Recently I noticed some fungi show up on my Korean Hornbeam bonsai and I assumed they were a form of mycorrhiza fungi but was not 100% certain and whilst I was at the Arboricultural Association Conference at Reading I went to a great lecture by Ted Green who was discussing and sharing his ideas on mycorrhiza associations with tree roots.

I therefore contacted him after the conference and sent him some photos of my bonsai tree and its fungus. He was very interested and also passed the photos onto a colleague Dr James Merryweather and they both identified the fungi as Laccaria laccata which is a classic ectomycorrhizal species.

Laccaria laccata is a smallish agaric mushroom with thick fleshy gills and a fibrous stem. Its colour varies from a pale yellow to brown and changes colour as it develops. It is an ectomycorrhizal species which means it grows typically in the intercellular spaces of the root cortex and around the outside of the root and root tip and it is common on Pineaceae, Betulaceae and Fagaceae families of trees.


Having mycorrhizas in your bonsai pots is beneficial for the following reasons but may not always be present:-

  • Aids with water and nutrient uptake as mycorrhiza greatly increase the roots efficiency at this as they increase the absorptive surface area
  • Aid with alleviating stress and disease as they can combat bacterial diseases
  • They can protect against root pathogens as some produce antibiotics which inhibit root pathogens, or they create an additional physical barrier via their hyphae. They can also stimulate the tree to produce chemical inhibitors by their presence.
  • They alter the root physiology which improves the overall rooting system of the trees.
  • They aid with improving soil structure and increase the organic matter content of soils.