Phaseolus acutifolius - A.Gray

Common Name

Tepary Bean

Family

Fabaceae

USDA hardiness

8-11

Known Hazards

The seed contains various antinutritional factors, such as trypsin inhibitors, flatulent oligosaccharides and phytic acid[299 ]. The lectin activity is exceptionally high, but is readily reduced by cooking; whereas cyanogenic glucosides have not been detected[299 ]. Consumption of raw tepary bean flour has been recorded to cause death in mice and rats within 3 - 4 days, but soaking and cooking the seeds eliminated toxicity completely[299 ].

Habitats

Usually found growing along stream beds and dry washes in pine-oak forests, scattered among small bushes and cacti[1555 ].

Range

Central America - Guatemala; Southwest N. America - southern Mexico north to Arizona, New Mexico, and Texas.

Edibility Rating

(3 of 5)

Other Uses

(2 of 5)

Weed Potential

Medicinal Rating

(2 of 5)

Care (info)




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Summary

Phaseolus acutifolius is a herbaceous, annual plant growing from a fibrous rootstock. It produces weak stems that either trail over the ground or twine around other plants for support[418 ]. The plants vary widely in height according to cultivar, with dwarf forms only 30cm tall and large forms up to 4 metres tall[299 , 418 , 1555 ]. The plant is grown mainly for its edible seed and is said to have been in cultivation for over 5,000 years in southwestern N. America[375 ]. Nowadays it is grown mainly in south-western USA and Mexico as a traditional pulse crop, though it is also cultivated, mostly on a small scale, in further parts of USA; Central America; the West Indies; Chile; Australia; S Asia; E and W Africa (Uganda, Mali, Senegal)[317 ]. After World War II the cultivation decreased drastically in the traditional areas, the crop however is nowadays once more gaining interest[317 ]. The cultivated forms were formerly called var latifolius. This was recently recognised as an obsolete synonym of var acutifolius (formerly considered a wild form of the species). This means this variety comprises wild and cultivated populations[317 ].

Physical Characteristics

Phaseolus acutifolius is a ANNUAL CLIMBER growing to 2 m (6ft) by 1 m (3ft 3in) at a fast rate.
See above for USDA hardiness. It is hardy to UK zone 7 and is not 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.

UK Hardiness Map US Hardiness Map

Synonyms

Phaseolus acutifolius latifolius G.F.Freeman. Phaseolus montanus Brandegee. Phaseolus pauper Standl. Phaseolus tenuifolius (A.Gray) Wooton & Standl. Common Name: Tepary Bean.

Plant Habitats

Edible Uses

Mature seeds - dried[310 , 418 ]. They are used as dry shell beans to make soups[310 , 418 ]. They are also ground into flour, fried, parched, or processed into a meal for commercial use[418 ]. Tepary beans have a strong flavour and odour and are less palatable than common beans[299 ]. The seedpods are 40 - 100mm long, 5 - 13mm wide and 4 - 8mm thick, containing 2 - 9 oblong to rounded seeds 4 - 10mm long, 4 - 7mm wide and 2 - 5mm thick[418 , 1555 ]. On storage, the dry seeds become very hard and take a very long time to cook[310 ]. Cultivars with white seeds have a more permeable seedcoat than cultivars with black seeds, resulting in a shorter cooking time[299 ]. The young, green seedpods are occasionally eaten[299 ]. The seeds can be sprouted and then eaten cooked or in salads[299 ]. The leaves are considered edible in parts of Africa, but they are tougher than those of common bean (Phaseolus vulgaris) and take longer to cook[299 ]. The wideleaf tepary bean (Phaseolus acutifolius var. latifolius) produces mature seeds that are edible once properly prepared. Like other members of the bean family, the raw or undercooked seeds are toxic due to the presence of lectins and other anti-nutritive compounds. These substances can cause serious health effects, but fortunately, they are destroyed by thorough boiling. Cooking also reduces additional compounds such as trypsin inhibitors and phytates, leaving the beans safe to eat. Sprouts from wild beans should not be eaten raw, as they may retain harmful levels of these compounds. When boiled, wideleaf tepary beans are comparable in flavor, texture, and aroma to cultivated beans. They were traditionally eaten by Native American peoples in the southwestern United States, and their domestication can be traced back more than 2,000 years to the Tehuacan Valley of Mexico[2-3]. Tepary beans are highly drought-tolerant and well adapted to desert conditions, capable of producing a crop in as little as two months during the hot summer following seasonal rains. The beans are generally harvested in early to mid-autumn. Immature pods are dull green, while mature pods turn brown, brittle, and often hairy. When ripe, they split open and scatter the seeds, sometimes during collection, so careful handling is needed. Because the pods ripen over several weeks, frequent checking ensures a good harvest. Even after pods have opened, beans can often be gathered from the ground for some time, though they can be difficult to spot. Once collected, the beans require little processing, as winnowing is straightforward, and they make a reliable and nutritious food source [2-3].

References More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.

None known

References More on Medicinal Uses

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Other Uses

Agroforestry Uses: Tepary bean has occasionally been grown as a green manure, e.g. in the United States[299 ]. It may also be used as a cover crop and an intercrop in agroforestry systems[299 ]. Other Uses: The plant is bitten and held between the teeth as a traditional treatment for toothache[257 ].

Special Uses

References More on Other Uses

Cultivation details

Phaseolus acutifolius is a plant mainly of the drier subtropics. However, it can also be cultivated in warmer regions of the temperate zone so long as there is a sufficiently long growing season to ripen the crops in autumn. It can also be grown in tropical areas at elevations up to 1,900 metres so long as the climate is not excessively wet[418 ]. It prefers a mean annual temperature within the range 20 - 30°c, but can tolerate 8 - 38°c[418 ] It cannot be grown in areas where night temperatures fall below 8°c[418 ]. It prefers a mean annual rainfall of 600 - 1,000mm, tolerating 300 - 1,700mm[418 ]. Excessive rainfall may create vegetative growth at the expense of seed yield[418 ]. The plant can withstand heat and a dry atmosphere, though only very few varieties are suited for the wet tropics[418 ]. Requires a sunny position[418 ]. Succeeds in most soils that are well-drained[418 ]. Succeeds in poor, shallow soils[310 ]. Established plants are rather drought resistant[317 ].Prefers a pH in the range 6 - 7, but tolerates 5 - 8[418 ]. The crop can be grown on residual soil moisture[418 ]. Often cultivated for its edible seed, there are many cultivated forms with seeds considerably larger than the wild forms[1555 ] The seedpods of wild forms have pods that burst open explosively when ripe to expel the seeds, which are smaller than cultivated forms[1556 ]. The seedpods of cultivated forms remain closed when the seeds first ripen, making harvesting much simpler[1556 ]. The species is highly daylength sensitive, growmg under natural field conditions during the long days of summer and beginning to bloom in late summer when daylength has fallen to around 13 hours[1555 ]. Flowering occurs within 27 - 40 days from germination[299 ]. First harvest may be taken in as little as 60 days in the tropics, though in cooler climates it can be up to 120 days from sowing[418 ]. The seeds of many domesticated types of tepary bean are shattered less easily than those of wild types[299 ]. Average yields of dry seed under dry conditions are reported to be 450 - 800 kg/ha and with irrigation 0.9-1.7 t/ha[418 ]. In areas of poor rainfall, tepary bean has possibilities as a catch-crop where a rapid food supply is needed[310 ]. This species has a symbiotic 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[755 ]. Tepary beans are highly drought-tolerant and well adapted to desert conditions, capable of producing a crop in as little as two months during the hot summer following seasonal rains [2-3].

References Carbon Farming Information and Carbon Sequestration Information

Temperature Converter

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Plant Propagation

The seed of cultivated forms absorbs water easily; in moist soils, the testa wrinkles within 5 minutes, whilst when soaked in water, the testa wrinkles in 3 minutes[299 ]. This leads to quick and even germination[299 ]. The rate of germination increases with increasing temperatures from 10 - 35°c[299 ]. Seedling emergence is faster in white-seeded than in dark-seeded types[299 ]. The seed of wild forms usually has a hard seedcoat and will benefit from scarification before sowing in order 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 (being careful not to damage the embryo) and soak for a further 12 hours before sowing. The seeds of domesticated types have no dormancy, which is a disadvantage in humid regions, where fallen seeds will germinate rapidly[299 ].

Other Names

If available other names are mentioned here

Wideleaf tepary bean

Native Range

Native to: Arizona, Mexico Northeast, Mexico Northwest, Mexico Southwest, New Mexico, Texas. Introduced into: Canary Is., Central European Rus, India, Kazakhstan, Kirgizstan, Krym, Mali, South European Russi, Ukraine.

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it's worth checking.

Tepary beans are not generally considered a weedy or invasive species. It is native to the arid and semi-arid regions of the southwestern United States and Mexico, where it has coexisted with natural ecosystems for thousands of years.

Conservation Status

IUCN Red List of Threatened Plants Status : Not available

Related Plants

Latin Name	Common Name	Habit	Height	Hardiness	Growth	Soil	Shade	Moisture	Edible	Medicinal	Other
Phaseolus acutifolius var. acutifolius	Sharpleaf Tepary Bean	Annual Climber	2.0	6-11	F	LMH	N	DM	3	2	2
Phaseolus coccineus	Runner Bean, Scarlet runner	Annual/Perennial	3.0	1-12	F	LMH	N	M	4	0	3
Phaseolus filiformis	Frijolillo	Annual Climber	2.0	7-10		LMH	N	DM	2	0	2
Phaseolus lunatus	Lima Bean, Sieva bean	Perennial Climber	6.0	10-12		LMH	N	M	4	1	3
Phaseolus maculatus	Metcalfe Bean	Perennial Climber	4.0	8-11	F	LMH	N	DM	3	2	2
Phaseolus polystachios	Thicket Bean. Wild bean	Climber	3.0	6-10	F	LMH	SN	M	2	0	3
Phaseolus vulgaris	French Bean, Kidney bean	Annual	2.0	2-11		LMH	N	M	5	2	2

Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.

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Author

A.Gray

Botanical References

Links / References

For a list of references used on this page please go here
A special thanks to Ken Fern for some of the information used on this page.