| Classification |
| Kingdom: Plantae
Division: Ginkgophyta
Class: Ginkgoopsida
Order Type: Gymnosperm
Order: Ginkgoales
Family: Ginkgoaceae
Family Common Name: Ginkgo Family
Genus: Ginkgo |
Defining Features: Phylum
of seed plants represented by one living species, Ginkgo
biloba. The group was well represented during the Mesozoic with worldwide
distribution. This deciduous tree bearing distinctive fan-shaped leaves.
Branches have numerous spur shoots that bear distinctive fan-shaped leaves
and the reproductive structures. Stem has extensive secondary growth producing
considerable secondary xylem.
Defining Morphology: Reproductive
Characteristics: Dioecious trees. Megasporangiate trees bearing two ovules
at the end of a stalk. Typically only one ovule develops into a mature
seed. Integument includes three layers. The inner layer develops into the
stony seed coat. The outer two develop into a fleshy fruit-like tissue.
Because this tissue has a strong, unpleasant odor, "male" buds
are typically grafted onto seedling roots to produce "male" trees
for ornamental use. Microsporangiate ("male") trees bear catkin-like
microsporangiate strobili. These release pollens (microgametophytes) that
are wind borne. Pollen produces a pollen tube that is haustorial and which
delivers flagellated sperm to an egg in an archegonium of the female gametophyte.
Pollen is borne in axillary spike-like clusters of stamen-like sporangiophires;
pollen sacs 2 per sporangiophore, reflexed. Ovules are 2 to 3 or more,
naked, borne at ends of forking peduncle; seeds large, drupe-like with
foul-scented fleshy outer layer. Vegetative Features: Habit as trees. Leaves
alternate and fan-shaped.
Distribution: This species
is restricted to China where it may be extinct in the wild.
Economic Use: Widely planted
as an ornamental. It is especially useful as a street tree as it is tolerant
of city polluted air.
Number of Genera Globally:
1
Number of Species Globally:
1
