Phaseolus maculatus
Scheele
Metcalfe Bean
(c) Juan Cruzado Cortés, some rights reserved (CC BY-SA), uploaded by Juan Cruzado Cortés
(c) Bodo Nuñez Oberg, some rights reserved (CC BY-NC), uploaded by Bodo Nuñez Oberg
(c) Radha Veach, some rights reserved (CC BY-NC), uploaded by Radha Veach
What to Eat
Seed - cooked. Toasted. The seedpod is 30 - 74mm long, 10 - 15mm wide, containing variously coloured, spherical seeds 7 - 13mm in diameter. Young seedpods - cooked. The root of subspecies ritensis is reportedly used as a fermenting agent in making an alcoholic beverage called 'batari'. The mature seeds (beans) are edible, but only when thoroughly boiled. As with all wild beans, eating raw or undercooked beans is dangerous and potentially fatal due to the presence of lectins and other anti-nutritive compounds. Boiling neutralizes these toxins and makes the beans safe for consumption. Spotted bean is one of several wild beans native to the Southwest that Native Americans traditionally used. Its beans are nutritious, palatable, and comparable in taste and texture to cultivated beans, with no harsh overtones. Like other wild Phaseolus species, the pods dry and split open at maturity, propelling seeds a short distance—so foragers must time harvests carefully to avoid losing seeds. Nutritional & Foraging Notes: Pods mature from early to mid-autumn. Mature pods are typically brown, brittle, and hairy, while immature pods are green. Beans are relatively easy to gather and winnow. Gathering often involves checking plants repeatedly during the ripening period, since seeds do not all mature at once.
Known Hazards
Where to Find It
Southwestern N. America - Arizona, New Mexico, Texas to southern Mexico
Native to: Arizona, Mexico Central, Mexico Northeast, Mexico Northwest, Mexico Southwest, New Mexico, Texas.
How to Identify
Phaseolus maculatus is a PERENNIAL CLIMBER growing to 4 m (13ft) by 1 m (3ft 3in) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 8 and is frost tender. The flowers are pollinated by Insects. It can fix Nitrogen. It is noted for attracting wildlife. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought.
How to Grow
Phaseolus maculatus is native to semi-arid regions in warm temperate through the subtropical to tropical regions of southwestern N. America. Requires a sunny position in well-drained soil. This species has confusing reports regarding nitrogen fixation. The subspecies maculatus has been shown not to have a symbiotic relationship. However, subspecies ritensis does have this relationship with certain soil bacteria; these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant, but some can also be used by other plants growing nearby. This species occurs in elevations of 1,500–2,500 m asl. USDA Hardiness Zone: 8–11. Weed Potential: Low. This is a native species that grows in desert and foothill habitats, not known to be invasive.
Propagation: Like many species within the family Fabaceae, once they have ripened and dried, the seeds of this species may benefit from scarification before sowing to speed up and improve germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time, they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (careful not to damage the embryo) and soak for 12 hours before sowing.
Medicinal Uses
The fleshy root is used to prepare a purgative. The roots of this species are harvested, dried and cut up for sale as a medicinal product known as Cacolmecac in northern Mexico and Cocolmecac in central Mexico.
Other Uses
This species has confusing reports regarding nitrogen fixation. The subspecies maculatus has been shown not to have a symbiotic relationship. However, subspecies ritensis does have this relationship with certain soil bacteria; these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant, but some can also be used by other plants growing nearby. It is a tertiary wild relative of and potential gene donor to Lima bean (USDA, ARS, GRIN 2017).
Names & Synonyms
Spotted Bean (Phaseolus maculatus Scheele = Phaseolus metcalfei Wooton & Standl.)
