Family: Fabaceae

Origin, Description & Uses

Cyamopsis tetragonoloba, commonly known as cluster bean or guar, is an annual legume native to arid and semi-arid regions of South Asia, particularly India and Pakistan. It is a drought-tolerant plant that thrives in hot climates and poor soils. Growing 2–6 feet tall, it has upright stems, trifoliate leaves, small pale pink to bluish flowers, and slender pods that grow in clusters along the stems. The immature pods can be eaten as a vegetable, while the seeds are processed to produce guar gum, a widely used thickening and stabilizing agent in foods, cosmetics, pharmaceuticals, and industrial products. Because it is a nitrogen-fixing legume, cluster bean is also used as a soil-improving cover crop and livestock forage in dryland farming systems.

Risks & Threats

Cluster bean is generally considered a low-risk species in tropical and subtropical regions when properly managed. As an annual crop that depends on cultivation, it does not typically persist or spread aggressively outside of agricultural settings. However, like many legumes, it produces abundant seeds, so care should be taken to prevent unintended spread in sensitive habitats. Good management practices include harvesting before pods fully mature if volunteers are a concern and monitoring for self-seeded plants near cultivation sites. When grown responsibly, cluster bean can be a useful and sustainable crop for dry climates without posing significant ecological threats.

High Risk Traits:

• Broad soil tolerance: Adaptable to many soil types
  
• Self-compatible: Self-pollinating, sets seed without pollinators
  
• Annual lifecycle: Rapid turnover (1 year)
  
• Intentional dispersal: Widely planted by humans
  
• Pathogen host: Host of potato virus Y
  
• Allergenic: Causes contact dermatitis

Low Risk Traits:

• Domesticated & widely introduced: Cultivated ~1,000 years; repeatedly introduced outside native range for agriculture
  
• Not naturalized: No evidence of naturalization or weediness
  
• Poor unassisted dispersal: No wind, water, or animal dispersal adaptations
  
• No vegetative spread: Reproduces by seed only
  
• Palatable & non-toxic: Used as food and feed
  
• No physical defenses: Lacks spines, thorns, burrs
  
• Herbicide-sensitive: Easily controlled chemically
  
• No fire hazard: Does not promote fire