description
Ginkgos are large trees in the Ginkgoaceae family, normally reaching a
height of 20–35 m (66–115 feet), with some specimens in China being over 50
m (164 feet).
The tree has an angular crown and long, somewhat erratic
branches, and is usually deep rooted and resistant to wind and snow damage.
Young trees are often tall and slender, and sparsely branched; the crown
becomes broader as the tree ages. During autumn, the leaves turn a bright
yellow, then fall, sometimes within a short space of time (one to 15 days).
Ginkgo branches grow in
length by growth of shoots with regularly spaced leaves, as seen on most
trees. From the axils of these leaves, "spur shoots" (also known as short
shoots) develop on second-year growth. Short shoots have very short
internodes (so they may grow only one or two centimeters in several years)
and their leaves are usually not lobed. They are short and knobby, and are
arranged regularly on the branches except on first-year growth. Because of
the short internodes, leaves appear to be clustered at the tips of short
shoots, and reproductive structures are formed only on them.
The leaves are
unique among seed plants, being fan-shaped with veins radiating out into the
leaf blade, sometimes bifurcating (splitting) to form a network. Two veins
enter the leaf blade at the base and fork repeatedly in two; this is known
as dichotomous venation.
Ginkgos are dioecious, with separate sexes, some
trees being female and others being male. Male plants produce small pollen
cones with sporophylls, each bearing two microsporangia spirally arranged
around a central axis. Female plants do not produce cones. Two ovules are
formed at the end of a stalk, and after pollination, one or both develop
into seeds.
A combination of resistance to disease, insect-resistant wood and the
ability to form aerial roots and sprouts makes
ginkgos long-lived, with some
specimens claimed to be more than 2,500 years old.
common names & nomenclature
The common name maidenhair tree is because the leaves resemble the pinnae
of the maidenhair fern, Adiantum capillus-veneris. The specific epithet
biloba derived from the Latin bis, 'two' and loba, 'lobed', referring to the
shape of the leaves.
Also known as:
bal guo, maidenhair tree
