This is a group of 4 genera and about 25 species of herbaceous perennial vines. They originated primarily from the tropical areas of South America and Central America.

Note on Taxonomy - Plant taxonomy is the art and science of classifying plants into groupings in order to help people make sense of the huge diversity found in the world. The people who do this for a living are called taxonomists. They are continually evaluating and re-evaluating how plants are classified. For example, with the recent emergence of DNA analysis, many plants have been changing classification.

Also, there is no one, single universal classification system for plants. Rather, there is a lot of debate among taxonomists which may lead to confusion for the average gardener. That is why, in these family listings, you often see the words "about" or "around" when counting the number of genera or species to include. It is also why new families are created and some of the old ones suddenly fade away. So, don't be surprised if you find slightly different information at other sites or sources. Oh, well.