Which of the following forms hartig-net in the intercellular spaces...

Ectomycorrhizae form a dense sheath or mantle over the surface of the root. From this mantle, hyphae grow into the intercellular spaces of the root cortex, forming a highly branched network known as the Hartig net. This structure facilitates the exchange of nutrients between the fungus and the host plant.

Endomycorrhizae, on the other hand, penetrate the cell walls of the root cortex to form intracellular structures like arbuscules and vesicles, but they do not form a Hartig net.

Answer: Ectomycorrhizae