Capsicum species

There are perhaps fifty thousand Capsicum cultivars grown worldwide. The USDA-ARS GRIN seed collection contains 6,200 Capsicum accessions alone, which include 4000 Capsicum annuum accessions. The other Capsicum species in the USDA germplasm repository include C. chinense, C. baccatum, C. frutescens, C. pubescens, C. cardenasii, C. chacoense, C. flexuosum, C. eximium, C. rhomboideum, C. galapagoense, and C. tovarii.

There are five major species of cultivated Capsicum, C. annuum, C. chinense, C. baccatum, C. frutescens, C. pubescens, and within those species are several "taxonomic varieties".

Because of the ability of many of species to cross and generate inter-specific hybrids, albeit with low success, there are also, what is referred to as "complexes" within the Capsicum genus of closely related and sexually compatible species. This includes the Capsicum annuum complex, which consists of C. annuum, C. frutescens, and C. chinense.

Major species and their taxonomic varieties

Capsicum annuum, which includes bell peppers, sweet/Italian peppers, serrano, cayenne, paprika and jalapeños

Capsicum baccatum, which includes the South American varieties, such as ají amarillo, ají limon and criolla sella

Capsicum chinense, which includes all of the Habaneros, Scotch Bonnets, Trinidad Scorpions, the Bhut Jolokia and the Carolina Reaper.

Capsicum pubescens, which includes the Rocoto and Manzano pepper, and are distinctive plants in having violet flowers, black seeds and hairy dark green leaves and grows as a large multi-stemmed vine up to 5 meters long.

Capsicum frutescens, which includes the Brazilian Malagueta, the Tabascos and many of the peppers grown in India.

Sometimes C. frutescens is not distinguished as a species separate from C. annuum, while other botanists consider it and C. annuum to be conspecific.

Types of cultivars

The species and varieties include many economically important cultivars with different shapes, colors, and flavors that are grown for different purposes, such as spices, vegetables, and herbal medicines.

Some confusion has resulted from the legal term "plant variety", which is used interchangeably with "cultivar" (not with "taxonomic variety"). The terminology around a cultivar also includes terms such as heirloom, open-pollinated, self-pollinated, and hybrid.

Heirloom varieties are typically those that have been selected and grown historically with seed saved every year, and are still maintained today in similar fashion, such as the blocky-type California Wonder.

Open-pollinated varieties are those that are maintained without strict barriers to prevent out-crossing and then seed is collected at and stored from each harvest such as the lamuyo-type Marconi Yellow.

While open-pollinated varieties are typically true-to-type, there may be occasional out-crossing to other

Capsicum varieties that may introduce some heterogeneity. Self-pollinated varieties are similar to open-pollinated varieties in that they are true-to-type and seed is collected at and stored from each harvest, but measures are taken to minimize out-crossing.

This may involve placing a barrier such as a mesh bag or cage over the plant to prevent pollinators from reaching flowers, ensuring that the plant has "selfed". This is how much seed intended for home-garden use is produce, like the cultivar Early Jalapeño.

These three types of cultivar seed production are all similar in that only one parent is used and the seed are produced generally through selfing.

Hybrid varieties take advantage of a phenomena called heterosis or hybrid vigor, which occurs in pepper. To generate a hybrid variety, two self-pollinated varieties are intentionally crossed, and all seed from this cross are collected.

The new hybrid variety typically is more vigorous than either of the two parents contributing to traits such as higher yield. Hybrid seed if saved will not produce a homogeneous set of plants the next generation, meaning that the two parents will need to be crossed again to generate more hybrid seed.

This method is used to produce hybrid Capsicum cultivars such as the blocky-types Double-Up and Orange Blaze. Much of the commercial pepper production uses hybrid varieties for their improved traits.

Due to the large and changing number of cultivars, and the variation of cultivar naming in different regions, this list only gives a few examples of the estimated 50,000 pepper varieties that exist.