Erythropoda: Answers to key questions in Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan by V. L. Harms, A. L. Leighton, and M. A. Vetter leading to this species. The answers are in the order you would normally work through the key. 

	Plants perennial, usually mat-forming; rhizomes present; tubercles, when clearly differentiated, distinctly less wide than achenes.  NOT [Plants annual, with culms densely cespitose; rhizomes absent; tubercles nearly as wide as achenes.]
	Tubercles clearly differentiated; achenes rounded distally and distinct from tubercles; bulbs and tubers absent.  NOT [Tubercles not clearly differentiated; achenes tapering or narrowly truncate distally, often similar to tubercles in color, texture and form; bulbs or tubers often present on rhizomes and/or at culm bases.]
	Achenes without fine horizontal ridges, biconvex or trigonous to nearly terete; proximal scale of spikelets empty.  NOT [Achenes with 30 - 60 fine horizontal ridges (trabeculae) and ca. 8 - 12 longitudinal ridges and achene angles, trigonous to nearly terete; proximal scale of spikelets fertile (subtending flowers, not empty).]
	Styles bifid, (very rarely trifid in E. palustris); achenes biconvex (rarely trigonous in E. palustris); achene surface smooth at high (30X) magnification; spikelets 3 - 25 mm long (ours usually 5 mm or longer); longest rhizome internodes 5 - 60 mm long.  SK species in the E. palustris complex.  NOT [Styles trifid, sometimes bifid; achenes trigonous or biconvex; achene surface roughened at high (30X) magnification; spikelets 4 - 8 mm long (ours usually at most 5 mm long); longest rhizome internodes 2 - 10 mm long.  SK species in the E. tenuis complex.]
	Proximal scale of spikelets clasping around the whole culm (amplexicaulous); subproximal scale of spikelets fertile (subtending flowers, not empty).  NOT [Proximal scale of spikelets clasping two-thirds (to three quarters) of the culm; subproximal scales of spikelets empty.]
	Scales 4 - 5 per mm of rachilla, those in middle of spikelets less than 1.8 mm wide.  NOT [Scales 3 - 4 per mm of rachilla, those in middle of spikelets 1.8 - 2.5 mm wide.]

Eleocharis: Answers to key questions in Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan by V. L. Harms, A. L. Leighton, and M. A. Vetter leading to this genus. The answers are in the order you would normally work through the key. 

	Flowers and achenes naked in the axils of scales, not enclosed in a sac; flowers usually perfect (sometimes some flowers imperfect in Cyperus, Rhynchospora and Cladium).  NOT [Flowers and achenes enclosed in a sac (perigynium) borne in the axils of scales; flowers imperfect.]
	Perianth bristles absent or up to 6 per flower; if more than 6, then only somewhat longer than the achenes.  NOT [Perianth bristles usually more than 10 per flower, much longer than the achenes, conspicuously elongated to over 10 mm long in fruit stage and usually obscuring most scales in spikelets.]
	Inflorescence not a solitary, terminal spike; if solitary, terminal and spike-like, then inflorescence +/- terete.  NOT [Inflorescence a compressed, solitary, terminal spike bearing few-flowered spikelets attached in 2 rows.]
	Inflorescence a solitary terminal spikelet; inflorescence bracts absent or up to 8 mm long and only slightly longer than the spikelet; achenes usually <= 2 mm long (up to 2.3 mm in Eleocharis quinqueflora).  NOT [Inflorescence usually with > 1 spikelet; if only 1 spikelet present, then inflorescence bract usually 10 - 200 mm long (but as short as 7 mm in Schoenoplectus subterminalis) and achenes 2 - 3.5 mm long.]
	Leaf sheaths lacking blades; inflorescence bracts absent (subproximal and proximal scales, especially those lacking flowers, might be mistaken for very short bracts); scales 3 - 500 per spikelet; achenes usually bearing a clearly differentiated tubercle (but see Eleocharis quinqueflora and E. coloradoensis).  NOT [Leaf sheaths with short to long blades; inflorescence bracts present (may be absent at maturity because deciduous but will leave a scar) up to 8 mm long and only slightly longer than spikelets; scales 3 - 20+ per spikelet; achenes lacking a tubercle but sometimes beaked.]

Cyperaceae: Answers to key questions in Budd's Flora leading to this family. 

	plants not aquatic, or if growing in water, most of the plant emersed; NOT [plants aquatic, floating or submerged, with floating leaves or emersed inflorescence]
	culms usually solid; NOT culms usually hollow]
	leaves three-ranked; NOT [leaves two-ranked]
	inflorescence NOT [a dense, single, cylindrical spike 8-15 cm long, 1-2.5 cm thick], if a single spike, less than 1 cm thick
	flowers not in globular heads; NOT [flowers in globular heads, the upper ones staminate, the lower ones pistillate]
	flowers solitary in the axil of a single bract (scale); NOT [flowers enclosed in two-ranked bracts with the lowest (glumes) empty]
	perianth inconspicuous, not in two whorls; NOT [perianth present, conspicuous, in two series of 3 segments, often brightly colored]
	perianth reduced to bristles; NOT [perianth reduced to minute lodicules or lacking]