Q. Are there more varieties of beans than there used to be?

A. The International Center for Tropical Agriculture preserves the seeds of nearly 40,000 bean varieties, many of which were first domesticated from wild types thousands of years ago in the tropical New World.

Only a few of these varieties, however, are in wide agricultural production. Like many fruit varieties, including several types of apples, beans in many older forms have been lost over the years and are no longer cultivated.

But agricultural scientists are actively developing new varieties, notably beans that are resistant to disease or drought, or have higher levels of nutrients like iron and zinc. These are especially important in Latin American countries, where beans are a staple of the diet.

The common bean, Phaseolus vulgaris L., was introduced to Europe in the late Middle Ages from what are now Mexico, Central America and the Andes, bringing another cheap source of protein to long-established legumes like lentils and broad beans.

As many as two-thirds of the many European varieties have genetic origins in the Andes. Subsequent hybridization with Mesoamerican types increased the diversity of beans across the continent.

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