Although botanically unrelated, white bryony and black bryony are very similar in appearance and share the same climbing habit and large underground tuber. Rapid growth can swamp plants they grow up so control is often necessary.
Latin name Bryonia dioica (white bryony), Tamus communis (black bryony)
Areas affected shrubs beds, hedges, beneath trees and along walls
Main causes weed with climbing habit and tuberous rootstock
Timing treat in summer or early autumn
What is bryony?
Both white bryony (Bryonia dioica) and black bryony (Tamus communis) are strong climbers that can grow 3m (10ft) or more in a season. The weight of the stems can break down smaller shrubs and smother growth.
The flowers of both types of bryony are pollinated by bees. Flowers can occur from late spring through to late summer and can attract many different species of bees.
This page looks at options for gardeners when either type of bryony is becoming a problem.
White bryony (Bryonia dioica), is a scrambling climber in the cucumber family, Cucurbitaceae, developing several stems and producing greenish flowers in the summer followed by red fruits in the autumn. All parts, including the acrid-tasting red berries, are poisonous. May also cause skin irritation so wear gloves when handling.
Black bryony (Tamus communis) is a member of the yam family, Dioscoreaceae, and is a twining climber. Insignificant spikes of small, yellow-green flowers are produced in early summer (May to July) and the conspicuous strings of red berries often remain on the dead stems throughout autumn. The berries are not edible.
To distinguish between the two, white bryony has five-lobed leaves, larger flowers and tendrils, whereas black bryony has heart-shaped leaves, tiny flowers and no tendrils.
Both types of bryony form a tuberous rootstock, initially small, but increasing over several years to form a very large tuber weighing, in the case of white bryony, perhaps several kilos.
Bryony is often found growing in inaccessible situations among tree roots or in hedgerows, from seeds that have been dropped by birds. It may also grow under, or close to, large shrubs where birds perch, or along walls or fence sides.
The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.
For seedlings: A watch should be kept out as, in the first growing season, their tuberous roots can usually be lifted out easily with a hand trowel.
For mature plants: The best approach is to dig out the tuberous root where the situation permits, tracing back the stems to the crown of the tuber which may be 7.5-10cm (3-4in) below soil level. Even if only some of the tuber is removed, this may be sufficient to prevent further regrowth. However, given the tendency for bryony to appear in tight spaces, digging out may not be an option.
An alternative method is to lay the long, trailing, leafy stems, still attached to the rootstock, on a hard surface, such as a path or bare earth (not grass), then spray with the non-selective herbicide glyphosate (e.g. Roundup Fast Action, SBM Job done General Purpose Weedkiller or Doff Advanced Concentrated Weedkiller). This should succeed in checking it, but there may be regrowth the following season. This weedkiller is best applied between July and mid-September rather than in early spring.
As glyphosate is not selective in its action, it is essential to avoid spray or spray drift coming into contact with garden plants. If treating weeds in the immediate vicinity of garden plants, apply carefully using a ready-to-use spray in cool, calm weather. Branches or shoots can be held back, using canes, or by covering or screening while spraying, but make sure that the weed foliage has dried before releasing branches or removing the covering.
Inclusion of a weedkiller product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.
Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see section 4)
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.