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.

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.

The castor bean is important for its oil which is used as a lubricant, biodiesel ingredient, and rodent repellent, among other applications. The plants are now commercially planted globally, with India producing nearly 75% of the world's castor oil. Castor beans cannot be eaten because they contain a potent poison that's released if the seed is broken.

Matted Sandmat is an annual weed that grows flat along the ground into a matted form. It has a long tap root and hardy seeds, which make it difficult to eradicate. This plant’s sap can irritate the skin and is toxic.

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.

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.

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.

Argemone mexicana has been naturalized in many parts of the world. It is extremely tolerant of drought and poor soil, but is poisonous to grazing animals. Its seed pods secrete a pale yellow latex when cut open. In India, the mexican prickly poppy is used in the Holika Dahan festival, in which adults and children worship by offering flowers.

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.

Apple of Sodom, or Calotropis procera, is an extremely poisonous plant. The fruit of this plant ripens and bursts, causing the seeds to scatter. In Jamaica, the fibers inside of the fruit are collected and used to stuff pillows.

Lady of the night (Brunfelsia uniflora) is an evergreen tropical tree that will grow from 2.5 to 7 m tall. It blooms in spring with highly-fragrant, yellowish-white flowers. Perfume is made from the oil of the flowers. Blossoms attract butterflies and moths. Native to the Amazon, it prefers partial shade and moist, well-drained, slightly acidic soil.

Jatropha gossypiifolia, commonly known as bellyache bush, black physicnut or cotton-leaf physicnut, is a species of flowering plant in the spurge family, Euphorbiaceae. The species is native to Mexico, South America, Gujarat State (India) and the Caribbean islands. It is a declared noxious weed in Puerto Rico and is naturalised in northern Australia, including Queensland where it is listed as a Class 2 declared pest plant. It grows to 2.5 to 4 m high. The three lobed leaves are purple and sticky when young and become bright green with age. The small red flowers with yellow centres appear in clusters. These are followed by cherry-sized seed pods that are poisonous. Powdery mildew fungal disease was reported. There are many common names for Jatropha gossypiifolia including: bellyache-bush, black physicnut, and cotton-leaf physicnut in English; pinon negro, pinon colorado, and tua-tua in Spanish; medicinier noir and medicinier rouge in French; mamoninha and peao-roxo in Brazil; jarak merah and sibidigua in India.

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.

Slender false garlic (Nothoscordum gracile) is a herbaceous perennial that will grow to 51 cm tall. It blooms from spring to summer with clusters of small white flowers with purple stripes and colorful green and gold stamens. Flowers bloom at the top of the stem. Considered a weed it is commonly found growing along sandy roadsides and woods. Attracts bees and other pollinators.

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.

Cape gooseberry (Physalis peruviana) is a perennial shrub species native to South America. This species has been cultivated by humans for a very long time, and can be traced to the Incan civilization. Cape gooseberry grows optimally in fertile, slightly acidic soil in full sun.

Asthma-plant (Euphorbia hirta) is a ground-hugging spurge weed whose branches can grow to 61 cm long. It blooms from summer through early fall, dying off after the first frost. A milky sap will seep from broken stems or leaves. It can be a nuisance weed that reproduces rapidly.

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.

Spineless butcher's-broom (Ruscus hypophyllum) is an evergreen shrub that is native to the Mediterranian region. It expands through a creeping root system, allowing it to become a widespread groundcover plant in just a few growing seasons. The flowers are unremarkable and will only on rare occasions fully mature into small red berries.

Spanish broom is a deciduous shrub native to the Mediterranean, West Asia, and North Africa. Fragrant yellow pea-like flowers cover the shoots in late spring and summer. It is cultivated for its ornamental value and is used for flavoring and essential oil extraction.