Ginkgo

Phylum Ginkgophyta

Ginkgo biloba, the maidenhair tree, is the only surviving member of the Ginkgolaes. It is a gymnosperm with distinct fan-shaped leaves, which resemble the leaflets of the maidenhair fern. Ginkgo is native to China, but populated temperate zones in the eastern and western hemispheres during the dinosaur age. Competition with flowering plants reduced their range to Asia, and their horticultural use by Buddhists is touted as saving the group from extinction. Unlike many gymnosperms, Ginkgo is a deciduous tree, with seeds that are pulpy. The tree appears to be resistant to most pests and pollution, and therefore frequently used as urban street trees.

Above: Ginkgo biloba tree

Above: the bi-lobed leaf of Ginkgo biloba, usually found on long shoots

Ecology & Form

  • It is assumed that there are no wild populations of Ginkgo, although Tang et al. (2012) has presented evidence of wild Ginkgo in the Dalou Mountains of China

    • These wild populations seem to prefer rock crevices as habitats

  • Conifer-like architecture and form; Ginkgo becomes more angiosperm-like in silhouette with age

Sporophyte (=seed-bearing phase)

Vegetative features

Stems

Leaves

    • Fan-shaped leaves, although shape is highly-variable

    • Leaves are deciduous

    • Dichotomous branching veins

Reproductive Structures

  • Ginkgo biloba is dioecious; separate male and female plants

  • Pollen produced in loose cones (=microstrobili) on short shoots

  • Paired ovules born on stalks on short shoots; Ginkgo biloba does not have female cones (megastrobili), but extinct species did have females cones

  • Ovule has a three-layered integument

    1. Fleshy outer layer (sarcotesta): this layer emits butyric acid which gives the seeds a strong, disagreeable odor

    2. Stony inner layer (sclerotesta): This is a pit-like layer

    3. Thin endotesta

  • Ginkgo does not produce fruit! It is a gymnosperm.

  • Dispersal: Researchers have reported a number of Asian members of Carnivora feeding on, and presumably dispersing the nutrient-rich seeds. which suggests that the rancid-smelling sarcotesta may be attracting primarily nocturnal scavengers by mimicking the smell of rotting flesh—in essence acting as a carrion-mimic (Del Tredici et al. 1992; Del Tredici 2008 Arnoldia)

Gametophyte (=gamete-bearing phase)

  • Male gametophyte, found inside the pollen, produces flagellated sperm (sperm swim to egg)

  • Female gametophyte produces a few archegonia

Above: ovules of Ginkgo

Above: pulpy seeds of Ginkgo

Above: pollen cones of Ginkgo

Diversity

  • Only one species remains, Ginkgo biloba

Geologic Age

Classification

└Embryophytes

└Tracheophytes

└Euphyllophytes

└Lignophytes

└Spermatophytes

└Ginkgoales

Above: pulpy seeds of Ginkgo, sometimes called "silver apricots"

Above: autumn color of Ginkgo

Above: Various features of the Ginkgoales, living and extinct

Above: Wild populations of Ginkgo biloba in the Dalou Mountains for Southwestern China (from Fig 3, Tang et al. 2012)

Additional Resources