In China, the pistachio is known as the 'happy nut' due to the open smile of its shell. It was first cultivated 100,000 years ago in Iran and Syria from where it spread to Greece and the rest of Europe. Legend has it that lovers used to meet in the pistachio groves to listen for the crack of the nuts opening as a sign of good fortune.

The open shell of the pistachio enables it to be roasted and salted while still in its shell, and that's how they're most often eaten. They're also found in many Middle Eastern and Mediterranean pastries.

Pistachios are a good source of calcium, magnesium, phosphorous, potassium, iron, folate and protein.
The pecan is a native to North America where they were an important food source for the native Indian tribes of the southern USA. Pecans are still used in abundance in America, especially in cakes, breads and cookies.
Hazelnuts (or cobnuts - a type of wild hazelnut) were collected and eaten by Mesolithic people but most of our cultivated varieties originated in the last century. Although hazels grow in most parts of Britain, cobnuts are particular to Kent where they're grown on a commercial scale. Most of the world's commercially grown hazelnuts come from Turkey.

The nuts are globe-shaped or oval, up to 2cm (1in) long with a hard brown shell. They tend to grow in clusters of one to four nuts, partially enclosed in a husk. High in fibre, potassium, calcium, magnesium and vitamin E, hazelnuts are nutritious as well as tasty.

They're used in savoury dishes, such as nut roast, and in many cakes, biscuits and puddings, as well as being a key ingredient in praline chocolate.
For many, the taste of coconut instantly conjures up images of lazy days on a tropical beach and swimming in the warm sea. The coconut grows on a classic palm tree, often on the shoreline, and has many uses. The nut has a hard shell that grows inside a hairy husk. The inside of the nut is filled with coconut juice, which is delicious when drunk fresh. As the nut ripens this juice is gradually absorbed to make the coconut flesh.

Coconut can be used in a number of ways, both in savoury and sweet dishes. Coconut milk is made from squeezing the flesh in water and used often in spicy tropical dishes. Coconut and its milk are both high in protein, fats and carbohydrates.