Taxonomic notes: Phaseolus costaricensis Freytag & Debouck is a secondary wild relative of common bean, P. vulgaris L. var. vulgaris, scarlet runner bean, P. coccineus L. and year bean, P. dumosus Macfad. (USDA, ARS, National Genetic Resources Program 2015).

Phaseoulus costaricensis is native to Costa Rica and Panama (USDA, ARS, National Genetic Resources Program 2015). Based on occurrence data provided by Crop Wild Relatives and Climate Change (2013), its extent of occurrence (EOO) is less than 12,000 km².

This large 3–8 m long vine climbs and sprawls over shrubs and trees in sunny openings of humid montane forests characterized by Alnus and Erythrina, with bamboo and numerous epiphytes (ferns, orchids, aralis and bromeliads), and is often found in disturbed (cut or burnt) areas, in coffee plantations or in pastures (Freytag and Debouck 2002). The plants are most frequent and abundant on steep slopes in inaccessible areas at 1,400–2,100 m (most often at 1,600–1,800 m) and are often found growing in very moist rocky areas, often near streams or riversides, in dark brown soils with high organic content, derived from lava or volcanic ash or metamorphic schists (Freytag and Debouck 2002).

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It is a secondary wild relative of, and potential gene donor to common bean, scarlet runner bean and year bean (USDA, ARS, National Genetic Resources Program 2015). It has previously been used to confer traits for disease resistance to common bean, including angular leaf spot, ascochyta blight, bean green mosaic virus, bean yellow mosaic virus, root rots and white moulds, as well as resistance to cold (Singh 2001).

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Phaseolus costaricensis has an extent of occurrence (EOO) of less than 20,000 km² but the species inhabits inaccessible areas which are unlikely to be affected by human interference and it is also often found in disturbed areas, coffee plantations and pastures. It is therefore assessed as Least Concern.

• Crop Wild Relatives and Climate Change. 2013. Crop Wild Relative Global Occurrence Database. Available at: http://www.cwrdiversity.org/checklist/cwr-occurrences.php.
• Freytag, G.F. and Debouck, D.G. 2002. Taxonomy, Distribution, and Ecology of the Genus Phaseolus (Leguminosae–Papilionoideae) in North America, Mexico and Central America. Botanical Research Institute of Texas, Fort Worth.
• Singh, S. 2001. Broadening the genetic base of common bean cultivars. Crop Science 41: 1659-1675.
• USDA, ARS, National Genetic Resources Program. 2015. Germplasm Resources Information Network - (GRIN) [Online Database]. National Germplasm Resources Laboratory, Beltsville, Maryland. Available at: http://www.ars-grin.gov/.