Sparganium glomeratum
Sparganium natans
cluster bur-reed, northern bur-reed, rubanier aggloméré
arctic bur-reed, rubanier nageant, small bur-reed, small bur-reedl
stiff, weakly keeled, to 50 cm × 6 mm.
limp in water, unkeeled, flat, 0.04–0.6 m × 2–6(–10) mm;
leaves of stranded plants shorter, firmer.
rachis unbranched, condensed, erect;
bracts ascending, somewhat inflated near base; pistillate heads 2–6, mostly supra-axillary, sometimes opposite bract above, upper crowded, sessile, proximal head not contiguous with upperdistal, peduncled, 1.2–1.6(–2) cm diam. and contiguous in fruit; staminate heads 1(–2), contiguous or not with distalmost pistillate head.
rachis unbranched, flexuous;
bracts ascending, basally inflated; pistillate heads 1–3, axillary, not contiguous, sessile or most proximal short-peduncled (often long-peduncled in Alaska and nw Canada), 0.5–1.2 cm diam. in fruit; staminate head 1 or apparently so, terminal, not contiguous with distalmost pistillate head.
tepals without subapical dark spot, entire to erose;
stigma 1, lanceolate.
tepals without subapical dark spot, erose;
stigmas 1, lance-ovate.
greenish brown, lustrous, stipitate, fusiform, body not faceted, slightly constricted near equator, 3–6 × 2–3 mm, tapering to beak;
beak straight, 1.5–2 mm;
tepals attached at base, reaching 1/3 to 1/2 length of fruit.
dark greenish or brownish, subsessile, body ellipsoid to obovoid, not faceted, barely or not constricted at equator, 2–4 × 1–1.5 mm, tapering to beak;
beak curved, 0.5–1.5 mm;
tepals attached at base, reaching about to equator.
1.
1.
= 30.
= 30.
Sparganium glomeratum
Sparganium natans
Sparganium glomeratum is apparently rare, or perhaps is only rarely collected, in North America, except it is locally common in sedge-marshes and black-ash swamps near the western end of Lake Superior. The species is rather invariable throughout its circumboreal range (C. D. K. Cook and M. S. Nicholls 1986).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
This species has long been known as Sparganium minimum, but although the correct name is S. natans (C. D. K. Cook 1985).
The leaves of Sparganium natans are thinner and more translucent than those of the similar S. hyperboreum, and they lack the yellowish cast of that species. Its distalmost pistillate head is not contiguous with the staminate head, as is sometimes the case in S. hyperboreum, and its beaked fruit also distinguishes it from that species. See the discussion under S. hyperboreum for a description of S. hyperboreum × S. natans.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
IL Wildflowers, 
MI Flora, 
MN Wildflowers, 
PNW Herbaria, Turner Photog. 
WildflowerSearch
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USDA Plants Database- LBJ Wildflower Center
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