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.

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.

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.

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.

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.

Bird of paradise is generally considered non-toxic but can be poisonous when ingested in large quantities. Cases of poisoning are typically mild to moderate with symptoms including abdominal cramps, nausea, vomiting, and diarrhea. Cases of poisoning may be more serious in children. The fruit and seeds are considered to be the most toxic parts of the plant. The frequent use of this plant as a houseplant could be a factor in poisoning frequency. This plant can be mistaken for another more toxic species, Poinciana gilliesii, as they share the same common name, bird of paradise.

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.

All parts of the evergreen spindle are considered toxic if ingested in large quantities. Symptoms can range from mild to life-threatening including vomiting, weakness, diarrhea, chills, convulsions, and coma. Since these plants are commonly used as ornamental hedges, you should be mindful of any children who may encounter the plant, be attracted by its colorful leaves and flowers, and may be tempted to eat them.

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.

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.

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.

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.

Although its berries look juicy and tempting, the fruits and the root of pokeweed are toxic and should not be eaten. Pokeweed is considered a pest species by farmers but is nevertheless often grown as an ornamental plant. Its berries can be made into pokeberry ink as well.

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.

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.

Wild daffodils have low-level toxicity when the leaves or bulbs are ingested. The bulbs, however, are the most toxic part of the plant. If the bulbs are ingested, symptoms may include vomiting, diarrhea, and excessive salivation. If a large quantity is consumed, convulsions, low blood pressure, tremors, and cardiac arrhythmias may occur. Poisoning is most likely to occur from accidental ingestion by children, as wild daffodils are grown in gardens around the world.

Oleander is moderately to highly toxic to humans – instances of ingestion, or physical contact with this plant's sap, should be immediately addressed by medical professionals. While fatal cases of oleander poisoning are very rare, they are possible. All parts of this plant are toxic if ingested. Physical contact with the plant's sap, which is found throughout the plant and is more likely to be exposed if the plant is cut or damaged, may cause dermatological symptoms, including redness and itchiness of the skin. Symptoms following ingestion include low blood pressure, lethargy, an irregular heartbeat, blurred vision, confusion, diarrhea, vomiting, dizziness, fainting and, in extreme cases, death. Be mindful of curious children, as oleanders are an extremely common ornamental plant cultivated in gardens and parks around the world.

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.

Old man's beard (Clematis vitalba) is a deciduous climbing shrub that will grow to 12 m tall. It blooms with fluffy flowers and fruits that have long silky strands that look like the wispy beard of an old man. This plant is a food source for a variety of moths. Often seen scrambling over hedgerows, it is considered a noxious weed, especially in New Zealand. Evidence suggests ancient Europeans made rope and baskets with old man's beard.

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.