Abrus precatorius

Rosary pea

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Introduction

There are many uses for rosary pea. The seeds have been used in all types of jewelry and can also be used as a contraceptive or to treat diabetes and chronic nephritis. Roots are used to induce abortion and against abdominal discomfort. Interestingly, one of the most deadly plant toxins, abrin, is produced by Abrus precatorius. Even though rosary pea seeds are highly toxic, in certain parts of the world the seeds are boiled and eaten. Boiling destroys the toxins contained within the seed, rendering them safe for consumption. Toxins are released only if the seed is chewed and swallowed and the seed is the only part of the plant that is poisonous. As little as 0.00015% of toxin per body weight will cause fatality in humans (a single seed).  In case of accidental ingestion, a suggestion to alleviate any ill effects of the toxins is to administer fluids and electrolytes.  

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Description

Rosary pea is a small, high climbing vine with alternately compound leaves, 2-5 inches long, with 5 to 15 pairs of oblong leaflets. The flowers are small, pale, and violet to pink, clustered in leaf axils. The fruit is characteristic of a legume. The pod is oblong, flat and truncate shaped, roughly 1½ - 2 inches long. This seedpod curls back when it opens, revealing the seeds. The seeds are small, brilliant red with a black spot. These characteristics give the plant another common name of crab’s eyes.
Interestingly, birds seem to be unaffected by the deadly toxin because they readily disperse Rosary pea seed. Roots grow very deeply onto the ground and are very difficult to remove. Fire encourages the growth of Rosary pea. 

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Impacts

Rosary pea is found throughout central and southern Florida, including Marion, Lake, Palm Beach, and Manatee counties. All together, rosary pea has been collected from 27 counties throughout Florida.  Undisturbed pinelands and hammocks are often invaded by Abrus. The Florida Exotic Pest Plant Council considers rosary pea a category 1 invasive species due to its ability to invade and displace native plant communities. Characteristic of a vining plant, rosary pea can grow over small trees and shrubs.

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Management

Preventative:

Regular monitoring and rouging of plants can prevent the spread and establishment of rosary pea.  Programs to educate homeowners on proper plant identification will also reduce the spread of this species.

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Cultural:

Native alternatives to rosary pea for use in home landscaping or natural areas include leather flower (Clematis crispa) or Carolina jessamine (Gelsemium sempervirens).

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Mechanical:

Hand-pulling and removal of entire plants, particularly the roots, is practical for small infestations.  Aggressive tillage is an option and very effective, but impractical in many areas.  Fire provides only temporary control.

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Biological:

There are no known biological agents for rosary pea.

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Chemical:  

Timing of application is critical to effectiveness; with applications in the fall prior to seed set being the most effective. Triclopyr is effective on large woody vines immediately after the vines are cut down. Triclopyr amine or glyphosate can be applied to the foliage at 3-5% or 1-3%, respectively. 

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Helpful Notes:

Surfactant – 0.25% is the standard rate for all foliar herbicide applications, 2 teaspoons per gallon.

Dry time – generally 4-6 hours is adequate, but the longer the better for glyphosate

Pay particular attention to herbicide labels near wetlands or bodies of water.

The use of trade names in these publications is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label.

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References and Useful Links:

USDA Natural Resources Conservation Service. Plants Database

Invasive Plants of the Eastern United States

University of Florida Center for Aquatic and Invasive Plants

Langeland, K.A. and K. Craddock Burks. 1998. Identification and Biology of Non-Native Plants in Florida's Natural Areas. IFAS Publication SP 257. University of Florida, Gainesville. 165 pp.

The Plant Conservation Alliance's Alien Plant Working Group. Weeds Gone Wild: Alien Plant Invaders of Natural Areas

Pacific Island Ecosystems at Risk (PIER). Plant Threats to Pacific Ecosystems

Floridata Homepage

The Hillsborough County Invasive Species Task Force
Identification and control of non-native invasive plants in the Tampa Bay Area

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