Many of the varieties grown have been selected to yield a thick, rather fleshy pod in small clusters. These are string or snap beans. In some varieties, chlorophyll is entirely or largely locking in the pods. Such varieties yield wax or butter bean.
Many other varieties are grown primarily for the dried seeds which have a very high food value and keep exceedingly well if dried and protected form insects. Common varieties used as dry beans are pea, yellow eye and red Kidney bean. Shell beans are those in which the nearly but green seed is eaten.
Scarlet Runner Bean, which is related to the garden beans, is often grown as an ornamental plant because of its showy scarlet flowers.
Another species, the Lima bean is widely grown in warmer climates, such as South America. Large flat pods of this plant contain a few large flat seeds.
In Europe a common bean is the Broad Bean. It is also called Windsor or horse bean. Its seeds are rich in nitrogenous compounds and rather hard to digest. These seeds are extensively used for horse food as well as for human consumption.
In the orient the bean crop is entirely Soya bean. The plant is erect bushy annual with trifoliate leaves and bears fruit abundantly.
A large variety of this plant is grown in the orient, where large population depends on it as a major source for protein. In the united states it is cultivated for various reasons such as it grows well on poor soils, and being a legume, with its characteristic associated nitrogen fixing bacteria, it can build up the fertility of the soil.
Its seeds are rich in oil. Its is now used in the preparation of enamels, linoleum, inks, paints, soaps etc. its oil is further used as a source of industrial proteins for the production of adhesives, sizing, coatings for paper and other products. In Africa particular species of Soya bean is used as food.
All the plants mentioned so far are legume, having bean-like fruit. But one variety, the vanilla bans is different. They are the fruits of a climbing orchid growing wild in central America and Mexico. Since prehistoric times these fruits have been used to flavour chocolate.
Many other plants contain Vanillin and so they are used in the manufacture of artificial vanilla. Among these are a tropical South American bean plant, the seeds of which are called Tonka beans.
