Phaseolus vulgaris (Green beans, Large white beans, Flageolet, Black bean,
Borlotto bean, Red kidney bean, Cannellino bean, Sugar bean) Life
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Eurosid I > Fabales > Family: Fabaceae > Subfamily: Papilionoideae
> Genus: Phaseolus
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Phaseolus vulgaris, Grahamstown, Eastern
Cape, South Africa. [photo
H.G.
Robertson, Iziko ©] |
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Kidney beans. [photo
H.G.
Robertson, Iziko ©] |
Phaseolus vulgaris Grahamstown, Eastern
Cape, South Africa. [photo
H.G.
Robertson, Iziko ©] |
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Sugar beans. [photo
H.G.
Robertson, Iziko ©] |
Haricot beans. [photo
H.G.
Robertson, Iziko ©] |
Originate from Central and South America. The earliest archaeological evidence of domesticated
bean seeds is from 7500 years ago at a site in mountainous northern Peru.
Phaseolus vulgaris originates from South and
Central America where its wild forms
are found over a wide discontinuous range from Argentina to Mexico. There
are morphological and biochemical differences between the populations in Mexico
and those in South America and in fact hybrids between plants from the two
regions are largely sterile. This sort of evidence is good enough to place them
in different species but this has not been done because they both gave rise
either separately or in combination to the various cultivars of beans now placed
in Phaseolus vulgaris. Analysis of seed proteins, isozymes and
differences in morphology of P. vulgaris cultivars show that this species
has six major races that are the result of six separate domestication events
between Mexico and the southern Andes. There has been some subsequent
hybridisation between these races to produce further varieties. Therefore to
split up Phaseolus vulgaris cultivars between the two wild species is
likely to lead to a confusing nomenclature but perhaps this is not a good enough
reason for not doing so..
Domesticated bean seeds can be distinguished from those of wild plants
because they are larger. The earliest archaeological evidence of domesticated
bean seeds is from 5500 BC at a site in mountainous northern Peru. At this time there was no
domesticated maize and no pottery making. The earliest evidence of bean seeds from
archaeological sites in Mexico is from 5000 BC. So by this time beans had been
independently domesticated in the two regions. Despite these early beginnings,
domesticated beans took a long time to spread more widely through North and
South America and to be grown as a staple crop. However, by the 1400's beans had
caught up with maize and become a staple crop through most of the
Americas. By the mid-1500's, cultivars of P. vulgaris were being
grown in Europe. Beans were introduced into Africa probably by the
Portuguese and spread into the interior faster than European exploration.
The pods of green beans are cooked as a vegetable. Other
varieties yield beans that are often stored dry and then rehydrated and cooked
as vegetables. Raw beans contain protease inhibitors and lectins which can
interfere with digestion. The lectins prevent absorption of nutrients in the
intestine. However, these are destroyed by cooking.
Ecological interactions
Not covered here other than to mention
Phakopsora pachyrhizi (Asian soybean rust), which infects about 95
species of legume including Phaseolus vulgaris.
References
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Sauer, J.D. 1993. Historical geography of
crop plants - a select roster. CRC Press, Boca Raton, Florida.
Text by Hamish G. Robertson |