1a	Spikelet usually cylindrical or narrowly ellipsoid as wide as culms	2
1b	Spikelet ovoid to narrowly ovoid, rarely cylindrical usually wider than culm	4
2a	Culms with transverse septa, spikelet with basal two glumes empty, achene smooth	E. dulcis
2b	Culms without transverse septa, spikelet with only basal-most glume empty, achene surface cancellate or reticulate	3
3a	Culms terete, sometimes weakly 3-angled; achene apex lacking constriction	E. ochrostachys
3b	Culms sharply 3-angled, achene apex with a distinct constriction	E. acutangula
4a	Persistent style base scarcely differentiated from achene apex and seemingly a continuation of it	5
4b	Persistent style base differentiated from achene apex by a constriction or articulation at the junction with it	6
5a	Plant annual, achene winged or angled, reticulate to deeply pitted-reticulate with isodiametric epidermal cells	E. retroflexa
5b	Plant perennial, not winged or angled, smooth	E. quinquiflora
6a	Stigmas 3	7
6b	Stigmas 2	8
7a	Culms acutely angled, spikelet not proliferous	E. tetraquetra
7b	Culms terete, spikelet usually proliferous at base	E. congesta
8a	Annual, persistent style base not spongy thickened	E. atropurpurea
8b	Perennial, persistent style base spongy thickened	9
9a	Only lowermost glumes empty, surrounding the spikelet base completely or 3/4 of it	E. uniglumis
9b	2 or 3 basal glumes empty, the lowermost glume surrounds about 2/3 of the spikelet base	E. palustris