Ginkgo biloba

Leaf and seed extracts from this tree have been used in traditional herbal medicines for centuries and continue to be sold as foods and supplements. Trees in China, France, and South Carolina are major producers of Ginkgo leaves—about 8,000 tons per year commercially.

 Members of this species reach sexual maturity at 20-30 years of age. While many tree species are bisexual, this one is not. It is dioecious, meaning male and female reproductive structures exist on separate trees. 

Ginkgoes do not produce flowers or true fruits because they are a member of an ancient lineage that diverged before the evolution of these structures. Male trees have pollen-producing cones, and the pollen contains motile swimming sperm. Female trees produce ovules that develop into seeds after they are fertilized by sperm. For mature trees, sexual reproduction occurs in the spring (~April) via wind pollination. 

After fertilization, seeds, which are sometimes called “nuts,” mature on the tree. Nuts drop from female trees approximately one month after fertilization, usually between August and September.

 Squirrels can disperse the mature nuts that fall, but many animals avoid them, likely because of a fleshy covering (sarcotesta), that contains butyric acid. This compound is also found in rancid butter, so the nuts can smell putrid as they decompose on the ground.

 Usually, male trees are cultivated to avoid the smell and mess of the fleshy nuts, but pollen from male trees can trigger allergies in some people.

*Dr. Sara Wright produced this resource for her Plant Diversity course in the Department of Biological & Biomedical Sciences.