In article , Iris Cohen
writes
You can even assign orchids to taxonomic groups depending on the mycorrhiza
they favor.

Where on earth did you get that idea?

It's not inherently wrong. Coevolution of host/parasite or
symbiote/symbiote relationships leads to a correlation between the
phylogenies of the two taxa, so the identity of the mycorrhizal symbiont
of an orchid species is evidence for its taxonomic position within
Orchidaceae. How much weight should be given to such traits, however, is
not something on which I am in a position to comment.
--
Stewart Robert Hinsley