Basic grass morphology and terminology that we will use this semester
1. Spikelet
· spikelet = glumes + florets, as well as the pedicel and rachilla.
· florets = lemma + palea + flower.
· disarticulation above or below glumes. If glumes persist on the plant, then disarticulation is above the glumes. If spikelets disperse in their entirety, then disarticulation is below the glumes.
· awns = stout hairs from lemmas and glumes.
· callus = hardened tissue at base of lemma and derived from rachilla, or hardened tissue at the base of spikelet and derived from the pedicel.
· compression: lateral versus dorsal
2. Inflorescence morphology
· spikes = sessile spikelets
· racemes = pedicellate spikelets with primary branches each ending in a spikelet
· panicles = pedicellate spikelets with secondary branches each ending in a spikelet
3. Leaves
· ligule
· blade
· sheath: open or overlapping edges versus closed or fused edges (as in Bromus and the genera of the tribe Meliceae)
· auricle (with finger-like projections in most of the wheatgrasses or with ear-like flaps in the genus Schedonorus).
· collar (not hairy versus hairy)
· throat (region at the junction of the leaf blade and sheath, by the auricle and collar, on the inside facing the stem)
· stem (traditionally referred to as the “culm” in the grass and grass-like families)
4. Habit
· perennial versus annual
· nodes (intercalary meristems)
· branching of tillers, rhizomes, stolons