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| Category: Vine |
| Family: Fabaceae = Pea Family |
| Origin: South America |
| Flower Color: Purple |
| Bloomtime: Summer/Fall |
| Fragrant Flowers: Yes |
| Synonyms: [Vigna 'Thomas Jefferson', Phaseolus caracalla] |
| Height: Climbing (Vine) |
| Width: Spreading |
| Exposure: Full Sun |
| Irrigation (H2O Info): Medium Water Needs |
| Winter Hardiness: 25-30° F |
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Cochliasanthus caracalla (Corkscrew Vine or Snail Vine) - A fast growing tender twining vine growing from tuberous roots that can clamber upon support to heights 15 to 20 feet. It has soft, dark green trifoliate leaves. In summer to early fall it produces masses of fragrant large (1-2 inch) flowers that are white streaked with pale purple that age to a light yellow and maroon with petals that are curled to give a snail-like appearance. Such is the heady aroma of this plant that it is often compared to that of a hyacinth, jasmine or lilies. After flowering it produces green bean pods in later fall. Plant in full to part sun and irrigate regularly. It is hardy to around 25 °F and useful as a semi-evergreen vine when grown in a climate without frost and also used effectively as an annual in colder climates. An attractive vine with wonderfully fragrant flowers that can perfume large areas and is attractive to bees and butterflies. Foliage yellows and drops in late fall in Santa Barbara - trim back in early spring to clean up winter deciduous stems and to maintain size. The native range of Vigna caracalla is Southern Mexico south through Central America and tropical South America and the genus is considered to be monotypic, with only this one species, though previously it was considered to belong to the genus Vigna and before this in the genus Phaseolus. The plant was brought back to Portugal from Brasil in the late 17th century and first described by Linnaeus in 1753 as Phaseolus Caracalla. It was later reclassified as Vigna caracalla by Bernard Verdcourt in 1970 (Kew Bulletin v24 n3) but the most current name is Cochliasanthus caracalla which was the name ascribed to the plant by the German physician and botanist Christoph Jakob Trew in 1763 but the name only resurrected after more recent genetic studies indicated its differences with Vigna. The genus name Vigna is named after Dominico Vigna an Italian botanist of the 17th century and the name Cochliasanthus is thought to refer to the snail-like shape of the flower, which is a similar shape as the cochlea in the inner ear. The multiple name changes and variability of forms of this plant has caused considerable confusion, particularly with an invasive plant often called Phaseolus giganteus, or Vigna speciosa (and now Sigmoidotropis speciosa), which is similar but has lavender colored non-fragrant flowers. Though some note that the specific epithet is a reference to Caracas, Venezuela, it is thought that the name really it is a corruption of the Portuguese word for snail, which is "caracol". Common names for the plant include Bertoni Bean, Corkscrew Vine, Snail Flower, Snail Vine or Snail Bean. The reasons for most of these names is self-evident but the common name Bertoni Bean comes from a collection of the plant, then described as Phaseolus carcalla, from Paraguay at Puerto Bertoni which was named for the Swiss Botanist Moses S. Bertoni (1875 - 1929). This collection was recorded by the USDA Bureau of Plant Industry in their inventory of Seed and Plants inported in 1916 as SPI 41882. Interestingly Dr. Franceschi (AKA Emanuele Orazio Fenzi) introduced into the Santa Barbara nursery trade a plant he called Phaseolus bertonii (SPI 37010) that he received from Paraguay and this name s now considered synonymous. Thomas Jefferson called this plant "the most beautiful bean in the world". The Jefferson Monticello website entry notes that in 1792 Jefferson noted that the Caracalla Bean was "The most beautiful bean in the world is the caracalla bean which, though in England a green-house plant, will grow in the open air in Virginia and Carolina." It was further noted on the Monticello website that the plant was introduced into European gardens in the eighteenth century but it was unclear whether Jefferson ever received seeds or plants, however it was in cultivation in the US by the 1830s, when Robert Buist wrote in The American Flower Garden Directory "Phaseolus caracalla (syn. Vigna caracalla), or Snail-Flower is a very curious blooming plant, with flowers of a greenish yellow, all spirally twisted, in great profusion when the plant is well grown." Because of these references to this plant by Jefferson, this plant is sometimes listed by nurseries as Vigna 'Thomas Jefferson'.
This information about Cochliasanthus caracalla displayed is based on research conducted in our horticultural library and from reliable online resources. We also will relate observations made about it as it grows in our nursery gardens and other gardens we have visited, as well how the crops have performed in containers in our nursery field. We will also incorporate comments that we receive from others and we welcome hearing from anyone with additional information, particularly if they can share any cultural information that would aid others in growing it.
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