Note: Information is dated. Do not rely on it.Caper. The unopened flower bud of a low trailing shrub, which grows from the crevices of rocks and walls, and among rubbish, in the countries bordering the Mediterranean. Picked and pickled in vinegar and salt they are much used as a condiment (caper sauce being especially the accompaniment of boiled mutton). The plant was introduced into Britain as early as 1596, but has never been grown on a large scale. The flower buds of the marsh marigold and the seeds of nasturtium (Tropaeolum) are frequently pickled and eaten as a substitute for capers.