamental shrub in gardens. The native form has flatter flowerheads and attractive but intensely bitter tasting red berries. An American variety Viburnum opulus var. americanum, is the Highbush or American Cranberry.
Planting: Cramp bark needs no special treatment if planted in a moist location with plenty of light at the woodland edge. The shrub will survive in shade although it is more productive of flowers and fruits in lighter conditions. It is hardy to zone 3 and is not frost tender.
Cultivation: Regenerates quickly after cutting and is a good candidate for coppice production so a close spacing of plants can reflect this form of cultivation. Cuttings of half-ripe wood can be used to grow additional plants.
Harvest: For medicinal use, the bark can be harvested in the spring, when it will peel away easily from stems several years old and can be used fresh or dry to make a tincture preserved with up to 25-30% alcohol. The bark can also be dried and then powdered for capsules. Dosage of dried bark powder is from 6-12 g per day, dosage of 1:5 tincture from 5-10 ml per day.
Constituents: The bark contains resin, viburnin (bitter glycoside), valeric and isovalerianic acids, salicin, tannins, iridoid glycosides (penstemide, patrinoside and others), coumarins (scopoletin, aesculetin), triterpenes (oleanolic and ursolic acids).
Research: Actions are antispasmodic, astringent, mild sedative, hypotensive, peripheral vasodilator. Constituents such as coumarins have spasmolytic activity and Cramp bark is helpful in conditions where pain arises from muscular tension: such as cramps, menstrual pain, muscle spasm, some kinds of constipation, irritable bowel syndrome. There has been limited clinical research relating to Viburnum opulus. One study found that constituents of Viburnum opulus had antispasmodic effects on smooth muscle (Nicholson, 1972), and Cometa et al. (2009) found that alcohol-soluble constituents of the related North American tree Viburnum prunifolium, such as iridoid glucosides, contributed to muscle relaxant properties.
Contra-indications: For the stem bark of Viburnum opulus there are no reported harmful effects in pregnancy or breastfeeding. However, general advice in pregnancy is to seek professional opinion before taking any medications, and advice should also be taken about use of Cramp bark alongside medications to lower blood pressure.
Ginkgo biloba L.
Common name: Maidenhair tree
Description: A deciduous tree growing up to 30 m tall and 9 m wide, with fan-shaped leaves. The ginkgo is regarded as a living fossil, related to tree ferns and cycads. Trees may be male or female, although this may not be determined until the tree is old enough (35 years) to produce seed. Many cultivars exist, particularly for the striking golden yellow leaves in autumn.
Habitat: The ginkgo is a native of China, growing in silty soils along stream banks, but is endangered in the wild. It is widely grown in Europe and America. It can grow in a wide range of soils, and can tolerate drought and pollution, though preferring well-watered and well-drained soil. The ginkgo is a hardy tree and does not need frost protection.
History: Ginkgo has longstanding use in traditional Chinese medicine, and is a widely sold supplement throughout the world.
Planting: Ginkgo can be grown on, in a container, using good quality multi-purpose compost with 10% grit added. Keep moist but ensure that the pot drains freely. Water well when in leaf as rain will tend to be shed away from the pot by the leaves. For potted plants a little slow-release fertiliser can be added to the surface of the soil in spring, plants in the ground do not need additional fertiliser.
Cultivation: Ginkgo is a slow growing tree, averaging less than 30 cm per year. The young trees are slender with few branches, and have few pests or diseases. It can be readily coppiced or pruned, best done while dormant in January or February.
Harvest: For medicinal use leaves are harvested in the late summer, just as they start to turn yellow, and can be dried for later use. Female trees eventually produce edible fruit containing butanoic acid which smells like rancid butter.
Constituents: The leaves contain flavonoids and terpenoids which have anti-oxidant effects in the body.
Research: Many trials have been carried out with standardised extracts containing around 24% flavone glycosides and 6% terpene lactones. Some studies have found evidence of improvements in circulation to the eye and brain and decreases in intermittent claudication (poor circulation in legs). Studies have considered possible benefits in dementia, memory and tinnitus.
Contra-indications: Can increase bleeding and so caution is needed in using ginkgo alongside blood thinners or anti-coagulant medication. Discontinue taking ginkgo at least two weeks before if you are having dental or surgical treatment.
Zanthoxylum americanum Mill.
Common name: Northern prickly ash, Toothache tree
Description: A deciduous shrub of the Rue family with pinnately compound leaves and thorny branches growing up to 4 m tall and 4 m wide. Inconspicuous flowers are produced May-June and the small black berry-like seeds ripen September-October. A close relative is the Hercules club or Southern prickly ash (Zanthoxylum clava-herculis) and oriental varieties are the Szechuan pepper (Zanthoxylum simulans) and Japanese pepper tree (Zanthoxylum piperitum). In Nigeria the root of Zanthoxylum zanthoxyloides is used as a chewing stick.
Habitat: The Northern Prickly Ash is native to central and eastern North America. It does not need frost protection, being hardy to UK zone 4. As an understorey shrub in damp woods in the wild, it can grow in partial shade. It is ideal for a woodland edge and will grow in most soils.
History: Members of the Zanthoxylum species group can be found in tropical as well as temperate climates, and often have traditional culinary and medicinal uses because of the aromatic spicy foliage, bark and seeds. The edible seeds can be used instead of pepper. The description of ‘Toothache tree’ probably arises from the numbing and tingling sensation experienced when chewing a leaf or seed. Prickly ash has been used for its circulatory stimulant properties in cramps and rheumatism.
Planting: Prickly ash should be planted in well-drained soil that does not dry out. For berry production, some advisers say that both male and female plants are needed while others say this is not necessary.
Cultivation: Prickly ash can produce suckers to form a thicket if left unpruned, and its growth habit is somewhat like a large gooseberry bush. It can be readily thinned or pruned to a single-stemmed small tree, or shaped in an open goblet style like a gooseberry bush, and this pruning is best done while dormant in winter. Take care to wear thick gloves when pruning as the stems have sharp thorns. Cuttings of half-ripe wood can be used to grow additional plants.
Harvest: For medicinal use, fresh young leaves and twigs can be harvested in the spring and used to make a tincture preserved with 25-30% alcohol. The bark and roots can also be used in this way. The bark and berries can also be dried and then powdered.
Constituents: The plant contains iso-quinoline-type alkaloids, amides, coumarins, resins, tannins and volatile oil.
Research: Some research studies have been carried out, showing anti-inflammatory, anti-fungal, anti-viral and anti-bacterial effects of various parts of the plant and the distilled essential oil. More recent studies suggest that Zanthoxylum species may have a role to play in anti-cancer drug development.
Contra-indications: The use of Zanthoxylum species is generally accepted in small amounts in food as a condiment. The safety of use in pregnancy has not been established, and it should be avoided due to the alkaloid content.
Hamamelis virginiana L.
Common name: Virginian Witch Hazel
Description: A deciduous shrub or tree with alternate leaves and arching branches growing up to 6 m tall. Spidery yellow fragrant flowers are produced in late autumn. Seed capsules are produced which stay on the branch until the following year and then burst open to project the small shiny black seeds over 3 m.
Habitat: The witch hazel is a native of the eastern half of North America. It is a hardy tree and does not need frost protection. As an understorey tree in damp woods in the wild, it can readily grow in partial shade. It prefers a rich moist soil which is on the acidic side.
History: Witch hazel extracts were first brought to wider attention in the nineteenth century, when settlers identified potential uses from the North American Indians. It is now widely used in eye drops, skin creams, toners, and cosmetics. The Virginian witch hazel is also the basis for grafts of Asian cultivars with larger flowers.
Planting: Witch hazel can be readily grown on, in a container, using good quality multi-purpose compost. Keep moist but ensure that the pot drains freely. Water well when in leaf as rain will tend to be shed away from the pot by the leaves. For potted plants, a little slow-release fertiliser can be added to the surface of the soil in spring, while plants in the ground do not need additional fertiliser.
Cultivation: Witch hazel has a branching habit. It can be readily thinned or pruned, and this is best done while dormant in January or February. As a large shrub, witch hazel provides attractive autumn colour with small but unusual late autumn flowers.
Harvest: For medicinal use, fresh young leaves and twigs are harvested in the spring and a distilled extract is preserved with up to 15% alcohol. The bark is also used to make a distillate and in North America, whole trees are used to make the distillate in large manufacturing operations.
Constituents: The plant contains tannins, phenolic acids, flavonoids and other constituents which are astringent and anti-inflammatory.
Research: Few research studies have been carried out, although witch hazel extracts are considered effective in traditional use against inflammation. The distilled extract has longstanding use for calming skin conditions ranging from insect bites to acne, eczema and haemorrhoids.
Contra-indications: Witch hazel extracts are regarded as safe and well-tolerated on the skin, but not for internal use due to the tannin content.