Fungi and trees

Kew's expert mycologist Martyn Ainsworth guides us through the intimate relationship shared between trees and fungi, and tells us where you can find rare tree-associated fungi at Kew Gardens.

The well-known fly agaric (Amanita muscaria) (Image: Geoffrey Kibby)

A fun(gi) time of year

Although the dedicated fungus-hunter or field mycologist, as they prefer to be called, can always find some fungi fruiting regardless of the time of year, September to October is traditionally regarded as Britain’s mushroom season. This is the time when many larger fungi break cover to produce their fruitbodies (such as mushrooms and toadstools) and shed their spores. Rather like a firework display, stores of energy are rapidly mobilized to produce a short-lived but spectacular display of fascinating form and eye-catching colour.

A mutual partnership

The relationship between fungi and trees is ubiquitous and intimate. Indeed the structures we call trees consist of a very obvious plant and less obvious, but no less important, communities of fungi living in and on the roots, branches, leaves and fruits.

Look out for the golden gilled bolete (Phylloporus pelletieri) at Kew Gardens. Martyn Ainsworth )

The underground world of roots is also the world of mycorrhizal fungi such as the well-known fly agaric (Amanita muscaria). The microscopic filaments of the fungus clasp the roots in a nutrient-trading embrace which is beneficial to both partners. Sugars manufactured high in the tree’s canopy pass down the trunk through the roots and cross over into the fungus to be used in fruitbody construction.

Other tree-associated fungi such as the legally-protected bearded tooth (Hericium erinaceus) prefer to dine on food that has been aged for much longer. Such species inhabit the old dead wood in the central cores of trees. They slowly sculpt homes for other wildlife, such as insects, bats and birds, as they feed and hollow out the trunks of veteran trees.

Fungi to look out for at Kew

Kew Gardens is home to a pair of tree-associated fungi which are legally recognised as being of principal conservation importance in England. They are the golden gilled bolete (Phylloporus pelletieri), which is mycorrhizal, and the zoned rosette (Podoscypha multizonata) which fruits from buried roots. Both species should be sought in open woodland near mature oak or beech and the bolete can also be found with sweet chestnut. They have been spotted in areas around the Lake and Minka House and autumn is the time to be looking...