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.

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.

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.

Cuckoo pint (Arum maculatum) is a perennial that will grow to 51 cm tall. It blooms in spring with male and female flowers that spring be yellow or purple. Male flowers have tiny hairs to trap insects that are attracted by the scent of the blossoms. This entrapment covers the insect in pollen before it can escape to pollinate other flowers. Female flowers give way to bright red berries in summer that are highly poisonous.

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.

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.

Greater creeping spearwort 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.

Celery-leaved 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.

Giant hogweed (Heracleum mantegazzianum) is a very large, 2 to 5 m tall, herbaceous, flowering perennial with many amusing names - Giant Cow Parsley, Hogsbane, and even Giant Alien. However, names are the only thing funny about this plant - it is a phototoxic invasive species. In combination with light, its sap causes phytophotodermatitis, a serious skin inflammation with blistering and scarring which can last for up to several days.

Sun spurge (Euphorbia helioscopia) is a winter annual that grows along the ground in a variety of locations from gardens to wastelands. It features distinctive red colored stems with toothed leaves that emit a toxic milky sap when cut or torn. Pale yellow flowers bloom from spring to summer and give way to fruit. This plant is considered a weed.

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.

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.

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.

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.

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.

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.

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.

Pontic rhododendron (Rhododendron ponticum) is a dense shrub species that is one of the most extensively cultivated Rhododendron species in western Europe. Pontic rhododendron is native to southern Europe and southwest Asia. This species is widely cultivated for ornamental purposes, and considered invasive in western Europe. Honey produced from the pollen of this species is poisonous.

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.