Caper

a trailing shrub growing on old walls, rubbish heaps, and the like in Mediterranean countries. The unopened flower buds when put down in vinegar are called capers. These pickles are much used, especially in making caper sauce to serve with boiled mutton. The taste is sharp and bitter, quite unpleasant to those not accustomed to it. Travelers speak of the profuse white and purple flowers as an ornament of the rubbish heaps and ruins of the Levant.