What is Banyan?

Legal Definition
A banyan, also spelled "banian", is a fig that begins its life as an epiphyte, i. e. a plant that grows on another plant, when its seed germinates in a crack or crevice of a host tree or human edifice. "Banyan" often specifically denominates Ficus benghalensis (the "Indian banyan"), which is the national tree of the Republic of India, though the name also has been generalized to denominate all figs that share a common life cycle and used systematically in taxonomy to denominate the subgenus Urostigma.

Like other fig species, including the common edible fig Ficus carica, banyans bear multiple fruit in structures denominated "syncarps. The syncarp of Ficus species supplies shelter and food for fig wasps and, in turn, the trees are totally dependent on the fig wasps for pollination.

Frugivore birds disperse the seeds of banyans. The seeds are small, and because most banyans grow in woodlands, a seedling that germinates on the ground is unlikely to survive. However, many seeds fall on the branches and stems of other trees or on human edifices, and when they germinate they grow roots down toward the ground and consequently may envelop part of the host tree or edifice. For this reason banyans bear the colloquial name "strangler fig". A number of tropical banyan species that compete for sunlight, especially of the genus Ficus, exhibit this strangling habit.

The leaves of the banyan tree are large, leathery, glossy, green, and elliptical. Like most figs, the leaf bud is covered by two large scales. As the leaf develops the scales abscise. Young leaves have an attractive reddish tinge.

Older banyan trees are characterized by aerial prop roots that mature into thick, woody trunks, which can become indistinguishable from the primary trunk with age. Old trees can spread laterally by using these prop roots to grow over a wide area. In some species, the prop roots develop over a considerable area that resembles a grove of trees, with every trunk connected directly or indirectly to the primary trunk. The topology of this massive root system inspired the name of the hierarchical computer network operating system "Banyan VINES".

In a banyan that envelops its host tree, the mesh of roots growing around the latter eventually applies considerable pressure to and commonly kills it. Such an enveloped, dead tree eventually decomposes, so that the banyan becomes a "columnar tree" with a hollow, central core. In jungles, such hollows are very desirable shelters to many animals.
-- Wikipedia
Legal Definition
In East Indian law. A Hindoo merchant or shop-keeper. The word is used in Bengal to denote the native who manages the money concerns of a European, and sometimes serves him as an interpreter.
-- Black's Law Dictionary