Glume

In botany, a glume is a bract (leaf-like structure) below a spikelet in the inflorescence (flower cluster) of grasses (Poaceae) or the flowers of sedges (Cyperaceae). There are two other types of bracts in the spikelets of grasses: the lemma and palea.
In grasses, two bracts known as "glumes" form the lowermost organs of a spikelet (there are usually 2 but 1 is sometimes reduced; or rarely, both are absent). Glumes may be similar in form to the lemmas, the bracts at the base of each floret. 
In sedges, by contrast, a glume is a scale at the base of each flower in a spikelet.