I was curious too and found this:
glume (ɡluːm) n
1. (Botany) botany one of a pair of dry membranous bracts at the base of the spikelet of grasses
2. (Botany) the bract beneath each flower in a sedge or related plant
[C18: from Latin glūma husk of corn; related to Latin glūbere to remove the bark from]
gluˈmaceous adj
ˈglumeˌlike adj
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014