The jalapeño is a medium-sized chili pepper

Chili pepper

Chili pepper is the fruit of plants from the genus Capsicum, members of the nightshade family, Solanaceae. The term in British English and in Australia, New Zealand, India, Malaysia and other Asian countries is just chilli without pepper.Chili peppers originated in the Americas...

 that has a warm, burning sensation when eaten. A mature jalapeño fruit is 2–3½ inches (5–9 cm) long and is commonly picked and consumed while still green, but occasionally it is allowed to fully ripen and turn crimson red. It is a cultivar

Cultivar

A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...

 of the species Capsicum annuum

Capsicum annuum

Capsicum annuum is a domesticated species of the plant genus Capsicum native to southern North America and northern South America. The three species C. annuum, C. frutescens and C. chinense all evolved from a single common ancestor located somewhere in the northwest Brazil - Colombia area...

originating in Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, which is a bush that grows 2–4 feet (60–120 cm) tall. It is named after Xalapa, Veracruz, where it was traditionally cultivated.