Runner bean

The runner bean is a perennial vine in its native range, though it is grown as an annual in cooler climates. It climbs by twining to heights of two to three metres or more and bears showy clusters of scarlet, white or bicolour flowers that attract bees and hummingbirds. The pods are rough and long, sometimes 30 cm, and the seeds inside are large and kidney-shaped, coloured black, purple, pink or mottled, and white in some cultivars. Young pods are eaten as green beans; mature seeds are shelled and dried. The root of the plant is thick and starchy and was historically eaten.

Runner bean is native to the highlands of Mexico and Central America, where wild populations grow in cool, moist mountain forests. It was domesticated there thousands of years ago, alongside the common bean and maize, and is still grown by farmers in Mexico and Guatemala under names such as ayocote. It reached Europe in the seventeenth century, initially as an ornamental, and does best in cool and moist summers because high heat can cause its flowers to drop without setting pods. This is one reason it became so important in the UK and northern Europe.

Runner beans were grown in Mesoamerica long before European contact, as part of the milpa or the three sisters-type plantings with maize and squash. Spanish explorers brought seeds to Europe, where the plant was first treated as a garden ornament. By the nineteenth century, British gardeners had turned it into a favourite pod vegetable, and it is a classic of English allotments and vegetable shows.

In Mexico and parts of Central America, the large dry seeds, often called ayocotes, are still valued as a food for stews and soups, and are sold in markets in several colours. Seed saving and the genetic diversity of landraces are important, and conservation groups and growers work to maintain traditional varieties.

Young runner bean pods are sliced and steamed or boiled as a side vegetable, or added to stews and curries. Mature seeds are shelled and cooked fresh or dried, and are simmered for a long time into soups, stews and bean dishes similar to those made with kidney or butter beans. In Mexico, ayocote beans are cooked with herbs and chiles. The flowers are edible and used as a garnish in salads. Dry beans must be soaked and fully boiled before eating.

Runner bean seeds, like other beans, provide plant protein, complex carbohydrates, fibre, folate, iron, magnesium and potassium. Green pods supply vitamin C and vitamin K in smaller amounts and few calories. Nutrient values vary between varieties and in the way beans are prepared, so the numbers given are approximate. Beans and pulses as a group are a core part of many healthy dietary patterns and can replace more energy-dense or heavily processed foods.