Piper, the pepper plants or pepper vines, is an economically and ecologically important genus in the family Piperaceae.
Piper species have a pantropical distribution, and are most commonly found in the understory of lowland tropical forests, but can also occur in clearings and in higher elevation life zones such as cloud forests; one species – the Japanese Pepper (P. kadsura) from southern Japan and southernmost Korea – is subtropical and can tolerate light winter frost. Peppers are often dominant species where they are found.
Most Piper species are either herbaceous or vines; some grow as shrubs or almost as small trees. A few species, commonly called "ant pipers" (e.g. Piper cenocladum), live in a mutualism with ants. The fruit of the Piper plant, called a peppercorn when it is round and pea-sized, as is usual, is distributed in the wild mainly by birds, but small fruit-eating mammals – e.g. bats of the genus Carollia – are also important. Despite the high content of chemicals that are noxious to herbivores, some have evolved the ability to withstand the chemical defenses of pepper plants.
Many pepper plants make good ornamentals for gardens in subtropical or warmer regions. Pepper vines can be used much as ivy in temperate climates, while other species, like lacquered pepper (P. magnificum) grow as sizeable, compact and attractive shrubs with tough and shiny leaves. Smaller species, like Celebes pepper (P. ornatum) with its finely patterned leaves, are also suitable as indoor pot plants.
The scientific name Piper and the common name "pepper" are derived from the Sanskrit term pippali, denoting the long pepper (P. longum).