The berries of the Japanese honeysuckle, or Lonicera japonica, are considered poisonous for human consumption, although the nectar of the flowers can be safely extracted and eaten. In the wild, birds and foraging animals make it a regular part of their diet, and the American Society for the Prevention of Cruelty to Animals does not consider the plant toxic to cats, dogs or horses.
Also known as woodbine and Chinese honeysuckle, Japanese honeysuckle is native to Asia but found in nearly every U.S. state. An evergreen, climbing or trailing vine that is considered weedy, Japanese honeysuckle is distinguished by black, glossy berries and white-, pink- or yellow-coloured fragrant, tubular flowers with five-parted petals. Leaves are light green-coloured, simple and opposite, while the vine's wood is white and soft, and will grow between 15 and 30 feet in length, usually spreading over forest ground, fences and climbing other trees.
The vines of Japanese honeysuckle contain saponic and cyanogenic glycosides, while the black berries contain carotenoids. The nectar of the flower is the only safe part of the plant to eat. If the berries are ingested in large numbers the reaction can be fatal, but otherwise symptoms include vomiting, diarrhoea, cold sweat, dilated pupils and rapid heartbeat. In some cases, respiratory failure, convulsions and even coma may occur.
Japanese honeysuckle is safe for foraging animals and birds, which are not harmed by the ingestion of the plant's leaves and berries. The U.S. Forest Service recognises Japanese honeysuckle for its help in maintaining the white-tailed deer in the southern and eastern United States, and many cottontail rabbits, cattle, sheep, and goats safely partake, as well. The berries of the Japanese honeysuckle are enjoyed by fruit birds, wild turkeys and northern bobwhites. The ASPCA does not consider Japanese honeysuckle to be a threat to cats, dogs or horses.
If you accidentally ingest the berries of the Japanese honeysuckle vine, contact a poison control centre hotline or emergency medical centre immediately.