All parts of common columbine, including the stem, leaves, flowers, and seeds, are toxic when they are ingested raw. Contact with the plant's sap may also lead to dermatitis (skin irritation and inflammation). The symptoms from common columbine poisoning are likely to cause only mild to moderate effects, but the symptoms are not well-known, since there are few documented cases of it. Adverse effects are most likely to occur from accidental ingestion.

Indian poke (Phytolacca acinosa) is a perennial shrub with deep red or purple berries. The genus name for this species comes from a Greek word for “plant” and a Latin word that means “dye,” and a look at the berries makes the reason obvious. Its mature leaves and stalks are poisonous.

Creeping buttercup can be severely toxic to dogs; you should seek immediate veterinary attention if you believe your dog has eaten or come into contact with a plant of this type. All parts of these plants contain ranunculin, a toxin that is poisonous when swallowed and also can irritate skin, causing redness or itch. Ingestion symptoms ranging from excessive drooling, vomiting, diarrhea, weakness, and loss of appetite to paralysis, seizures, jaundice, spasms, collapse, or even death.

Common barberry is a shrub with unpleasant-smelling flowers and red berries. The flowers can be used to create yellow dye while the berries have culinary and medicinal uses in Iran and medicinal use in China that dates back 3,000 years. Despite this, common barberry can be a host to wheat rust that is highly damaging to grain crops in America.

True to this plant's reputation, consumption of potato can be extremely toxic to dogs, and warrants immediate veterinary attention. All parts of these plants contain several toxic substances which can cause loss of appetite, excessive drooling, vomiting, diarrhea, dilated pupils, confusion, behavioral changes, and weakness. In more severe cases, difficulty breathing, a lowered heart rate, coma, or even death may occur, so treat it as a medical emergency if your pet has come into contact with this plant.

Hairy willowherb (Epilobium hirsutum) is a species of weed that is difficult to eradicate. It is not known to be toxic, but the sale of this plant or its seeds has been banned in some areas. This is because its dense, aggressive growth habits can crowd out and destroy other native beneficial plants.

Cow parsnip (Heracleum sphondylium) is a species of flowering perennial herb related to parsley and fennel. Its specific epithet, "sphondylium," means "vertebrate," and references its segmented appearance. This species produces extremely large amounts of nectar and thus attracts many bees.

Smoketree is a deciduous tree native to Southern Europe and Central China. The flowers of the smoketree are pinkish-purple and long-lasting. They grow in clusters along branches and give a smoky appearance to the tree when in bloom. In China, they are used as important fall decorations due to their foliage turn bright red in the fall.

Autumn crocus (Colchicum autumnale) is a flowering plant native to the coast of the Mediterranean and the Black Sea. Its flower stalks grow up after a period of time after its leaves die out, so you can see its flowers or leaves but never both. Consumption of autumn crocus is toxic and is particularly poisonous to cats. Autumn crocus is not the source of saffron. Saffron is produced by another species in the crocus family.

The Daphne mezereum is a deciduous shrub that can grow up to 1.5 m tall. Its leaves are soft, spirally arranged on the stems. The february daphne produces a bright red berry as the fruit which is extremely poisonous for humans.

If either ingested or touched, dieffenbachia can cause negative reactions. The symptoms range from moderate to severe and can be dangerous if airways are blocked. Due to the calcium oxalate contained in this plant, its leaves and sap have toxic properties. When ingested, they can induce symptoms such as lip and tongue swelling, drooling, speech loss, and difficulty breathing; when touched, they can cause a painful skin rash or eye irritation. Since these plants are often found indoors as decorative plants, be careful when keeping them around small children. Always wear gloves when handling this plant.

Striped barbados lily is perennial herbs with showy flowers but it contains toxic compounds, most notably alkaloids lycorine and tazetine, as well as calcium oxalate crystals.

Hyacinthus orientalis is one of the heralds of spring. The name common hyacinth comes from the Greek name Hyacinthus. According to Greek legend, Hyacinthus was admired by both Apollo and Zephyrus. Hyacinthus ended up being killed out of jealousy and a flower bloomed on the spot where his blood was spilled. Apollo named the flower after his lost love.

Grape Leaf Begonia can easily be cultivated and has decorative flowers. These flowers are the main reason why people cultivate this plant. It has succulent stems which enables it to store water for drought. It is distinct for having glossy features and symmetrical leaves.

Evergreen azalea are members of the Rhododendron genus, all of which contain varying levels of a toxin known as Grayanotoxin in all tissues. Physical contact can cause a rash in sensitive people, the pollen can irritate mucus membranes, and ingesting it can cause nausea, vomiting, arrhythmia, low blood pressure, and hallucinations in humans. Grayanotoxin is so strong that even the amounts contained in honey made from Rhododendron pollen can have negative effects.

Mexican lily (Hippeastrum reginae) is a plant species native to Venezuela, Bolivia, Peru and Brazil. Historically, mexican lily has been valued for its blossoms and has been the subject of still life paintings. This species was discovered by famous naturalist Carl Linnaeus in 1759.

Common yew is highly toxic to all animal species, including humans, dogs, cats, livestock and poultry, with all parts of the plant capable of causing death when consumed in large amounts.

Blackthorn (Prunus spinosa) is a large deciduous shrub species that is also commonly called a sloe. Blackthorn is indigenous to Europe, Asia, and Africa. In Britain, this species is used to make a liquor called sloe gin. In Ireland, its wood is made into walking sticks.

Durian (Durio zibethinus) is a tropical plant from Southeast Asia. It bears large, spiny, edible fruit which has become a major export crop of the region. The fruit is best known for its pungent smell, which provokes opposing reactions, ranging from near-addiction to revulsion. In some areas, it has even been banned from public transport and hotels.

Common mistletoe (Viscum album) is a shrub that grows on the stems of trees. Its native range is in Europe, but it has been imported to North America as well. Common mistletoe is parasitic, getting most of its water and nutrients from the host tree. All portions of the plant are toxic and can be fatal if ingested in concentrated form.