Vicia faba

Vicia faba, commonly known as the broad bean, fava bean, or faba bean, is a species of vetch, a flowering plant in the pea and bean family Fabaceae. It is widely cultivated as a crop for human consumption, and also as a cover crop. Varieties with smaller, harder seeds that are fed to horses or other animals are called field bean, tic bean or tick bean. This legume is commonly consumed in many national and regional cuisines.

Some people suffer from favism, a hemolytic response to the consumption of broad beans, a condition linked to a metabolic disorder known as G6PDD. Otherwise the beans, with the outer seed coat removed, can be eaten raw or cooked. With young seed pods, the outer seed coat can be eaten, and in very young pods, the entire seed pod can be eaten.

Vicia faba is a stiffly erect, annual plant 0.5 to 1.8 metres (1+1⁄2 to 6 ft) tall, with two to four stems that are square in cross-section. The leaves are 10 to 25 centimetres (4 to 10 in) long, pinnate with 2–7 leaflets, and glaucous (grey-green). Unlike most other vetches, the leaves do not have tendrils for climbing over other vegetation.

The flowers are 1 to 2.5 cm (1⁄2 to 1 in) long with five petals; the standard petals are white, the wing petals are white with a black spot (true black, not deep purple or blue as is the case in many "black" markings) and the keel petals are white. Crimson-flowered broad beans also exist, which were recently saved from extinction. The flowers have a strong sweet scent which is attractive to bees and other pollinators.

The fruit is a broad, leathery pod that is green, but matures to a dark blackish-brown, with a densely downy surface; the wild species has pods that are 5 to 10 cm (2 to 4 in) long and 1 cm diameter, but many modern cultivars developed for food use have pods 15 to 25 cm (6 to 10 in) long and 2–3 cm thick. Each bean pod contains 3–8 seeds. They are round to oval and have a 5–10 mm diameter in the wild plant, but are usually flattened and up to 20–25 mm long, 15 mm broad and 5–10 mm thick in food cultivars. V. faba has a diploid (2n) chromosome number of 12 (six homologous pairs). Five pairs are acrocentric chromosomes and one pair is metacentric.

The diploid genome of Vicia faba contains 13 GB of DNA, mostly obtained through amplification of retrotransposons and satellite repeats. The genome is one of the largest diploid field crops and contains a predicted 34,221 protein-coding genes.

Broad beans have a long tradition of cultivation in Old World agriculture, being among the most ancient plants in cultivation and also among the easiest to grow. While their wild ancestor has not been identified and their origin is unknown, charred legumes of a possible wild-type progenitor have been identified at the Natufian site of the el-Wad Terrace. Carbonised domestic faba bean remains were discovered at three adjacent Neolithic sites in Israel's Lower Galilee (Yiftah'el, Ahi'hud and Nahal Zippori). Based on the radiocarbon dating of these remains, scientists now believe that the domestication of the crop may have begun as early as 8,250 BCE.

Broad beans are still often grown as a cover crop to prevent erosion because they can overwinter and, as a legume, they fix nitrogen in the soil. The broad bean has high plant hardiness; it can withstand harsh and cold climates. Unlike most legumes, the broad bean can be grown in soils with high salinity, as well as in clay soil. However, it prefers rich loams.