The hyacinth bean

In the early fall of 1993, I visited Monticello one sunny afternoon to take photographs for a future lecture at UNCA’s College for Seniors. And whatever other memories I have of that trip, few are sharper than the sight of the arbors made of black locust at the southwest corner of Jefferson’s 1,000-foot-long vegetable garden terrace — literally entwined from toe to tip with the bountiful blooms and seedpods of that glorious climber, the hyacinth bean.

The estate’s Garden Book for the year 1812 describes the vines as “arbor beans white, scarlet, crimson, purple … on the long walk of the garden.” And though Jefferson doesn’t mention it by name, this tender perennial vine is such a showstopper (and so important as a vegetable crop worldwide) that it must have been on the estate, especially because his favorite nurseryman, Bernard M’Mahon, listed the seeds in his collection.

The scientific name, Dolichos lablab, comes from “dolichos” (the Greek word for “long” — referring to the stems) and “lablab,” the Egyptian name for the beans.

Common names for the hyacinth bean abound; they include: dolichos bean, Egyptian bean, zaramdaja, lablab, bonavista bean, bovanist bean, seim (or sem) bean, Indian bean, frijole caballero, Chinese flowering bean, pharaoh’s bean — and, in many parts of China, pig’s ears (referring to the shape of the leaves). Originally from tropical Africa, the plant is now cultivated around the world, usually for food but often as an ornamental. It’s very popular in China, where it has been grown on backyard fences and trellises for centuries.

Many seed catalogs incorrectly list it as an annual vine, but it’s a true perennial — and, like many tropical perennials, it blooms the first year from seed. This twining vine has purplish stems and alternate, pinnately divided leaves with three large leaflets. In a good season, it can grow 20 feet. The fragrant white, pink or purple pea-shaped flowers grow in elongated clusters. They are followed by a fruit the color of a rare violin that opens to reveal three to five black seeds with a conspicuous white hilum (the elongate scar on the edge of the bean where it was attached to the inside of the pod). The fruit is also fragrant.

Several cultivars have been selected, including some with white flowers and pale green pods; some with red flowers; some with long, thin, cylindrical pods; and some dwarf forms. Many are day-length-neutral, but most selections still flower as day length shortens — making them stellar additions to the late-summer garden. Well-planted vines will produce hundreds of spikes, each crowded with lavender flowers and yielding hundreds of pods. The distinctive, long-lasting pods are suitable for the cut-flower industry.

The young pods and beans are used in the production of many Oriental foods, but they should be avoided unless you know precisely how to prepare them. To most Western noses, the beans give off an unpleasant odor when cooking (though it should be noted that while many Americans find ginkgo fruits violently unpleasant, people of Asian extraction often adore them — and then there’s kimchee). Unfortunately, the purple color disappears during cooking. Some books claim that young leaves are eaten raw in salads, while older leaves must be cooked like spinach. The large, starchy root tubers can be boiled and baked.

If you plan to cook with the dried, mature seeds, special care is needed: They contain toxic levels of cyanogenic glucosides and must be boiled in two or more changes of water before eating. In Asia, the mature seeds are made into tofu and fermented for tempeh. They’re also used to make bean sprouts — and as livestock fodder.

Hyacinth beans are easy to grow, but unless you live in a very warm climate, start the seeds about eight weeks before the last frost by putting three beans in a 4-inch peat pot. When the seedlings are about 6 inches high, pull up the two weakest plants. And when planting the survivors, do not disturb the root ball. Alternatively, you can set out seeds directly when the soil is above 65 F. These climbers also need a good tilth, but remember: They do best in alkaline or calcareous soils. If planting them out in an acid soil, remember to add some lime to it. And like most tropical vines, once they’re established, they’ll need occasional feedings with a good liquid fertilizer. Provide full sun.