Common Foxglove

The common foxglove is grown for decorative and medicinal purposes. The flowers contain glycosides, chemicals that can be used to regulate and improve heartbeat. If plant materials containing glycosides are directly eaten by human beings, nausea, abdominal pain, diarrhoea, and heartbeat and pulse abnormalities can result. If large enough quantities are consumed, convulsions and death can ensue.

Deni Bown/Oxford Scientific Films

Oleander

The oleander, a bushy evergreen shrub native to southern Europe, is also widely planted in warm regions as a decorative shrub.

Dorling Kindersley

Potato Plant

Native to the Andes of Peru, the potato plant is now cultivated throughout the temperate regions of the world. It is grown for human consumption and for its starch, which is used in the manufacture of alcohol and adhesives.

G.I. Bernard/Oxford Scientific Films

Bracken Fiddleheads

The "fiddleheads" on a bracken plant are the young, unrolling fronds. Bracken, or brake, is a common fern found in many parts of the world. It produces two poisonous chemicals that destroy thiamine (vitamin B1) and cause widespread haemorrhaging and bone marrow destruction.

Ronald Toms/Oxford Scientific Films

Poison Hemlock

The name "poison hemlock" refers to two entirely different poisonous herbs (Conium, pictured here, and Cicuta) that, if eaten, can cause convulsions, respiratory arrest, damage to the central nervous system, and death. Native to Europe and the United States, these plants range in size from 5 cm to 3 m (2 in to 10 ft).

G.A. Maclean/Oxford Scientific Films

Fruit of The Castor-Oil Plant

The spiny fruit of Ricinus communis, which is also known as the castor-oil plant, contains the beans from which the traditional purgative, castor oil, is pressed. With further processing, castor beans yield a type of oil suited for use in paints, varnishes, and dyes. In their natural state, however, the seeds, along with all other parts of the plant, are highly poisonous.

Nigel Cattlin/Holt Studios/Animals Animals

Meadow Buttercup

Although buttercups such as Ranunculus acris, pictured here, abound in pastures, grazing cows avoid them; ingesting the foliage irritates the mucous membranes of the digestive tract. However, dried buttercups are harmless inclusions in hay.

Dorling Kindersley

Star-of-Bethlehem

The star-of-Bethlehem is widely cultivated for its white, star-shaped flowers. The herb contains poisons in its bulb that can cause death if eaten.

Marshall Black/Oxford Scientific Films

Yew

The yew tree is cultivated as an ornamental plant. The bark of the Pacific yew has certain chemical derivatives that show promise in the treatment of ovarian cancer.

Dorling Kindersley

Spindle

Spindle or woody nightshade (Solanum dulcamara) is a climbing plant that belongs to the Solanaceae family. It is commonly found in damp areas on the edges of woods and in hedges in Europe. The typical Solanaceae flower consists of five folded-back petals from which the yellow, stunted conical stamens project.

Richard Shiell/Animals Animals

Nightshade

All parts of the deadly nightshade, or belladonna, Atropa belladonna, are poisonous. The drug atropine, used to dilate the pupils of the eyes, is one of several narcotics extracted from its leaves and roots.

Dorling Kindersley