What type of sybiotic relationship does a orchid and tree have?

it is commensalism because the tree has a place to grow but nothing happens to the orchid.

The symbiotic relationship depends on what orchid.

A fungus dependent terrestrial Orchid like Dipodium punctatum (or the hyacinth orchid), has a certain relationship between a type of tree because of a certain fungi that lives in the ground off that tree. It is only that certain type of fungi that Dipodium punctatum can live on because the species of orchid has no leaves, and so lives off the fungus through it's root system.