Poisonous Outdoor Plants - Garden Plants: Flowers

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Autumn Crocus
Colchicum autumnale

Description: This crocus-like, bulbous plant is commonly grown for its showy purple flowers, appearing without leaves in the fall. Often advertised for indoor forcing. Has 3 - 8 leaves, 20 - 25 cm long and 3 cm wide.

Poisonous Part: All parts, especially bulbs.

Symptoms: Irregular heartbeat, confusion, burning sensation, nausea, diarrhea, weakness, death. Can cause poisoning in livestock. (Internal poisoning: colchicine)
Black Nightshade
Solanum nigrum

Description: A weedy annual with clusters of small white flowers and green berries turning black or yellow when ripe. Related to the tomato. The leaves may be hairy. Included in the flower garden section because the plant is more toxic to humans than those contained in the field plants section. Highly toxic.

Poisonous Part: All parts, including immature fruit; ripe berries are edible.

Symptoms: Nausea, vomiting, abdominal pains, constipation, or bloody diarrhea, sluggishness, salivation, labored breathing, trembling, weakness, loss of feeling, paralysis, death. Can cause poisoning in livestock. Symptoms include laboured breathing, convulsions, pupil dilation and death. (Internal poisoning: solanine)
Bleeding Heart
Dicentra spp.

Description: Both the common Bleeding Heart (D. spectabilis) and the Pacific or Western Bleeding Heart (D. Formosa) are commonly grown perennials in Alberta (about 1 m and 30 cm tall, respectively). They are often used in shade where they will bloom profusely. Foliage is finely divided and has a ‘bloom’ on both surfaces. Flowers are heart-shaped, rose to pink with white centres; they appear in spring and hang from a long, arching, leafless main stem.

Poisonous Part: All parts.

Symptoms: Trembling, loss of balance, weakness, difficulty in breathing, convulsions. (Internal poisoning: isoguinoline – structured alkaloids)
Bracken Fern, Brake
Pteridium aquilinum

Description: A coarse fern, up to 1.5 m tall. Dark brown, branched rhizomes (horizontal roots). The stiff fronds (leaves) are somewhat fan-shaped and the mid-rib is often hairy. Found in wooded, mountain areas.

Poisonous Part: All parts green or dry. The rhizome is most poisonous.

Symptoms: Sometimes mistakenly eaten as fiddleheads. Poisoning unlikely though because the enzyme is destroyed by heat. Causes a thiamine deficiency. Has been known to cause sickness and loss of cattle in Canada. (Internal poisoning: enzyme thiaminase)
Castor Bean
Ricinus communis

Description: As a foliage plant, this annual can grow taller that 2 m. The 5 - 11 lobed leaves may be 1 m across and vary from green to bronze depending on the cultivar. Stems have watery juice. Spiny seed pods grow in clusters, enclosing glossy mottled black, brown and white seeds. Poisoning can be prevented by removing the flower heads before they completely form.
Highly toxic.

Poisonous Part: Seeds, foliage, young seedlings.

Symptoms: Handling leaves and seeds may cause itching rash to broken blisters, chewing plant parts causes burning in mouth, throat and stomach, loss of appetite, abdominal pain, vomiting, dullness, diarrhea, thirst, convulsion, death. Can cause poisoning in cattle. (Dermatitis and internal poisoning: ricin)
Coneflower, Black-eyed Susan
Rudbeckia spp.

Description: This group of plants includes a number of herbaceous ornamentals. Poisoning of livestock has been reported for the golden-glow coneflower (R. laciniata cv. florepleno) and the gloriosa daisy (R. hirta).

R. hirta also grows wild in Alberta and is often known as the common black-eyed Susan. The golden glow coneflower is a 1.5 m spreading plant with attractive double yellow flowers in August and September. The common black-eyed Susan produces flowers 5 cm across in shades of yellow and maroon.

Poisonous Part: All parts.

Symptoms: Poisoning in humans not reported, only in cattle and horses. Large amounts need be ingested to cause harm. (Potential internal poisoning)
Daffodil, Narcissus
Narcissus spp.

Description: Daffodils are bulbous plants widely cultivated for their white, yellow and combined yellow and white flowers that appear in early spring. There are one or more flowers on a long, hollow stalk. Leaves are green, flat and strap-shaped.

Poisonous Part: All parts, especially bulbs.

Symptoms: Nausea, severe stomach and intestinal upset, vomiting, diarrhea, trembling, stupor, itchiness, convulsions, death. Can cause poisoning in cattle with symptoms including convulsions, drowsiness and gastroenteritis.(Internal poisoning: alkaloids)
Delphinium, Larkspur
Delphinium spp.

Description: A group of about 250 annual or perennial plants from
0.6 - 2 m tall that produce spikes of white, blue, purple and pink flowers. Each flower has a spur that projects backwards. Foliage is lightish green and finely divided in a finger-like fashion. Not all species are equally toxic.

Poisonous Part: All parts, young plants and seeds especially.

Symptoms: Nausea, abdominal cramps, bloating, twitching muscles, paralysis, death. Has been known to cause poisoning in cattle with symptoms including constipation, paralysis, weakness and salivation. (Internal poisoning, dermatitis: diterpenoid alkaloids)
Flowering Tobacco
Nicotiana alata

Description: Herbaceous annuals valued for their rapid growth, large leaves and showy flowers. All species of Nicotiana are poisonous; however, N. alata is the most commonly cultivated garden tobacco. Stem and leaves are sticky and hairy. Flowers are fragrant, tubular and come in many colours.

Poisonous Part: All parts.

Symptoms: Twitching muscles, rapid heartbeat, staggering, weakness, blindness, nausea, vomiting, diarrhea, abdominal pains, death. (Internal poisoning: nicotine)
Digitalis purpurea

Description: A tall-growing (up to 1.5 m) biennial that produces tall spikes of trumpet-shaped flowers of various colours often spotted inside. Leaves are spaced alternately on the stem, are hairy and remain green throughout the winter. One of the original sources of the drug digitalis.

Poisonous Part: All parts.

Symptoms: Nausea, diarrhea, abdominal pain, headache, confusion, blurred vision, trembling, drowsiness, irregular heartbeat, convulsions, death. Can cause poisoning in cattle. (Internal poisoning: cardiac glycosides)
Gas Plant
Dictamnus albus

Description: An uncommon garden perennial growing 60 cm to 1 m tall. Leaves are glossy and strong smelling; leaflets are about 7.5 cm long, with
9 - 11 leaflets per leaf. Has spikes of white or pink flowers.

Poisonous Part: All parts, especially seed pods and plant juices.

Symptoms: Irregular reddish patches on the skin, blistering and staining of the skin, which may persist for several weeks. (Dermatitis)

Solidago spp.

Description: This group of plants contains several species commonly grown in the garden (S. canadensis and S. missouriensis) and several native species. They can be 1 - 1.5 m tall and produce many small heads of deep yellow flowers on tall stalks in late summer to early fall. Leaves are long and narrow, may have toothed margins.

Poisonous Part: All parts.

Symptoms: Poisoning of humans not reported; however, losses of horses, cattle and sheep have been noted. (Internal poisoning: resinous compounds)
Hyacinthus orientalis

Description: A perennial, spring flowering bulb with long, narrow leaves. The flowers, in a cluster on a stalk, may be white, yellow, pink, red or blue. Sometimes sold as an indoor flowering bulb.

Poisonous Part: All parts can cause sickness; the bulb is most toxic.

Symptoms: Intense stomach cramps, nausea, vomiting, diarrhea. (Internal poisoning: alkaloids. Dematitis in sensitive people)
Iris spp.

Description: This common garden plant can grow anywhere from 30 cm to 1.5 m tall depending on the species. Flower colours: white, pink, orange, brown, yellow, blue and violet. The leaves are long, erect, sword-like and are produced from thick, fleshy horizontal rootstocks.

Poisonous Part: Leaves, rhizomes, plant juices.

Symptoms: Nausea, vomiting, diarrhea. Has been known to cause abdominal pain, blistering, diarrhea, death and mouth irritation in cattle. (Internal poisoning: irisin)
Convallaria majalis

Description: A common garden perennial or ground cover grown for its attractive green foliage and sweet-scented, white, nodding, cup-shaded flowers in spring. Spreading habit of growth by underground rootstocks. The leaves are broad, oval and shiny and are produced in pairs. The flowering stems arise between the leaves.

Poisonous Part: All parts.

Symptoms: Irregular heartbeat, nausea, confusion, pupil dilation, headache, circulatory collapse, death. (Internal poisoning: convallarin, convallamarin)
Lobelia spp.

Description: Numerous poisonings by species of lobelia have been reported where the plants have been used in medicinal preparations. The flowers can be pink, white or blue. An annual bedding plant, mound forming or trailing; L. erinus is most common. Usually less than 20 cm tall, the narrow leaves are 1 - 2.5 cm long.

Poisonous Part: All parts.

Symptoms: Vomiting, weakness, tumors, coma. (Internal poisoning: a-lobeline)
Lupinus spp.

Description: Lupines grow wild, and both annuals and perennials are cultivated in gardens where they grow to approximately 60 cm to 1 m in height. Pea-like flowers are produced in spikes and may be blue, pink, red, yellow or apricot and may be bicoloured. Each leaf consists of many leaflets arranged like fingers on a hand. Some, but not all lupines are toxic.

Poisonous Part: all parts, especially seeds.

Symptoms: Ingestion of a relatively large quantity of lupines over a brief time is generally required. Symptoms include difficulty breathing, twitching, convulsions, unconsciousness, death. Has been known to cause poisoning and death in cattle, sheep, goats and horses. (Internal poisoning: alkaloids)
Aconitum spp.

Description: A showy perennial that grows to about 1.5 m high and flowers in late summer and early fall. Tall, showy upright spikes of helmet-shaped flowers are produced in tones of blue, violet and purple. Has tuber-like roots. The leaves are glossy, dark green and are arranged like fingers on a hand, resembling the foliage of its close relative the delphinium or larkspur.

A. napellus is the common garden plant, and A. delphinium is a native perennial found in the Rocky Mountains, Coalspur, Jasper and northwards.

Poisonous Part: All parts, especially roots and seeds.

Symptoms: Restlessness, salivation, weakness, heartbeat irregularity, nausea, dizziness, anxiety, speech and vision impairment, death if sufficient quantities ingested. (Internal poisoning: alkaloids)
Morning Glory
Ipomoea spp.

Description: Vining, herbaceous, annual plant. Leaves are heart-shaped. Tubular flowers may be single or multi-coloured, usually white, blue or red. Four to six seeds in a capsule.

Poisonous Part: Seeds

Symptoms: Hallucinogenic reactions when 50 or more seeds are eaten. Nausea, digestive upset, blurred vision, mental confusion, low blood pressure, coma. (Internal poisoning: amides of lysergic acid)
Pheasant's Eye
Adonis spp.

Description: Several species of this genus are sometimes cultivated in gardens: spring adonis (A. vernalis) and Amur adonis (A. amuriensis). Both plants are about 45 cm tall. The fern-like leaves are 8 - 15 cm wide and long. The flowers, one per stem, are produced in early spring.

Poisonous Part: All parts.

Symptoms: Poisoning of humans has not been reported; however, losses of livestock have been noted. (Internal poisoning: adonidon)
Papaver spp.

Description: The Iceland poppy (P. nudicaule) and the oriental poppy (P. orientale) are commonly grown in Alberta. The latter is not known to be poisonous; however, all poppies should be treated as potentially harmful unless proven otherwise. Several poppies also grow wild. Tissue-thin poppy flowers are about 10 cm across in white, orange, red, deep pink and yellow.
P. nudicaule has deeply cut leaves, and the stem is very hairy. P. orientale has entire leaves, and the stem is smooth. Both produce a milky sap. It is illegal to grow the opium poppy (P. somniferum) in this country because opium and its derivatives – heroin and morphine – are gathered from the juice of raw seeds.

Poisonous Part: All parts, especially raw, green seeds; ripe poppy seeds are harmless.

Symptoms: Eating unripe fruit – deep sleep, dizziness, delirium, slow breathing, death. Poisoning and addiction from opium and its derivatives are common. Eating other parts – nausea, vomiting, stomach pains, twitching muscles. Has been known to cause bloat, muscle spasms and restlessness in livestock. (Internal poisoning: alkaloids)
Sneezeweed, Bitterweed
Helenium autumnale

Description: Grown as a cultivated flower (not popular) and exists as a wildflower. It is a coarse, 0.6 to 1.2 m tall, late-blooming member of the daisy family. The stems usually branch near the top of the plant. Flowers of the native plants are yellow; introduced cultivars can have yellow, red or yellow and maroon flowers. The alternate, nearly smooth leaves are usually lance-shaped, but some are as thin as grass.

Poisonous Part: All parts.

Symptoms: Symptoms in humans not reported; however, poisoning noted in livestock with symptoms including laboured breathing, convulsions and frothing of the mouth in cattle. (Internal poisoning: dugaldin)
Squill, Scilla
Scilla spp.

Description: Early spring flowering bulbs about 15 cm tall, producing small blue, nodding blooms. The two scillas known to be toxic are not hardy in Alberta; however, it is wise to consider the scillas S. sibirica, Siberian squill, and S. bifolia, two-leafed squill, as potentially harmful. A closely related plant Urginea maritima, sea onion, is used in making rat poison.

Poisonous Part: All parts, especially the bulb.

Symptoms: Nausea, diarrhea, abdominal pain, headache, confusion, blurred vision, trembling, drowsiness, irregular heartbeat, convulsions, death. (Internal poisoning: cardiac glycosides)
Star-of-Bethlehem, Snow Drop
Ornithogalum umbellatum

Description: A spring-flowering bulb that produces long, narrow (15 x 0.8 cm) bright green leaves. White, star-shaped flowers grow in clusters of 5 - 20.

Poisonous Part: All parts.

Symptoms: Depression, salivation, vomiting, diarrhea, labored breathing, rapid pulse, bloody urine, death. (Internal poisoning: cardiac glycosides)
Sweet Pea, Perennial Pea
Lathyrus odoratus, L. latifolius

Description: Both plants are tall growing vines (2 m) that produce a multitude of flowers in clusters of usually 3 - 5 along their stems. The stems are angular and winged. The sweet pea (L. odoratus), grown as an annual in Alberta, has fragrant flowers in many colours. Seeds are borne in hairy pods. The perennial pea (L. latifolius) is perennial if grown in a protected location. The flowers are rose or white, and the pods are 8 - 12 cm long.

Poisonous Part: Seeds.

Symptoms: Ingestion of large amounts is necessary to induce the following symptoms; prickly sensation, cramps, lameness, paralysis, death. (Internal poisoning: beta-gamma-L-glutamyl-aminopropionitrile in sweet pea and L-alpha, gamma-diaminobutyric acid in perennial pea)
Tanacetum vulgare

Description: A common roadside weed easily recognized by its strong aromatic scent when handled and by its flat-topped clusters of hard button-shaped yellow flowers. The fern-like foliage is almost hairless and has small dots or pits. At one time, grown as a savory herb. A large quantity of leaves would have to be eaten to cause poisoning; however, death has been noted after ingesting a “medicinal” extract prepared from the plant.

Poisonous Part: All parts.

Symptoms: Convulsions, violent spasms, dilated pupils, rapid and feeble pulse, death. (Internal poisoning: tanacetin)
Wild Tomato
Solanum triflorum

Description: A common, low-spreading annual weed related to the tomato. The leaves have deep, rounded lobes and are slightly hairy. White flowers are in groups of 1 - 3. The fruits resemble small (2.5 cm) green tomatoes.

Poisonous Part: Leaves, berries.

Symptoms: Nausea, vomiting, abdominal pains, diarrhea, sluggishness, salivation, labored breathing, trembling, loss of feeling, paralysis, death. (Internal poisoning: solanaceous alkaloids)


Other Documents in the Series

  Poisonous Outdoor Plants - Introduction
Poisonous Outdoor Plants - Garden Plants: Vegetables
Poisonous Outdoor Plants - Garden Plants: Flowers - Current Document
Poisonous Outdoor Plants - Trees and Shrubs
Poisonous Outdoor Plants - Field Plants
Poisonous Outdoor Plants - Forest Plants
Poisonous Outdoor Plants - Marsh Plants
Poisonous Outdoor Plants - References
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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.