Common Bean

Bush varieties form erect bushes 20–60 centimetres (8–20 inches) tall, while pole, or running, varieties form vines 2–3 metres (7–10 feet) long. All wild members of the species have a climbing habit. All varieties bear alternate, green or purple leaves, which are divided into three oval, smooth-edged leaflets, each 6–15 cm (2–6 in) long and 3–11 cm (1–4 in) wide. The white, pink, or purple flowers are about a centimetre long and have 10 stamens each. The flowers are self-pollinating, which facilitates the selection of stable cultivars. The flowers give way to pods 8–20 cm (3–8 in) long and 1–1.5 cm wide. These may be green, yellow, black, or purple, each containing 4–8 beans. Some varieties develop a string along the pod; these are generally cultivated for dry beans, as green stringy beans are not commercially desirable. The beans are smooth, plump, kidney-shaped, up to 1.5 cm long, range widely in color and are often mottled in two or more colors. The beans maintain their germination capacity for up to five years. Like most Phaseolus species, the genome has 11 chromosomal pairs (2n = 22). The genome is one of the smallest in the legume family at 625 Mbp per haploid genome. Raw or undercooked beans contain a toxic protein called phytohaemagglutinin.

Wild P. vulgaris is native to the Americas. It was domesticated separately in Mesoamerica and in the southern Andes region some 8000years ago, giving the domesticated bean two gene pools. Beans, squash, and maize (corn) are the three Mesoamerican crops that constitute the "Three Sisters", central to indigenous American agriculture. The common bean arrived in Europe as part of the Columbian exchange. It is now grown on every continent except Antarctica.

Like most members of Fabaceae, common beans acquire the nitrogen they require through an association with rhizobia, which are nitrogen-fixing bacteria.

Raw green beans are 90% water, 7% carbohydrates, and 1% protein and contain negligible fat. In a reference amount of 100 grams (3.5 oz), raw green beans supply about 36 calories and are a rich source (20% or more of the US Daily Value, DV) of vitamin K (41% DV) and a moderate source (10–19% DV) of vitamin C, vitamin B6, and manganese. Dry white common beans, after boiling, are 63% water, 25% carbohydrates, and 10% protein and contain little fat. In a reference amount of 100 grams (3.5 oz), boiled white common beans supply about 139 calories and are a rich source of folate and manganese, with moderate amounts of thiamine and several dietary minerals.

Good commercial yield in favorable environments under irrigation is 5 to 7 tonnes per hectare (2 to 3 short ton/acre) fresh and 1.4 to 1.8 t/ha (0.6 to 0.8 short ton/acre) dry seed.

Cultivars and varieties. Archeologists found large-seeded varieties of the domesticated bean in the highlands of Peru, dating to 2300 BC, and spreading to the coastal regions by around 500 BC. Small-seeded varieties were found in sites in Mexico, dating to 300 BC, which then spread north and east of the Mississippi River by 1000 AD. Many well-known bean cultivars and varieties belong to this species, and the list below is in no way exhaustive. Both bush and running (pole) cultivars/varieties exist. The colors and shapes of pods and seeds vary over a wide range.

Production. In 2022, world production of dry common beans was 28 million tonnes, led by India with 23% of the total. Brazil and Myanmar were secondary producers.

Ancient Greeks used the word φάσηλος (phasēlos) to refer to the beans of Asian origins that were cultivated in Europe at the time. The Romans used both the Latinized phaseolus and their own faba to refer to different pre-Columbian species of beans, presumably using the word faseolus for smaller seeds like those belonging to the genus Vigna such as black-eyed peas and the word faba for larger seeds, such as the fava beans. This latter word, faba, was related to the Proto-Germanic bauno, from which the Old English word bean is derived and has the meaning of "bean, pea, legume". When Phaseolus vulgaris arrived in Europe in the 16th century, this species was yet another seed in a pod, thus there were already words in the European languages describing it. In the Americas, P. vulgaris is also known as ayacotl in Nahuatl (Aztec language), búul in Mayan (Maya language) and purutu in Quechua (Inca language). In Argentina, Bolivia, Chile, Paraguay and Uruguay, the Spanish name poroto is used, being derived from its corresponding Quechua word. Additional names include the Castilian Spanish frijol, the Portuguese feijão, and the Catalan fesol.