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.

The heart of jesus plant has a name that implies purity, but it is actually toxic. Like other Caladiums, its sap is extremely irritating when eaten or even just applied to the skin. A painful, itchy rash breaks out on contact. That rash is essentially what a person who ingests it will experience as well, except inside of their mouths and all the way down their digestive tracts. Besides a great deal of pain and irritation, this causes severe nausea, excessive salivation, vomiting and diarrhea, and also significant swelling in many cases. Keep this plant away from children.

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.

True to this plant's reputation, consumption of turkey berry 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.

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.

Golden dewdrops (Duranta erecta) is an ornamental sprawling shrub commonly found in subtropical and tropical gardens all over the world. Its gentle purple blossoms are often visited by butterflies and hummingbirds. Golden dewdrops is considered a weed in Australia, South Africa and certain parts of East Asia.

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.

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.

This evergreen tree is the main source of world-famous spices nutmeg and mace. Nutmeg is actually the seed of several species of the genus Myristica, while the spice mace is derived from the reddish seed covering. The history related to nutmeg and mace is quite tragic. They were rare and precious spices at one time, and bloody wars were waged over their control.

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.

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.

Another name for scarlet begonia (Begonia coccinea) is angel wing begonia because its oval-shaped leaves remind some people of angel wings. Others think it looks like the wings of a mythical flying beast: begonia dragon wing is an alternative name for it. The plants are native to South America, where they love to clamber up the sides of cliffs.

Plants of the Asclepias curassavica genus are extremely toxic to dogs—immediate veterinary attention should be sought if your dog has consumed anything of this type. Toxins are found in all parts of the plant. Symptoms of poisoning from bloodflower include weakness, dilated pupils, vomiting, and diarrhea. In more serious cases, these symptoms may progress towards difficulty breathing, an elevated heart rate, organ failure, coma, or death.

Squirrel Corn gets its common name from the small, yellow tubers growing from its roots that have the appearance of corn. This flowering plant is native to North America and features unique, heart-shaped flowers. Squirrel Corn, or Dicentra canadensis, blooms in spring and goes dormant for the summer.

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.

Often grown as a houseplant, Ficus triangularis' foliage sets it apart: The leaves are shaped like triangles, which is why the plant is sometimes called the "triangle ficus." Milky-white sap from the plant's leaves is considered toxic, as it can cause skin irritation in humans.

American elder (Sambucus canadensis) is a North American native deciduous shrub with enormous inflorescence of grouped small white flowers and dangling bunches of mauveine berries. When cooked, the fruits can be added to pies, pancakes, and jellies. Wine can also be produced from its flowers and fruits. The bushy leaves and arching branches attract wildlife, providing nesting space for birds.

The crown Flower has beautiful flowers that are used to make leis and were a favorite of the last queen of Hawaii. The outer petals of this flower curl back, and reveal what looks like a crown inside. The sap of this plant may cause skin irritation and can be considered toxic.

Many species within the Cycas revoluta genus are highly toxic to dogs - if you suspect your dog has ingested any part of a sago palm plant, you should contact a vet immediately. The Sago palm is a very common ornamental and is the most common culprit. These plants contain high concentrations of the cycasin toxin, which is found throughout their structures but is most concentrated in their seeds. Ingesting even a small amount of cycasin can cause vomiting and diarrhea. Larger amounts can cause damage to the intestines and liver, coma, or death.

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.