Capsicum

Capsicum is the genus that every chilli and every sweet pepper belongs to. It sits inside the Solanaceae, the nightshade family, alongside tomatoes, potatoes, aubergines and tobacco.

A genus is a branch, not a kind of plant. Within Capsicum sit dozens of species, five of which people domesticated, and within each species sit hundreds of named varieties. That is how a sweet bell pepper and a Carolina Reaper end up as relatives: one is Capsicum annuum, the other Capsicum chinense.

The five domesticated species

• Capsicum annuum for bell peppers, jalapeño, cayenne, Padrón and most Thai chillies. The most grown, and the most forgiving in a British summer.
• Capsicum chinense for habanero, Scotch bonnet and nearly every superhot. Slow and demanding.
• Capsicum frutescens for Tabasco, Malagueta and some bird's eye types. Closely related to chinense.
• Capsicum baccatum for the South American ajís. Spotted flowers, tall plants, fruity heat.
• Capsicum pubescens for rocoto and manzano. Purple flowers, black seeds, cool-tolerant.

The rest of the genus is wild. A few of those, the chiltepin among them, are picked and eaten where they grow without ever having been formally domesticated.

Capsicum does not mean hot

Sweet peppers are Capsicum. So is paprika. Heat comes from capsaicin and its related capsaicinoids, and non-pungent peppers have been selected over centuries to make almost none of it. A bell pepper is not a different sort of plant from a habanero. It is the same species as a jalapeño with the heat bred out.

One note on usage: in Britain, Australia and India, "capsicum" in a shop or a recipe usually means a sweet bell pepper specifically, not the genus. This page is about the genus.