Chilli pepper plants appear in our garden from our home-made compost in late winter-early spring and are continuing to germinate till now, so we enjoy a range of species from the excitably-hot to the meekly-mild types and an extended season well into the summer.

The chilli pepper, or simply "chilli", is the fruit of species of the New World genus Capsicum from the nightshade family Solanaceae.

This large, tropical family includes tomatoes and potatoes. It is anticipated that new species are yet to be discovered and named, as exploration of the New World develops.

Their natural domicile, together with their cultivars, is the Americas. They are now cultivated worldwide, for they have become a global culinary phenomenon as well as possessing important medicinal virtues.

"Chilli" was the original Romanisation of the Aztec word for the fruit. The term chilli generally applies to the smaller, hot types of capsicum. The mild, larger forms are called "bell pepper".

In the Americas, chillies have formed part of the human diet since 7,500BC.

Archaeological evidence at sites located in south-western Ecuador reveal that they were already well domesticated more than 6,000 years ago and were one of the first cultivated crops in the Americas.

Christopher Columbus was one of the first Europeans to discover them (in the Caribbean) and named them "peppers" due to their similarity in pungency with the Old World peppers of the "Piper genus", although they are dissimilar in appearance.

From Mexico chillies quickly spread into the Philippines and then to India, China, Korea and Japan with the assistance of European sailors. The new spice readily formed a vital ingredient in the local cuisines.

Lizzie Collingham, in her book Curry, suggests that the distribution of chilli took an alternative route.

She maintains that the Portuguese transported chilli from Spain to India and cites her evidence that the chilli pepper features heavily in the Goan region of India, which was the site of a Portuguese colony.

She also cites the journey of chilli from India, through Central Asia and Turkey to Hungary, where it became the national spice in the form of paprika.

The most common species of chillies are: Capsicum annum, which embraces many common varieties such as bell peppers, paprika, jalape–os and the chiltepin; Capsicum frutescens, whose renowned cultivars are in the Tabasco Group; Capsicum pubescens, which embraces the South American rocoto peppers with distinctive purple seeds; Capsicum baccatum, commonly called aji in South America and Capsicum chinense, selections of which embraces the world's hottest chillies such as naga, habanero and Scotch bonnet.

The pungency or heat in chillies when ingested or applied topically, is produced by a group of chemicals collectively called capsaicinoids.

Even a minute concentration of these will produce a burning sensation in any tissue they meet, particularly moist, mucous membranes such as those lining the mouth, throat, nose and eyes.

Their intensity rests primarily with the species or cultivar, while their levels are also predisposed by growing conditions and the age of the fruit.

The "heat" of chillies is measured in Scoville Heat Units (SHU) named in honour of the American chemist Wilbur Scoville (1865-1942). Bell peppers grade at 0 (SHU), New Mexico green chillies at around 1,500 (SHU) and Jalape–os at 3,000-6,000 (SHU).

The present record holders for the hottest chillies include selections of C chinense from Bangladesh and the northeast Indian States.

These comprise the British-cultivated Dorset Naga, selected from the Bangladeshi cultivar Naga Morrich; Nagahari, researched by scientists working in Assam and Bhut Jolokia produced from Assamese seed researchers at New Mexico State University. Reported heat levels varied from 855,000 to over 1,000,000 SHU and are accordingly, the hottest chillies ever researched.

To reduce the heat of a pod, remove the seeds and the inner membranes.

In India, the chilli is used, besides in the phenomenal array of culinary dishes, to ward off evil spirits. It is also used to detect the evil eye and remove its effects.

Hot chillies are rich in vitamin C and are believed to have many beneficial health effects. The pain triggered by capsicum stimulates the brain to produce endorphins, natural opioids, which act as analgesics and produce a feeling of well-being. In addition, they are an excellent source of most B vitamins, especially B6.

They are high in potassium, magnesium and iron.

Recent studies reveal that hot chillies can have a wide range of benefits from serving to alleviate pain in arthritic patients, to acting effectively against cancer-causing tumours.

Hot chillies, together with other species are also known for facilitating the death of parasites in the gastro-intestinal tract.

There-fore, they are a practical dietary component in tropical regions.

Chillies also have cardiovascular benefits, weight-loss properties (by inducing thermo-genesis) and lower the risk of diabetes.

The amount of insulin required to lower blood sugar after a meal is reduced if the meal contains chillies.

There are chilli species and cultivars to suit every palate and ensure healthy living. They also look wonderful in floral arrangements and are magical when used to decorate a Christmas tree.