Gandule is another name for pigeon peas (Cajanus Cajan). Pigeon peas are a small bean that are native to Africa and/or India but most likely originated in India and were brought to Africa millennia ago, where many different strains were developed.
Pigeon peas are also called goongoo beans, Congo beans (Jamaica), no-eyed peas, Red gram, kardis, Pois d’Angole(French West Indies); guandu or andu(Portugese Brazil) and many other names.
The beans are small, green to yellow-brown, and highly nutritious. They are used as both a vegetable and dried for use as a flour. In India, they are used as a split pea or “dhal” in soups. In many countries, they are commonly eaten with rice. They are also dried and fermented to make dhokla and tempeh.
In specialty markets they can be found canned, frozen, and dried and are easily found canned in U.S. grocery stores, such as the Goya brand. You may find both green canned gandules, or gandules verdes, or dried canned gandules, or gandules secos. The difference is that the green version was harvested green and canned fresh, and the dried version was dried before soaking and canning. Some dried versions might be allowed to sprout slightly before cooking. Either way, the dried versions, which look more brown, will have a different flavor.
The name gandule is common in the Spanish Caribbean, where various rice and pea dishes called arroz con gandule are staples. They are especially popular in Puerto Rico and Cuba.
Cajanus cajan, the sole member of its genus Cajanu indicus, is grown and eaten all over the Eastern Caribbean, where they are a basic subsistence crop. They thrive in dry tropical areas and in sandy soil and are found throughout tropical and subtropical regions, but are also comfortable in warmer temperate climates. They are quite drought resistant. The closest wild relative, Atrylosia cajanifolia Haines, is found in some places in East India but cajanus cajan is never found truly wild, existing solely as a cultivated crop. Some may persist in uninhabited areas where they were once cultivated. The plants are perennial woody shrubs which can grow up to 4 meters tall.