In this association, the absorbing roots are almost completely enveloped by a mantle of very compact hyphae of the fungus. Plant like pines, willows, Picea, Cedrus, Betula develop their characteristic ectomycorrhizae.
The common fungal partners that enters the ectomycorrhuae are species of Cortinarius, Tricholoma, Amanita, Lactarius, Scleroderma. From the external mantle certain hyphae enter the cortex of roots and confine to the intracellular space of the cortical cells. The roots are stunted in growth, swollen due repeated dichotomy, become coral like and finally organised into condensed masses. The stellar portions and also the meristem at the apex are not inhabited by the fungus. Within the cortex of the root, the intercellular hyphae ramify extensively in the form of a reticulum to which the name 'Harting-net' is given (German botanist Hartig found out this).
This kind of mycorrhizae is confined to the cells of the root system; causing internal infections of the cortex of root and rhizome of the plants.
The most important role of the fungus of endomycorrhizae is the disintegration of soil particles and absorption and transport of released particles in to the plants. The formation of endomycorrhizae does not alter the the morphology of the root system. The fungus is confined in the root cells and are grown externally root hairs are normally formed on the surface of the roots.