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.

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.

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.

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.

Bearded iris is known to cause contact dermatitis in some individuals. The most commonly reported symptom is minor skin irritation, typically lasting only a few minutes. This can result from contact with the seeds, roots, or sap of this plant. Furthermore, all parts of bearded iris are toxic when ingested, especially the roots. Symptoms typically including minor or moderate burning sensations, nausea, vomiting, abdominal pain, diarrhea, and fever. This plant is most often encountered in a garden context, where it is planted as an ornamental.

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.

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.

Woodland horsetail (Equisetum sylvaticum) is a perennial plant species native to North America and Eurasia. Woodland horsetail grows in swampy forest, open woodlands, and meadow areas. This species is considered one of the most attractive species of horsetail.

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.

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.

Henbane is a poisonous annual or biennial plant that is native to the Mediterranean. The plant is entirely covered with greasy hairs. Its seeds spread from mid-spring to early fall.

Rough horsetail (Equisetum hyemale) is an evergreen perennial. An aggressive grower, it reproduces through spores and is non-flowering. It prefers full sun to partial shade and is pest resistant. It provides erosion control, grows well in wetlands and makes an interesting addition to water gardens. Expected height of 61 to 91 cm.

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.

Amazon Lily (Eucharis amazonica) is a perennial native to Peru which has also been naturalized in Venezuela, Mexico, and many tropical islands. It grows as much as 75 cm in height, with large waxy leaves and fragrant flowers. The name amazon Lily is often also used for the Eucharis genus in general, which can cause some confusion.

Devil's-backbone (Euphorbia tithymaloides) is a succulent species of spurge native to North and Central America. It has been planted in gardens since the 17th century and valued for its unique appearance and its habit of attracting hummingbirds. However, nearly all parts of this species are toxic and should not be consumed.

All parts of the persian cyclamen contain toxins that are extremely hazardous to dogs, with the highest concentration in their tubers. Use caution if your dog is in a yard where persian cyclamen is found, especially if they enjoy digging. Symptoms range from lethargy to coma, and immediate veterinary care is needed to pump the canine's stomach to void the body of the toxin.

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.