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Scientific: Vigna caracalla (Synonym: Phaseolus caracalla)
Common: snail vine, snailflower, corkscrew flower, corkscrew vine
Family: Fabaceae
Origin: Tropical New World

Pronounciation: VIG-na car-a-CALL-la

Hardiness zones
12-24, elsewhere as an annual
USDA 9-11, elsewhere 1-8 as an annual

Landscape Use: Trellis, arbor, green walls (with support) both short and tall, and as a fence covering.

Form & Character: Trailing, twining, climbing, rambling, tender and delicate, yet sneaky aggressive and tough, tropical.

Growth Habit: Snail vine is an evergreen, herbaceous perennial vine that is a vigorously twines to 100-feet long. It needs structural support such as a fence or trellis to twine upon. It is an escape artist, so beware of it spreading into landscape areas not wanted.

Foliage/Texture: Alternate, trifoliate (three leaflets/leaf) leaf, leaflets ovate to lanceolate to 3-inches long; medium texture.

Flowers & Fruits: White, pink to bluish purple (most common), classic pea flower, flower buds have a distinct hooked spur or keel, sometimes fragrant; fruit is an unattractive linear pod to 7-inches long.

Seasonal Color: Flowers heavily during spring, and then sporadically during summer.

Temperature: Cold sensitive, subject to chilling injury below 40oF.

Light: Partial shade to full sun when mature. Performs poorly (reduced vigor, poor leaf color) when grown in direct western afternoon sun in Phoenix.

Soil: Tolerant

Watering: Apply irrigations regularly throughout the year, drought sensitive but use water to control the vigorous growth of this vine.

Pruning: Shear or head back vigorously to control spread, and observe spread carefully as snail vine can escape and infiltrate nearby shrubbry.

Propagation: Asexually by softwood cutting under high humidity, seed.

Disease and Pests: None

Additional comments: This is a nice, but extremely ("DANGER Will Robinson!! ...DANGER!!") vigorous vine for a tropical landscape effect where purple blue flowers are wanted to give a subtle cooling effect. Snail vine can occassionally freeze to the ground during the Phoenix winter but will rapidly re-grow in the spring.

Taxonomic tidbits: Vigna contains over 200 species and is closely related to the genera Phaseolus and Hardenbergia. The species name caracalla was derived from the Spanish and Portuguese word "caracol", which means snail.