Ginkgo tree (Maidenhair) – a quick guide w/ photos.


about 9 green ear shaped leaves of gingko hanging from the tree

In this article, with the help of photos, we will learn about the Ginkgo biloba tree. The tree is sometimes simply referred to as ginkgo or maidenhair.

Although ginkgos are not commonly implicated in allergies, we will still learn how and when their pollen spreads. Why? Because, it is a wind-pollinated plant and if you have a tree in the neighborhood, you are certain to get some exposure. And while ginkgos are not currently recognized as an allergen, I would still like to make this information available, just in case.

Tree facts and figures

Ginkgo tree profileGinkgo biloba
Pollen seasonSpring
Pollination typeWind-transported; releases abundant pollen in the air
GenderDioecious: Male and female trees are separate. Most of the city trees in the US are male.
Cross-reactivities with other pollenNot known.
Pollen source1 to 2 inches long green catkins.
Tree leavesfan-shaped (or elephant’s ears shaped), green during summer, bright yellow during autumn.
Tree shape and sizeThe city trees are generally around 25-30 feet tall and have a spreading canopy.
Several green fan-like leaves of ginkgo and a couple of one inch long catkins hanging on a tree branch
Ginkgo in early spring bloom.

How to know if a ginkgo tree is releasing pollen?

Only the male ginkgo trees release pollen. As a matter of fact, most of the city trees are male in the US. The female trees are not planted knowingly because it produces foul-smelling fruit.

During the spring, the new leaves and catkins emerge simultaneously on the tree branches. The male catkins are about 1 inch long and have densely packed anthers that give them a green beady appearance. When the anthers open, the catkins turn slightly yellow and the anthers no longer remain densely packed. (See pictures below)

A male tree releases pollen for about 6 weeks during spring.

a long branch of a tree with its large trunk in the background. The branch has green new leaves and some beady catkins that are about one inch long.
Ginkgo catkins among new leaves during spring. The catkins are still immature and not ready to release pollen.
the male catkins in this tree are yellow green and are loosely packed.
Ginkgo tree catkins that are mature and releasing pollen.

The female trees are rare to find in the cities. However, they do exist. This is what they look like:

Fleshy, wrinkly, yellow fruit balls, about 1 inch in size, in a bunch packed around the tree branch.
A female Ginkgo biloba tree with fruit. The fruit emits a foul smell.

When do ginkgo trees release pollen?

Ginkgo biloba generally releases pollen during spring between March-15th and April-30th in the San Francisco Bay Area.

Depending on the amount of rainfall and weather, the pollen season could differ slightly from one year to the next. This is why it is important to learn to recognize the trees and their pollen-producing flowers.

However, if you live in the San Francisco Bay Area, you have an easier way out! I do regular tree inspections and air sampling in the area to provide reliable pollen updates on our website

What does the ginkgo tree pollen look like?

Ginkgo tree pollen is unique in that it only has one furrow. The furrow itself is smooth, but the rest of the exine has an irregular and warty surface. Round, ~32 microns, monocolpate.

The pollen is fine yellow powder but airborne individual grains are invisible to the naked eyes.

A round pink pollen with a smooth bulging furrow. The remaining three quarters of the pollen has irregular and warty surface
Ginkgo pollen at ~400x magnification.

To see the pollen of other plants and trees, visit our pollen library.

What do ginkgo trees look like?

The ginkgo leaves are its most distinctive trait. The green fan-shaped leaves have a slightly yellow border. The leaves turn bright yellow during autumn.

The trees are deciduous and they lose all their leaves during winter.

The tree forms an oval canopy when young but it starts to spread out as the tree gets older.

The tree bark is brownish-grey and has irregular ridges.

The city trees are generally 25-30 feet tall, but in the wild, they can grow to 80 feet.

About 15, green, fan-shaped, leaves on a twig.
Ginkgo biloba leaves.
A tree, about 25 feet tall, with a green spread canopy
A Ginkgo biloba tree in spring bloom.
A bright orange-yellow tree with a dense canopy
A Ginkgo biloba in autumn.
a brownish-grey, irregularly ridged bark and single tree trunk
The tree trunk and bark of a mature Ginkgo biloba tree.

Key takeaway

The Ginkgo biloba tree is not known to be a major allergen. However, it does produce pollen in spring, which is wind-transported.

Sources

  1. https://plants.usda.gov/
  2. http://dendro.cnre.vt.edu/dendrology/factsheets.cfm

References

  1. Allergy Plants by Mary Jelks, M.D.
  2. Plant identification terminology by James G. Harris and Melinda Woolf Harris (Second Edition)
  3. Sampling and indentifying pollens and Molds by E. Grant Smith
  4. The trees of golden gate park and San Francisco by Elizabeth McClintock PhD.

All pictures, unless otherwise credited to another source, are taken by the author and are copyrighted material. The pollen picture is taken in our aerobiology lab using an Olympus compound microscope. The use of pictures is permitted with a link back to the source page on the internet, or, an attribution to allerma.com on the printed material.

Sudhir Setia

Sudhir is certified by the National Allergy Bureau (NAB) as a pollen counter and identifier. He has been living with Hay Fever for nearly 30 years and studies allergens at his aerobiology lab.

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