It is thought there were about 3-4 species of wild hot chile peppers, genus Capsicum. Humans hybridized and selected them into the chiles available now. It is usually difficult to tell where the species and varieties originated, since they have been valued by cooks for millennia, and seeds have been traded over long distances. Their descendants have differing cultivation requirements, based on their ancestry. Almost all chiles have white flowers, and tan seeds.
Chile peppers, Capsicum species, are native to the Americas. They were carried all over the world by the Portuguese and Spanish. The hot cuisines of southeast Asia could not incorporate chiles until after European contact.
Chile peppers are woody shrubs in habitat, not annuals, though they are often treated as annuals in cultivation. If grown in pots, they can be maintaned for many years. They are very susceptible to spider mites if wintered indoors under lights, or in a window with wan sunlight.
One species was from the Caribbean basin lowlands, and grew in full sun. Modern descendants include the Habañero and Scotch Bonnet peppers. These are extremely hot peppers. They have smallish, rectangular, wrinkled, and vertically compressed fruits. They resemble small lanterns. They ripen to yellow, orange or red. Fruits hang downwards, with the blossom end pointing at the ground. This kind of plant likes a hot, humid climate year round. Its seeds are hard to sprout in temperatures cooler than about 80-85 F / 27-30C. This pepper does not perform well in hot, dry climates such as mine, nor in cool-night climates. I would think these would be difficult to grow, even in a greenhouse, in northern Europe or the US, unless night heat were provided. A magnificent appetizer is prepared from Habañero peppers in Guadalajara, Jalisco, México: Slice Habañeros into extremely fine slices. Toast small, 3"-4" / 7.5-10cm diameter corn tortillas over a fire until browning, but still soft enough to roll. This also works directly on an electric burner, turning constantly with the hands. While tortillas are still hot, place a few Habañero threads onto the tortilla, roll, and serve with fine tequila.
Another chile species, resembling the modern Rocoto pepper, grew in full sun high in the Andes. These have black seeds, in contrast to the tan seeds all other Capsicum have. These are very to extremely hot peppers. Fruits tend to be red when ripe, claw-shaped, and the blossom end points downwards when ripe. These are cool-growing peppers that don't tolerate hot weather. They do well in coastal southern California, and I suspect they would do well outdoors through much of northern Europe. They are not common in cultivation in the US because they aren't fond of summer temperatures in most of the country. I have a brother who can grow them superbly in Laguna Niguel, a coastal community in southern California. He has been offered $10 a pound for these peppers by co-workers.
Capsicum glabriusculum grows wild from southern Arizona into northern México. It is known as chiltepin or chile tepin. This is one of the hottest peppers in existence. A single dried fruit, the size of a pea, will provide substantial heat to an entire cooking pot with 20 quarts / liters of chile, or marinara sauce. The woody, shrubby plants grow in riverine gallery forests, under mesquite and similar trees. Leaves are very much smaller than other peppers. Fruits are small, as mentioned above. There may only be 4-5 seeds per fruit. Fruits in different regions may be spherical, or may be slightly conical. They point upwards when ripe, and mature to bright red. Plants are stiffly upright, and very narrow, in habit. They can be fruited easily in a 1 gallon / 4 liter standard nursery container. This chile also requires very hot temperatures to sprout. If you can keep the seeds warm enough to sprout them, this makes a beautiful container plant that is seldom wider than its pot. There are cultivars with purple foliage and flowers.
A fourth species grew in mid-elevation highlands, in full sun, perhaps in México or Central America. This pepper has large leaves. This kind of pepper prefers warm to hot days, and cooler nights. Most peppers grown and used in México are descended from this species. They can be very hot, all the way to completely heat-free. Most non-hot bell peppers are also of this type. This kind of pepper tends to be rectangular in cross-section, and has fruits that hang down when ripe. Famous descendants include peppers grown around Hatch, New Mexico, USA, and the mid-level Mexican highlands. Pueblo cultures in the US, in Arizona and New Mexico, grew these peppers. These peppers are difficult to grow well in areas with warm to hot summer nights, like I have. They are also difficult to grow in areas with cool days. This kind of pepper does well as a summer annual in most temperate climates in the USA and Europe.
This is a great source for heirloom varieties of peppers:
Native Seeds/SEARCH - Home
Many have been collected from ancient pueblos here in the US, and Native American settlements in México.
NSS has redone their Web site since I last visited. The chiles are here:
Seeds > Chiles/Peppers | Native Seeds/SEARCH
and the chiltepines are here:
Seeds > Chiltepines (Wild Chiles) | Native Seeds/SEARCH