Sparganium Anna Leighton Key
This key was created by Anna Leighton (Harms, V.L., Leighton, A.L., Vetter M.A. 2018, Rushes, Bulrushes & Pondweeds plus the remaining Monocots of Saskatchewan, published jointly by Flora of Saskatchewan Association and Nature Saskatchewan).
1a. Stigmas usually 2, occasionally 1 on some flowers; mature
fruit bodies 5-10 mm long, obpyramidal, abruptly contracted to beaks, sessile,
usually 2-locular and 2-seeded; inflorescences usually branched; leaves
emergent. Sparganium eurycarpum
Giant Bur-Reed C
1b. Stigmas 1; mature fruit bodies usually <5 mm long, ellipsoidal, fusiform
or obovoid, tapering to beaks (+/- beakless in S. hyperboreum), stipitate or
subsessile, 1-locular and 1-seeded; inflorescences branched or unbranched;
leaves emergent or floating. 2
2a. Mature fruiting heads usually <10 mm wide; staminate
heads single or apparently so; fruit bodies subsessile; inflorescences
unbranched. 3
2b. Mature fruiting heads >10 mm wide; staminate heads usually 2 or more (1
in S. glomeratum); fruit bodies distinctly stipitate; inflorescences unbranched
or branched. 4
3a. Lowermost pistillate heads axillary, usually sessile,
sometimes pedunculate; mature fruit short beaked, the beaks 0.5-1.5 mm long;
staminate heads remote from uppermost pistillate head; leaves 2-8 mm wide, thin,
translucent, usually dark green. Sparganium natans
Small
Bur-Reed C
3b. Lowermost pistillate heads supra-axillary; mature fruit essentially
beakless, the beaks <0.5 mm long or absent; staminate heads contiguous or not
with uppermost pistillate head; leaves 1-5 mm wide, rather thick, opaque,
yellowish green. Sparganium hyperboreum
Northern
Bur-Reed End (Lake Athabasca)
4a. Leaves (at least some) emergent, erect-ascending, keeled for
all or part of their length; inflorescences unbranched. 5
4b. Leaves floating and flaccid, unkeeled; inflorescences unbranched or
branched. 6
5a. Staminate heads 3-7 (10); pistillate heads contiguous or not
distally; mature fruiting heads 15-35 mm wide; beaks 2-4.5 mm long. Sparganium
emersum Green-Fruited Bur-Reed C
5b. Staminate heads 1 (2); pistillate heads densely crowded distally; mature
fruiting heads 12-16 (20) mm wide; beaks 1.5-2 mm long. Sparganium
glomeratum Clustered Bur-Reed End (Churchill River)
6a. Inflorescences unbranched; leaves 2-5 (10) mm wide, flat to
plano-convex; staminate heads (1) 2-4 per inflorescence, often contiguous and
appearing as 1 elongate head; pistillate heads not contiguous; beaks of mature
fruit 1.5-2 mm long, +/- straight; tepals not adnate to stipe. Sparganium
angustifolium Narrow-Leaved Bur-Reed C
6b. Inflorescences usually branched, sometimes unbranched; leaves 4-10 mm wide,
flat; staminate heads 3-6 on the main rachis and 1-4 per branch of the
inflorescence, contiguous or not; pistillate heads often contiguous or nearly
so; beaks of mature fruit 2-3.5 mm long, curved; tepals adnate to stipe. Sparganium
fluctuans Floating Bur-Reed UC (boreal, north of Saskatchewan
River)