Ginkgo

Ginkgo (Ginkgo biloba) is a gymnosperms plant, which appeared during the Jurassic period (dating back 270 million years). During this age Ginkgo was widespread at land and even after many other species disappeared, this plant has remained unchanged up to the present day.

Today Ginkgo is the only existing species in division Ginkgophyta. For centuries it was believed that the species was extinct in the wild, but it was found in the forests of East China. Ginkgo specimens were brought to Europe in the 18th century and by the end of the 19th century the species was introduced to Bulgarian gardens and parks. In Bulgaria Ginkgo can be seen relatively rarely as parks or decorative tree.

Ginkgo is a medium sized deciduous tree, up to 20-35 m high as individual specimens in China have reached more than 50 m. It often occurs with acute crown and long disordered branches. The roots are deep and the tree is resistant to wind and snow. This tree grows a large number of shoots with regularly spaced leaves. The fan-shaped leaves are elongated along the branches. The leaves are unique among seed plants, being fan-shaped with veins radiating out into the leaf blade, sometimes bifurcating (splitting), but never anastomosing to form a network. Two veins enter the leaf blade at the base and fork repeatedly in two; this is known as dichotomous venation. In autumn the leaves turn bright yellow, then fall off fast sometimes only for 1 to 15 days.

In 1771 the Swedish botanist Carl Linnaeus named the tree Ginkgo biloba. The name "ginkgo" is the phonetic pronunciation of the Japanese word for this type of tree, and "biloba", ie "Binary" refers to the characteristic fan-like-shape of the leaves.

Ginkgo is a dioecious plant, which means that an individual has the reproductive organs of one sex only, so that it can be either female or male. Male trees produce small green pollen cones with sporophylls that spread pollen. Female produce ovules. Two ovules are formed at the end of a stalk. Ginkgos are pollinated by the wind in late autumn. After pollination they develop seeds resembling small silver-yellow-orange plums or apricots. Hence the name of the tree "silver apricot", which in Japanese is pronounced as "ginkyo". These bead-like seeds are 1.5 to 2 cm in size. They are composed of three layers: soft fleshy husk (when the seed is ripe it ferments and odors a specific smell), solid part (a shell like pistachios) and a core (consisting of embryo surrounded by nutrient tissue).

The combination of resistance to diseases and insects unyielding trunk bark makes the ginkgo one of the long living trees.

Ginkgo trees can be found on up to 1500 m altitude.
Ginkgo biloba is included in the Red List of globally threatened species of the International Union for Conservation of Nature (IUCN) categorized as "endangered".

Bojana Ribarova