Canavalia spp.

jack bean

Fabaceae

Pantropical (tropical Americas, Africa, Asia, and Pacific coasts)

Attracts Pollinators Attracts Butterflies Drought Tolerant

Native to North America

SunFull Sun

WaterMedium · drought-tolerant

HardinessZones 9–12

Overview

Canavalia spp. is a pantropical genus of about 50 legume species in the pea family (Fabaceae), most of them twining or trailing vines and a few bushy subshrubs. Stems run 3-30 feet (1-9 m) depending on species, climbing over other plants or trailing across open ground and dunes. The leaves are divided into three broad leaflets, each 2-8 inches (5-20 cm) long, on long stalks. Pea-shaped flowers 1-1.5 inches (2.5-4 cm) long open in pink, rose-purple, or white along upright stalks, held upside down in the way typical of the genus. These are followed by large flat pods 4-14 inches (10-35 cm) long holding several big, hard seeds. Coastal species such as C. rosea bind sand on tropical beaches, while C. ensiformis, the jack bean, and C. gladiata, the sword bean, are grown in warm regions as cover crops, fodder, and cooked vegetables. The raw seeds contain canavanine and the protein concanavalin A and are toxic until thoroughly cooked. Most species need year-round warmth and are killed by frost, and the heavy vines can smother nearby plants if left unchecked.

Native Range

The genus is spread through the tropics and subtropics of the Americas, Africa, Asia, and the Pacific. Several beach species, including Canavalia rosea, are native to the southern coasts of North America, while the cultivated jack bean and sword bean are grown across the warm parts of the world.

Suggested Uses

Across the genus, species are used as cover crops, green manure, and livestock fodder, and the cooked beans of the jack bean and sword bean are eaten in many warm regions. Coastal kinds are planted to stabilize dunes and sandy banks. As ornamentals the larger-flowered vines are grown on fences and trellises in frost-free gardens.

How to Identify

Look for a robust legume vine with leaves split into three broad leaflets and large pea flowers in pink to purple, set so the keel points upward. The pods stand out: flat, leathery, and 4-14 inches (10-35 cm) long, with a ridge running along one side and several large seeds, each marked by a long pale scar. Beach species trail over sand with thick, fleshy leaflets, while crop species form bushier or strongly twining stems.

Appearance

Size & Dimensions

Height3' - 30'

Width/Spread3' - 10'

Reaches mature size in approximately 1 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~12 weeks

Summer Fall

In warm climates the genus flowers through summer and autumn, and nearly year-round in the wet tropics. Flowers open a few at a time along upright stalks over many weeks. Pods follow quickly and enlarge in the weeks after each flush.

Detailed Descriptions

Flower Description

pink, rose-purple, or white

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.0 - 7.5(Neutral)

357912

Soil Types

sand loam

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

tender

Time to Maturity

flowers in one warm season

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Plants grow in full sun on light, well-drained soil, including the sand and poor ground where many species occur naturally, across a pH of about 5.0 to 7.5. Warmth through the season is needed, as frost kills the vines and growth slows in cool weather. Established plants withstand drought and salt spray, traits strongest in the coastal species. As nitrogen-fixing legumes, they grow on lean soils and are used to enrich ground as green manure. The fast, heavy vines need a sturdy support or open space to run, since they can overwhelm smaller plants. Seeds germinate readily after the hard coat is nicked or soaked.

Pruning

Vines are cut back to hold them in bounds and to clear spent growth at the end of the season. Crop species are often topped to encourage branching and heavier podding. Where grown as green manure, the whole stand is cut and turned into the soil before the pods harden.