A Banyan (also Banian) is a fig that starts its life as an
epiphyte (a plant growing on another plant) when its seeds
germinate in the cracks and crevices on a host tree (or on
structures like buildings and bridges). "Banyan" often
refers specifically to the Indian banyan or Ficus
benghalensis, which is the national tree of the Republic of
India, though the term has been generalized to include all
figs that share a characteristic life cycle, and
systematically to refer to the subgenus Urostigma.
Picture - Banyan with
characteristic adventitious prop roots. |
Like other fig species (including the common edible fig
Ficus carica), banyans bear multiple fruit in structures
called syncarps. The Ficus syncarp supplies shelter and food
for fig wasps and in turn, the trees are dependent on the
fig wasps for pollination.
The seeds of banyans are dispersed by fruit-eating birds.
The seeds are small, and most banyans grow in forests, so
that a plant germinating from a seed that lands on the
ground is unlikely to survive. However, many seeds land on
branches and stems of trees or on buildings. When those
seeds germinate they send roots down towards the ground, and
may envelop part of the host tree or building structure,
giving banyans the casual name of "strangler fig". The
"strangling" growth habit is found in a number of tropical
forest species, particularly of the genus Ficus, that
compete for light. Any Ficus species showing this habit may
be termed a strangler fig.
The leaves of the banyan tree are large, leathery, glossy
green and elliptical in shape. Like most fig-trees, the leaf
bud is covered by two large scales. As the leaf develops the
scales fall. Young leaves have an attractive reddish tinge.
Older banyan trees are characterized by their aerial prop
roots that grow into thick woody trunks which, with age, can
become indistinguishable from the main trunk. Old trees can
spread out laterally, using these prop roots to cover a wide
area. In some species the effect is for the props to develop
into a sort of forest covering a considerable area, every
trunk connected directly or indirectly to the central trunk.
The topology of this structure of interconnection inspired
the name of the hierarchical computer network operating
system Banyan VINES.
In a banyan that envelops a support tree the mesh of roots
growing round the support tree eventually applies very
considerable pressure and commonly kills the tree. Such an
enveloped dead tree eventually rots away so that the banyan
becomes a "columnar tree" with a hollow central core. In
jungles such hollows are particularly desirable shelters to
many animals. |
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Banyan Trees