Stygius: 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. 

	Tepals not subtended by a pair of bracteoles; flowers borne in tight clusters of 2 -100 (sometimes 1-flowered in Juncus stygius var. americanus), these clusters (glomerules) subtended by small bracts; leaf  blades septate (in most species) or not.  NOT [Tepals subtended by a pair of floral bracteoles immediately below the flower; flowers borne singly in the inflorescence either +/- evenly distributed or +/- grouped in loose clusters (not in tight clusters, and if grouped in clusters individual flowers and paired floral bracteoles are still visible and not so tightly crowded such that individual flowers cannot be fairly easily identified); leaf blades, if present, not septate.]
	Leaf blades terete or +/-canaliculate or +/- flattened dorsiventrally (not flattened laterally or equitant), usually < 3 mm wide.  NOT [Leaf blades flattened laterally (folded lengthwise), ensiform and equitant, 1.5 - 6 mm wide.]
	Primary bracts not distinctly white-scarious, may be somewhat but not broadly inflated at base, apices obtuse to acute; tepals with margins narrower, to one-third width of tepals, indistinct or membranous or scarious; anthers much shorter to 2 times longer than filaments; styles of various lengths; capsules variously locular with mucros to 0.5 mm (0.5 - 0.7 mm in J. castaneus) or gradually tapering into long narrow beaks; leaf blades terete or subterete (laterally flattened to subterete in J. nevadensis) or canaliculate (J. castaneus, which is recorded only from the ne corner of the province), septate or indistinctly septate.  NOT [Primary bracts distinctly white-scarious and conspicuously inflated at the base, apices narrowly attenuate to caudate; tepals with wide (>= one-third width of tepals) scarious margins; anthers 2 - 3 times longer than filaments; styles 0.6 - 0.9 (1.2) mm long; capsules 3-locular with (0.5) 0.6 - 1.0 (1.1) mm long mucros; leaf blades +/- canaliculate, not septate.]
	Plants without the following combination of characteristics (but note that the glomerules may be solitary or few).  NOT [Glomerules solitary (rarely 2), (1) 3 - 4 (5)-flowered; primary bracts about equal to inflorescences in length; leaves all basal, blades 0.3 - 1 mm wide, 20-80 (100) mm long, with apices blunt, black and callose; anthers ca. one-quarter filament length; plants 3-25 (35) cm high, recorded from only 2 locations in northern boreal and subarctic transitional forest regions.]
	Capsules (5) 5.5 - 8.5 (9) mm long, long-exserted; seeds 2.4 - 3.5 mm long including conspicuous 0.8 - 1.1 (1.6) mm long apicula; leaf blades indistinctly septate; not found south of the boreal forest.  NOT [Capsules shorter, up to 5 mm long (except up to 5.7 mm long in Juncus torreyi), included or exserted; seeds 0.4 - 1.2 mm long with very short apicula; leaf blades mostly distinctly septate (septa externally indistinct in Juncus mertensianus).]
	Plants cespitose, rhizomes short; sheaths with wide membranous margins; leaf blades 0.4 - 0.8 mm wide; glomerules 1 - 3 flowered; sepals (3.5) 4- 5 mm long, lanceolate to lance-ovate, olive-green and red-tinged near apices with 3-veined midribs; capsules 5.5- 7 (9) mm long, pseudo-3-locular; anthers 0.3 - 0.5 mm long; rare to uncommon in northern boreal and subarctic transitional forest regions.  NOT [Plants with elongate rhizomes with long internodes and few branches; culms solitary at rhizome nodes; sheaths with narrow brownish membranous margins; leaf blades (1) 1.5 - 4 mm wide; glomerules 2 - 10 flowered; sepals 4.5 - 6.5 mm long, linear-lanceolate, dark to dark chestnut-brown with prominent reddish brown midveins prolonged into awn-tips, capsules (5) 6.5-8.5 mm long, 3-locular; anthers 0.6 - 1.3 mm long; recorded only from the ne corner of the province.]

Juncus: 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. 

Leaves various, glabrous; sheaths open, often with margins projected as auricles; flowers with or without a pair of floral bracteoles immediately below the tepals; capsules 1- or 3-locular (or pseudo- or incompletely-3-locular), placentation axile or parietal; seeds many.  NOT [Leaves +/- flat and grass-like, sparsely to densely ciliate; sheaths closed (or sometimes partially splitting later), auricles absent; flowers with 1 - 2 floral bracteoles immediately below the tepals; capsules 1-locular, placentation basal; seeds 3.]

Juncaceae: 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]
	flowers not in globular heads; NOT [flowers in globular heads, the upper ones staminate, the lower ones pistillate]
	flowers in branched inflorescences; NOT [inflorescence a dense, single, cylindrical spike 8-15 cm long, 1-2.5 cm thick], NOT [flowers in spike-like racemes]
	perianth in two whorls, each of three segments
	perianth segments inconspicuous and scale-like; NOT [perianth segments conspicuous and often brightly colored], NOT [perianth of greenish sepals and petals]