Species of the Month: January 2019


Bartheletia paradoxa (Ginkgo biloba fungus)


Bartheletia paradoxa is a fungus which appears on the decaying leaves of Ginkgo biloba, otherwise known as the Maidenhair Tree. Fungal spore growth results in black specks in the center of small brown spots on the leaves and stalks. Bartheletia paradoxa is not known to affect any other species, and is probably present on the decaying leaves of all Ginkgo biloba trees in the UK.

Not much is know about the fungus, which was only formally described in 2008, but national maps show south Wales as a "stronghold" for the species, thanks to the efforts of the Glamorgan Fungus Group to find and record it in the area. We would love to continue to increase records of this easy to identify but chronically overlooked fungus.

You can view the known Welsh distribution here on Aderyn; more information can be found on NatureSpot and this Reading University blog.


The first step to finding the fungus is finding and identifying the host species, Ginkgo biloba. As an ornamental tree originating in China, this species is generally only found in parks and garden. The tree can grow up to 40m tall, and has distinctive fan-shaped leaves that resemble Maidenhair Fern. The leaves turn bright yellow in autumn before falling to the ground, which is when the fungus will appear.

Please record any trees you find as well as the fungus, so we can get a better understanding of where Ginkgo biloba have been planted. More information on this interesting "living fossil" can be found on NatureSpot and Arkive. You can view the known Welsh distribution of Gingko bilboa here on Aderyn.


Image taken by Jean-Pol GRANDMONT - travail personnel, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=3108744

If you spot Bartheletia paradoxa or Ginkgo biloba during January (or at any other time of year), please send us the record, ideally via our Species of the Month form on SEWBReCORD (nb. you will need to be signed into SEWBReCORD to use this link). Instructions on how to submit records are available here.