The following excerpt is from: Maricel E. Presilla, Peppers of the Americas: The Remarkable Capsicums That Forever Changed Flavor. Published by Ten Speed Press, 2017.
Ebook ISBN 9780399578939
Hardcover ISBN 9780399578922
Pepper plants defy quick generalizations based on appearance. The more than thirty-five wild and domesticated species grow in a fantastic range of forms. They can be spindly stalks less than 2 feet/.60 meters high, many-branched and woody like small trees, or dense bushes. The peppers that they bear can be equally confusing to the eye. Lookalikes are often only distantly related. If you have ever had trouble sorting out the kinds in a market display, you are not alone. Nevertheless, wild and domesticated peppers of all species have certain ancient structural traits in common in contrast to more recently acquired features that differentiate, say, a poblano from a habanero. Though we eat them as vegetables or condiments, all are technically fruits or, more specifically, berries, with small seeds borne inside a fleshy envelope. In everyday usage, the fruits are called pods.
Pepper Anatomy: Pod, Calyx, Flower, Seed
In all pepper plants, from tall old shrubs to tender garden specimens, the flowers and, later, the fruits are attached to the branching stems by pedicels (the botanical term for short individual stems) in either erect, pendant (hanging), or intermediate positions. A green calyx first encloses the flower bud, and remains around the base of the opened blossom and then the fruit when it develops. Both flower and calyx display particular features that differ by species. These have been of great importance to botanists who study wild or domesticated peppers in tracking the New World travels of the Capsicum genus’s individual members.
Pepper pods can have remarkably diverse shapes, resembling string beans or diminutive bananas, cherry tomatoes, or miniature lanterns, and botanists have selected particularly illustrative pod types from known cultivars as examples. The kinds closest to the original wild prototype always look like tiny beads. But all peppers, both wild and domesticated, retain parts of the same ancestral anatomy. Their kinship is clear when you compare cross sections or lengthwise sections of different kinds.
Every pepper contains a fleshy outer structure called the pericarp, which you will recognize as the only part of a bell pepper (and some other large peppers) that is eaten. It consists of three layers: the exocarp (skin), the thicker and meatier mesocarp, and the thin, membranous endocarp. On the inner side, the pericarp has two, three, or four lengthwise ridges called ribs, or more precisely septa (from the Latin for “partitions”). These run down all or part of the pod and loosely divide the interior into chambers, or in botanical terms locules or lobes. (In very small, skinny peppers, the ribs may be colloquially called veins.) The chambers that they form are partly hollow, which makes some peppers (especially large ones) ideal for stuffing.
The crucial contents of the pod’s interior are the reproductive organs of the fruit. Starting from the top end, the most conspicuous feature is a pulpy structure called the placenta, which supplies nourishment to the developing seeds just as a mammalian placenta nourishes the fetus. In some kinds, such as the familiar bell pepper, the placenta-seed complex may look like a whitish plug attached to the top; in others, as for the Peruvian ají amarillo, it runs the entire length of the pepper. The number of seeds carried on the placenta varies strikingly between different kinds of peppers, from about a dozen to more than two hundred per fruit.
In every wild species and almost all domesticated cultivars, tiny cells lying close under the surface of the placenta secrete a unique chemical weapon. This fiery substance, produced by capsicums and no other plants, has often been labeled capsaicin. Today it is known to be a complex of several alkaloids more correctly called capsaicinoids. (The pericarp contains another group of related compounds called capsinoids, responsible for the nonhot flavors that are most pronounced in “sweet” cultivars.) It used to be thought that the placenta was the only source of true pepper heat, partly communicating its fierceness to the flesh, veins, and seeds. However, recent research by horticulturist Paul Bosland at the Chile Pepper Institute in New Mexico, has established that in a few superhot cultivars, capsaicin secretion also occurs in the pericarp, meaning that every bit of the flesh can be as incredibly searing as the placenta itself.
