co·le·o·rhi·za 
(kō′lē-ə-rīzə, kŏl′ē-)
(kō′lē-ə-rīzə, kŏl′ē-)n. pl. co·le·o·rhi·zae (-zē)
A protective sheath enclosing the embryonic root of grasses.
[New Latin : Greek koleon, sheath; see kel-1 in the Appendix of Indo-European roots + Greek rhiza, root; see wrād- in the Appendix of Indo-European roots.]