Whether you’re biting into a sweet and juicy bell pepper or turning up the heat with a fiery habanero, you’re no stranger to the plant genus Capsicum. Capsicum has been cultivated and consumed for thousands of years, and every chili and sweet pepper at your market belongs to it.
Botanists now count 43 species in the genus. Most are wild plants you won’t find in a store, and five were domesticated. Those five are behind every pepper you cook with, so they’re where you’ll want to start.
What is the genus Capsicum?
What most people today refer to as “peppers” are all part of the plant genus Capsicum. Black pepper is the exception, the dried fruit of a vine from another family, and our what is a chili pepper explainer covers how the two ended up sharing a name.
But what’s the difference between a pepper and a chili pepper? Is a chilli something other than a chile, and different again from a chili? Our chili vs. chile guide sorts out the spellings. Spelling aside, Capsicum by any other name is still just that: Capsicum.
Capsicum belongs to the nightshade family, Solanaceae, the same family as tomatoes, eggplants and potatoes. Its closest relative is a genus called Lycianthes, and a PhytoKeys monograph covering every Capsicum species, published in 2022, treats the two as the only members of their tribe. In the wild, Capsicum grows from the southern United States to central Argentina and Brazil.
You’ll find the name is older than modern botany. Joseph Pitton de Tournefort used Capsicum in his Institutiones, and Linnaeus kept it when he formally named the genus in 1753. Where the word comes from is less certain, and our genus vs. species explainer goes through the two usual explanations.
How many species of Capsicum are there?
Forty-three, according to that 2022 monograph, the most recent full treatment of the genus. The count includes Capsicum mirum, a species its authors described for the first time.
Seen “26 wild species and 5 domesticated” quoted somewhere, including on an older version of this page? That figure is out of date. A 2006 paper put the genus at 20 to 30 species, and in 2015 the USDA’s germplasm database recognized 38. The total climbs as botanists find and describe new ones, so treat any count as a snapshot.
Five of the 43 were domesticated: annuum, chinense, baccatum, frutescens and pubescens. So what are the rest? Wild plants, and they’re a varied bunch. Capsicum galapagoense grows only on the Galápagos Islands. And several Andean species, Capsicum rhomboideum among them, make fruit with zero heat.
Some domesticated species have wild forms of their own, too. The chiltepin, a pea-sized pepper also called the bird pepper, is wild Capsicum annuum. The monograph calls it the most widely distributed member of the genus, growing from the southern United States to northern Bolivia.
Below the species level, the numbers stop being countable. Cross-pollination, both in nature and through deliberate breeding, keeps producing new varieties, and Kew says annuum alone comes in several thousand kinds, with nobody sure exactly how many.
What are the five domesticated Capsicum species?
Here are the five side by side, with where each was domesticated and the heat range our pepper list holds for each:
| Species | Peppers you’ll know | Domesticated in | Heat range in our list (SHU) |
|---|---|---|---|
| annuum | Jalapeño, poblano, bell pepper, cayenne | Mexico | 0 to 100,000 |
| chinense | Habanero, scotch bonnet, ghost pepper, Carolina Reaper | The Amazon basin | 0 to 3,000,000 |
| baccatum | Aji amarillo, lemon drop, bishop’s crown | Bolivia or Peru | 500 to 50,000 |
| frutescens | Tabasco, malagueta, peri-peri | Uncertain | 30,000 to 350,000 |
| pubescens | Rocoto, manzano | Bolivia | 12,000 to 100,000 |
Capsicum annuum
Capsicum annuum is the most common of the five, as well as the most extensively cultivated. Peppers of this species include a wide range of flavors and intensities from sweet to mild to hot.
Many favorites are members of this species, including the cayenne, the jalapeño and the New Mexican chiles, such as the Anaheim and Hatch. It’s also the only species on our list with heatless peppers, and the bell pepper is the best known of them.
Capsicum chinense
If you’re a spice junkie who loves to push the limits of just how much fire your taste buds can handle, Capsicum chinense boasts many of the hottest cultivars in the world. Every pepper to hold the world record for heat has been a chinense, starting with the Red Savina habanero in 1994. The habanero and the scotch bonnet belong here too.
The species originated in the Amazon basin and spread into the Caribbean long before Europeans arrived. These tropical natives want more heat and a longer season than annuum does, so they take more patience in a backyard garden.
Capsicum baccatum
Capsicum baccatum is one of the easiest species to identify, because it has distinctive coloring on the flowers. Look closely and you’ll see a pair of spots near the bottom of every petal. It includes the popular South American peppers commonly known as ajis, like aji amarillo and aji panca, though some ajis belong to other species.
You’ll want room for them, since the plants grow tall: the monograph puts the domesticated form at roughly 3 to 8 feet. Heat stays moderate, topping out at 50,000 SHU in our list.
Capsicum frutescens
The tabasco pepper belongs to Capsicum frutescens, and it has been going into Tabasco sauce since the late 1860s. Edmund McIlhenny grew his first commercial crop in 1868 and sold his first bottle the next year.
This species also includes the famous malagueta chili pepper from Brazil. Where it was first domesticated is still an open question, with Amazonia and Mesoamerica both in the running. And if you’re short on space, compact varieties like the tabasco suit container gardening.
Capsicum pubescens
Capsicum pubescens is the least studied of the five and the quickest to identify. Want proof? Cut a pod open and you’ll find black seeds, darker than any other domesticated species carries. The flowers are usually purple, and the monograph describes plants of roughly 3 to 10 feet, occasionally taller.
The species includes the Mexican manzano pepper as well as the Peruvian rocoto. And it isn’t known from the wild. Researchers have found it only as a cultivated plant.
Whether you’re planning to grow your own peppers at home, become a more knowledgeable chef when it comes to harnessing the full potential of your favorite peppers, or you simply have an interest in that hard-to-resist palate pleaser in general, just follow the link to an individual Capsicum species to dive in and learn more.
How are the Capsicum species related?
A 2016 phylogenetic study in Annals of Botany sorted the genus into 11 clades, groups of species that share a common ancestor, and the monograph builds on that. The five domesticated species fall into three of them.
Annuum, chinense and frutescens share the Annuum clade, along with the wild Capsicum galapagoense. They’re close enough to cross, and together with their wild forms they make up what breeders call the annuum primary gene pool. The ghost pepper is the famous example: a natural hybrid of chinense and frutescens.
Baccatum shares a clade with two wild species, Capsicum chacoense and Capsicum rabenii. Pubescens sits alone in the Pubescens clade, and its nearest wild relatives, Capsicum cardenasii and Capsicum eximium, belong to the Purple Corolla clade but still cross with it.
Crosses between those three groups are hard. A 2015 paper in PLoS ONE reported little reproductive compatibility among the annuum, baccatum and pubescens gene pools. So breeders after a baccatum and annuum hybrid have had to rescue the embryos in a lab, which isn’t something you’ll manage on a windowsill.
How do you tell the five species apart?
Want to know which species a pepper plant belongs to? Skip the pods, since their shapes and colors cross every species line, and check the flowers and seeds instead. Work down this list in order:
- Black seeds, usually with purple flowers: pubescens.
- Spotted petals, white or cream with marks near their base: baccatum.
- One flower at each node, occasionally two, usually white: annuum.
- Two to four greenish-white flowers at each node, with a pinched ring where the calyx meets the stem: chinense.
- The same flowers without the ring, and usually upright pods: frutescens.
The last three are the hard ones, since annuum, chinense and frutescens overlap and sometimes cross. Still not sure which you’ve got? Our chinense and frutescens pages go into the tricky cases.
Where does Capsicum come from?
South America. That 2016 phylogeny places the origin of the genus along the Andes of western to north-western South America. Its wild species now range from there all the way to the southern United States.
The five domesticated species came later and separately. Annuum was domesticated in Mexico, chinense in the Amazon basin, pubescens in the Bolivian highlands, and baccatum in Bolivia or coastal Peru. Frutescens’s origin is still open.
And how long have people been eating them? Starch grains from chili peppers turn up at archaeological sites in Ecuador from about 6,000 years ago, and the 2007 study in Science that found them argued they were already domesticated peppers. In Mexico, linguists trace a word for chili back roughly 6,500 years.
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Related reading
- Genus vs. species: how the two-part scientific names work, and what each one means.
- What is a chili pepper: the fruit, the name and how hot chilies get.
- The Hot Pepper List: every pepper we’ve profiled, sortable by heat and flavor.
- Ornamental peppers: the decorative chilies, and which of them you can eat.
This is really helpful. Thank you.