Ginkgophytes

Ralph E. Taggart, Professor

Department of Plant Biology

Department of Geological Sciences

Michigan State University


Ginkgo biloba, shown here, is the last surviving member of a lineage that originated in the late Paleozoic and became quite diverse during the Mesozoic. The living plant has distinctive, fan-shaped leaves, produced in clusters at the ends of short, lateral shoots, and it is very easy to recognize. Although probably extinct in the wild, the plant was domesticated thousands of years ago in China. The tree is wisely planted throughout temperate regions of the world and is particularly resistant to disease, insect predation and air pollution. For these reasons, it is commonly used as a street tree and there are numerous examples on the campus, including many young trees recently planted at the northern end of Farm Lane.

Female trees (the sexes are separate) produce what looks like a berry, but it is actually a false fruit. The ovules are produced in pairs, unprotected, on the ends of elongate stalks. Pollination is via the wind and, as the ovule develops, a ring of tissue at its base begins to divide, producing a fleshy tissue that eventually encloses the developing seed. When these fall to the ground and decay, they produce a strong odor as a result of the presence of butyric acid. For this reason, landscape architects prefer to use male trees for decorative plantings.


Paleozoic Ginkgophytes

Dichophyllum, an early ginkgophyte from the late Carboniferous of Kansas (Annals of the Missouri Botanical Garden). While the leaves of extant ginkgoes are weakly two-lobed, early ginkgophyte leaves had multiple lobes as shown here.


Mesozoic Ginkgophytes

Ginkgo digitata leaf from the late Cretaceous of Alaska (Andrews, 1947). The ginkgophyte complex became highly diverse and widely distributed in the Mesozoic. This specimen looks quite similar to the modern G. biloba, except that the leaves are four-lobed, a characteristic commonly observed in very young seedlings of the living species.

During the Cenozoic, the group became progressively more restricted in distribution. The last known fossil occurrence in North America was in the mid-Miocene (~15 Ma) in the Succor Creek region of eastern Oregon and western Idaho.


Ralph E. Taggart (taggart@msu.edu)