a symbiotic association of the mycelium of a fungus, esp. a basidiomycete, with the roots of certain plants, in which the hyphae form a closely woven mass around the rootlets or penetrate the cells of the root.
my·cor·rhi·za or my·co·rhi·za (mī'kə-rī'zə) n.
pl.my·cor·rhi·zae or my·co·rhi·zae (-zē) or my·cor·rhi·zas or my·co·rhi·zas The symbiotic association of the mycelium of a fungus with the roots of certain plants, such as conifers, beeches, or orchids.
[myco- + Greek rhiza, root; see wrād- in Indo-European roots.] my'cor·rhi'zal adj.