Taxonomically speaking, the jalapeño is a specific variety, Capsicum annuum var annuum Linne,
of the chile pepper Capsicum annuum.
Shaped rather like an irregular cylindrical cone, it grows to 2-3 inches in length and 1.5 inches maximum diameter, and its green color will eventually turn bright red if allowed to ripe
n fully. In practice, "jalapeño" can refer to any of several small, green chiles of the genus Capsicum
which are physically similar to the Capsicum annuum.
Jalapeños are grown in, and are a traditional component of the cuisine of, Mexico and the Southwestern United States. The name originated from the city Jalapa in the Mexican state Veracruz. Mexicans reserve the term jalapeño for pickled peppers; fresh ones are denoted by specific variety. The peppers are often preserved by smoking as well; in this state they're known as chipotle, from a Nahuatl word meaning "smoked chile."
The jalapeño's well-known "hot" flavor comes from the chemical capsaicin and the related dihydrocapsaicin. In higher concentrations, capsaicin (usually derived from peppers) can produce severe, though temporary burning sensations and is the active ingredient in self-defense "pepper sprays." Capsaicin is produced in the plant's placenta, which is approximately sixteen times hotter than the rest of the pepper, and usually removed before consumption along with the seeds. It has many medicinal properties, including antibiotic and anti-inflammatory, which made the jalapeño useful as a traditional folk remedy.