Commonly known as caper, caperberry or caperbush, Capparis spinosa is a scrambling perennial shrub perhaps native to southern Europe, northeastern Africa including Madagascar, southwestern and central Asia, Australia and Oceania. It is thought to be an archaeophyte, or a plant introduced to some of these areas in ancient times. Its country of origin is unknown, but some have speculated that caperbush may have first come from the Mediterranean region.
Caperbush grows quickly, producing new stems each year from a woody base as well as many branches. Mature plants are typically 1 to 1.5m tall and 2 to 3m wide. The glossy dark-green fleshy leaves are round to ovate, and arranged alternately on the stem. A sharp pair of spines grows from the base of each petiole, earning the plant its specific epithet, spinosa.
The fragrant white blossoms unfurl on first-year branches from May to September. Five to eight centimers in diameter, each perfect flower bears a single stigma surrounded by many vivid purple stamens. New flowers open in the early morning and wilt by the middle of the day, after being pollinated by insects. The dehiscent ripe fruits or berries contain large grey-brown seeds that are shaped like kidneys.
Capparis spinosa thrives in nutrient-poor soils. The species is tolerant of drought and salt spray. It is often found growing on embankments, in rocky seaside areas and in the crevices of stone structures, where its extensive root system firmly anchors it to the rock. Caperbush grows best in dry heat and strong sunlight. It is hardy only to -8ºC, nor can it survive in shady areas.
Caper plants have been a part of cuisine and medicine since ancient times. The carbonized remains of caper plants, dated between 9500 BC and 400 BC, have been found in Iraq, Syria and Greece. Dry clumps of caper seeds estimated to be 2800 years old were recently discovered in the Yanghai Tombs in the Turpin District, Xinjiang, China (see: Jiang, H-E. et al. (2007). The discovery of Capparis spinosa L. (Capparidaceae) in the Yanghai Tombs (2800 years b.p.), NW China, and its medicinal implications. Journal of Ethnopharmacology. doi:10.1016/j.jep.2007.06.020 ). While not the oldest remains to be discovered, the seeds from the Yanghai Tombs are remarkably well-preserved and likely indicate the medicinal use of capers in ancient China. In 1st century Rome, Pliny the Elder listed eighteen remedies that could be prepared using parts of the caper plant, including remedies for toothache, “affections of the spleen”, ear ache, diseases of the bladder, tapeworms, and certain kinds of ulcers. The flower buds are said to have anti-inflammatory properties and are traditionally used to treat rheumatism.
Capparis spinosa is commercially grown in Italy, Spain, France and Algeria for its immature flower buds, which make a sharp accompaniment to Mediterranean dishes when cured in salt or vinegar. Commercially-grown cultivars of Capparis spinosa are generally spineless with compact, flavourful flower buds. One three-year-old shrub can produce 1-3 kilograms of flower buds each harvest season. The buds are harvested early in the morning on dry days. They are then washed with saltwater, wilted, and preserved by pickling or salting. The buds are sorted according to size, with the smallest capers considered to be the highest quality. Their flavour, which can be described as a cross between mustard and black pepper, is derived from mustard oil (methyl isothiocyanate). This is released from glucocapparin molecules during the curing process. The cured flower buds or capers are used in a variety of dishes including pastas, meats, fish, and sauces. It is recommended to rinse the capers in cold water before use so that their peppery taste is not overcome by the taste of the pickling brine.
Other parts of the caper plant are also edible: the young shoots are sometimes pickled or cooked like asparagus, while the ripe and unripe berries may be pickled, cooked as vegetables or made into sauces. Ash from the burned roots has been used as a form of salt.