Poisonous Outdoor Plants - Trees and Shrubs

Subscribe to our free E-Newsletter, "Agri-News" (formerly RTW This Week)Agri-News
This Week
Malus spp.

Description: small, round-headed deciduous trees grown for their large fruit: apples. The simple leaves often have fine downy hairs, and the margins are toothed. The bark of young shoots is usually downy.

Poisonous Part: Foliage, seeds.

Symptoms: Abdominal pains, nausea, vomiting, death. (Internal poisoning: cyanogenetic glycosides)
Celastrus scandens

Description: A coarse-looking, woody, deciduous climbing vine sometimes encountered in cultivation. The leaves are about 10 cm long, alternate and oval. The greenish, yellowish or white flowers are borne in clusters and later develop orange-yellow fruit capsules with crimson seeds.

Poisonous Part: Leaves, seeds, roots.

Symptoms: Vomiting, diarrhea, chills, weakness, convulsions, coma. (Internal poisoning: unknown)
Rhamnus spp.

Description: Deciduous shrubs, found in Alberta. R. alnifolia is a native shrub found in low shaded woods. Common buckthorn (R. cathartica) and the glossy buckthorn (R. frangula) are grown as ornamentals. The latter have been reported to adversely affect humans when large quantities of the fruit are eaten. The simple leaves may be dull or shiny green and have obvious parallel veins. The flowers are greenish yellow or white. The small fruits have a stone in the centre and turn black when ripe. R. cathartica is spiny.

Poisonous Part: Fruit, bark.

Symptoms: Muscle spasms, stomach upset and laxative effects. (Internal poisoning: glycosides)
Burning Bush
Euonymus spp.

Description: Species and cultivars of this genus grown as ornamental bushes, vines and groundcovers. E. atropurpureus and E. europaeus are frequently cited as poisonous plants; however, they are not hardy in Alberta. Treat other Euonymus species that are hardy and grown in Alberta with caution. The stems are usually four-sided and may be winged. The simple leaves often have many fine teeth and may be very narrow. The flowers are small and greenish. The seeds have a pink-scarlet fleshy cover.

Poisonous Part: Leaves, bark, fruit.

Symptoms: Vomiting, diarrhea, convulsions, hallucination. (Internal poisoning: unknown)
Caragana arborescens

Description: A common ornamental shrub or small tree used as specimen plants or in hedges. The fernleaf and weeping caraganas are named cultivars of C. arborescens. Caraganas are legumes and have 6 - 12 rounded leaflets/leaf. Yellow flowers bloom in spring. Seeds are enclosed in 4 - 5 cm long pods.

Poisonous Part: Seeds.

Symptoms: Vomiting, diarrhea, (Internal poisoning: unknown)
Clematis, Virgin’s Bower
Clematis spp.

Description: A woody climber grown for its showy flowers and feathery fruit. Leaves have 3 - 7 leaflets, and the edges are often serrated. It usually kills back each winter, but can grow 2 m a season under good conditions. There is also a native clematis, rarely seen in cultivation. Ornamental types usually have purple-rose coloured flowers.

Poisonous Part: All parts.

Symptoms: Stomach upset, nervous condition, depression, death. (Internal poisoning: protoanemonin)
Daphne spp.

Description: A group of small woody shrubs, the largest not over 1.1 m and the smallest not over 30 cm in height. Several daphnes are found in cultivation in Alberta. Daphne flowers are small and showy and can be either lilac, pink or yellow. They grow in stalkless groups of three, bloom before the leaves come out and are 1 cm or less long. Leaves are thin, ovalish and 5 - 8 cm long, Highly toxic. Greatest danger lies in the attractive appearance of the berries to children. The one-seeded, round fruit is about 0.5 cm in diameter, leathery and scarlet-coloured.

Poisonous Part: All parts.

Symptoms: Blisters on skin, burning of mouth, throat and stomach, stupor, weakness, convulsions, vomiting, diarrhea, coma, death. (Internal poisoning: dihydroxycoumarin-type glycosides)
Sambucus spp.

Description: Shrubs with either loose, open or compact habits of growth, 1.3 m to 2.6 m tall. Branches of all species are stout and pithy, and flowers are small, white and borne in clusters at the ends of branches. The fruit, growing in clusters, may be blue, purple or red and have a small pit.

Poisonous Part: All parts, roots and especially berries; harmless when cooked.

Symptoms: Nausea, vomiting, diarrhea. (Internal poisoning: alkaloids and glycosides)
Hydrangea spp.

Description: Medium-sized, coarse-textured, deciduous ornamental shrubs. Leaves 7 - 15 cm long, shiny green above and lighter green below. The large clusters of white flowers grow in June or July. The pot hydrangea sold by florists is also poisonous.

Poisonous Part: All parts.

Symptoms: Abdominal pains, nausea, vomiting, death. (Internal poisoning: cyanogenetic glycosides)
Juniperus spp.

Description: Low spreading evergreen shrubs growing wild or planted as ornamentals. Has needle-like leaves, often bluish green. The berries are purple-blue with a waxy bloom.

Poisonous Part: Berries

Symptoms: Digestive upset. (Internal poisoning: unknown)
Quercus spp.

Description: Deciduous trees with a long oval silhouette, horizontal branches, mature height about 10 m. Leaves are dark green and deeply-lobed. The fruit is the common acorn. The only oak commonly grown in Alberta is bur oak (Q. macrocarpa). The bur oak has very rough bark, and the stiff leaves turn muddy brown in autumn.

Poisonous Part: Leaves, unleached acorns.

Symptoms: Symptoms in humans not recorded but has been known to cause death in animals. A large number of acorns would have to be eaten to cause harm. (Internal poisoning: possibly annic acid)
Ohio Buckeye, Horsechestnut
Aesculus glabra

Description: A small (approx 8 m), round-headed tree. Has large compound leaves with 5 - 7 leaflets arranged like the fingers on a hand, each about 10 - 15 cm long and hairless on both sides. The flowers are greenish-yellow and are produced in upright clusters. The large fruit is a spiny capsule, enclosing 1 - 2 shiny brown seeds. The closely related horsechestnut
(A. hippocastanum) is also potentially harmful. However, the horsechestnut is not usually found in the northern part of Alberta and occurs only rarely in southern Alberta.

Poisonous Part: All parts, especially mature fruit.

Symptoms: Vomiting, diarrhea, weakness, lack of body control, stupor, dilated pupils, paralysis, death. (internal poisoning: aesculin)
Virgina Creeper
Parthenocissus quinquefolia

Description: A hardy, deciduous, ornamental climber belonging to the grape family. Leaves are large, coarse and compound with up to five 15 cm long leaflets. The leaves are dull green on top and paler below. The fruit is a small blue berry borne in grape-like clusters.

Poisonous Part: Berries, leaves.

Symptoms: Evidence for poisoning by this plant is circumstantial in that it is believed, but not proven, that ingestion has caused death of children. It should be regarded with suspicion. (Internal poisoning: unknown)
Wild Cherries
Prunus spp.

Description: Numerous members of the cherry family grow in Alberta; however, the poisonous ones to note are pincherry (P. pensylvanica), chokecherry (P. virginiana) and the purple-leaved Shubert chokecherry (P. virginiana cv. Shubert). The pincherry and chokecherry grow wild or can be in cultivation whereas the Shubert chokecherry is only found in cultivation. The trees are small (pincherry to 6 m, chokecherry to 3 m) have smooth, shiny, dark brown bark and produce stalks of white flowers in June. Seeds of the closely related peach and apricot plants are also poisonous.

Poisonous Part: All parts, fruit safe if pits removed.

Symptoms: Abdominal pains, nausea, vomiting, coma, sweating, lethargy. Can cause laboured breathing, death and muscle spasms in cattle and horses. (Internal poisoning: cyanogenetic glycosides)
Taxus spp.

Description: In Alberta, dwarf coniferous plants with attractive dark green, often glossy foliage. The fruit is berry-like, about 1 cm in diameter and coral to deep pink. Not often grown as an ornamental but sometimes found in evergreen woods. Highly toxic.

Poisonous Part: All parts, the fleshy red covering around the seed is not especially toxic.

Symptoms: Vomiting and diarrhea, trembling, difficulty in breathing, weakness, convulsions, coma. Can cause poisoning in livestock. (Internal poisoning: the alkaloid taxine)

Other Documents in the Series

  Poisonous Outdoor Plants - Introduction
Poisonous Outdoor Plants - Garden Plants: Vegetables
Poisonous Outdoor Plants - Garden Plants: Flowers
Poisonous Outdoor Plants - Trees and Shrubs - Current Document
Poisonous Outdoor Plants - Field Plants
Poisonous Outdoor Plants - Forest Plants
Poisonous Outdoor Plants - Marsh Plants
Poisonous Outdoor Plants - References
Share via AddThis.com
For more information about the content of this document, contact Robert Spencer.
This document is maintained by Jennifer Rutter.
This information published to the web on November 22, 2010.