Capparis spinosa Seeds | Caper
LATIN NAME: Capparis spinosa
COMMON NAME: Caper
Plant Profile
The caper bush is a sprawling, half-scrambling shrub, one to two metres across and usually less than a metre tall, with long, trailing branches that root where they touch the ground and hang down over walls and rocks. The leaves are round to ovate, thick, fleshy and blue-green, with a pair of curved spines at the base of each stalk, though the spines vary from fierce to almost absent across the species’ many forms. The whole plant has a loose, untidy, sun-baked look that belongs on a ruin or a dry stone wall rather than in a border.
The flowers are extraordinary and easy to miss, because each one opens in the evening and is finished by the next afternoon. They are white, four-petalled, five to seven centimetres across, with a great brush of long stamens that starts white and ripens to purple, and they are produced in succession over several weeks in early summer. The fruit is an oblong capsule that splits to release kidney-shaped seed in a red pulp, and it is this fruit, picked young, that is sold as the caperberry. The species is native around the Mediterranean, in North Africa and across western Asia, growing on rocks, walls, rubble and dry disturbed ground, and it has followed cultivation so far that its original range is uncertain.
Science & Biotechnology
The buds are chemically interesting for a reason that has nothing to do with their flavour. They are rich in rutin and quercetin, flavonoids with antioxidant and venoprotective activity, and this is why caper extracts appear in supplements aimed at circulation. They also contain glucosinolates, principally glucocapparin, which break down on crushing to methyl isothiocyanate, the pungent compound responsible for the sharp, mustard-like note of a pickled caper. Studies have measured the antioxidant capacity of buds, leaves and fruit, and have looked at the anti-inflammatory and antimicrobial activity of the extracts. The root bark has a separate folk record, used for liver and joint complaints in the eastern Mediterranean.
The pollination biology is a small drama. The flowers open at dusk, produce a strong, sweet scent and a large quantity of nectar, and are visited by hawk moths and by bees that are still flying at last light; by the following afternoon the petals have wilted and the flower is finished. This single-night strategy, combined with the long stamens and the exposed stigma, is characteristic of the family. The seed is hard-coated and dormant, and germination in the wild is often triggered by the abrasion and heat of the rocky sites where the plant grows. The taxonomy of the group is unsettled, with several subspecies and closely related species recognised across the Mediterranean and Asia, and the spiny and spineless forms have been treated variously as varieties and as separate taxa.
Uses & Benefits
Capers are the unopened flower buds, picked by hand in the early morning, graded by size and pickled in vinegar or brine. The smallest grades are the most expensive and the most intense. Caperberries are the young fruits, picked with the stem attached, and they are milder and crunchier. Both are used across Mediterranean cooking, in sauces, salads, pasta, fish dishes and as a garnish, and the saltiness and acidity make them a useful counterpoint to rich food. The buds are also sold dry-salted, which concentrates the flavour further and requires rinsing before use.
The plant has a place in a dry garden as a wall shrub or a ground cover on rough, stony ground, where its trailing habit and blue-green foliage are an asset and its untidiness does not matter. It is also grown commercially in Spain, Italy, Morocco and Turkey, usually on marginal land where nothing else will pay. In cool climates it can be grown in a large pot, moved under cover for winter, and pruned hard each spring, which keeps it compact and encourages the production of buds. It is drought-tolerant to the point of resenting irrigation, and it flowers best in a hot, exposed position.
Growing from Seed
The seed coat is hard and germination is slow and uneven without help. Soak the seed in warm water for twenty-four to forty-eight hours, then nick the coat with a file or rub it on sandpaper, and sow into a gritty, free-draining mix at twenty to twenty-five degrees. Germination begins in two to six weeks and may continue for three months. A treatment with gibberellic acid improves the result. Keep the mix on the dry side, since the seed rots easily, and give full light as soon as the seedlings appear.
Grow the seedlings on in deep pots of gritty compost, in full sun, and do not overwater. Plant out in spring into a hot, dry, stony site with sharp drainage, or keep the plant in a pot in cooler climates and move it into a cold greenhouse for winter. Prune the previous year’s growth back hard in early spring to keep the plant compact and to stimulate new shoots, which carry the buds. The plant flowers from its second or third year, and the buds should be picked while they are still tight. It is short-lived in cultivation, usually ten to fifteen years, and is best replaced from cuttings or seed before it declines.
Our Take
A caper bush is worth growing for the flowers alone, and the pickled buds are a bonus that pays for the space. Give it heat, grit and neglect, and it will outlive most of the garden.
Related Reading
Readers interested in Caper frequently explore these as well: