Species: Eleocharis parvula (Roemer & J.A. Schultes) Link ex Bluff, Nees & Schauer

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Eleocharis parvula (Roemer & J.A. Schultes) Link ex Bluff, Nees & Schauer

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TAXONOMY

Family:

Cyperaceae

Genus:

Eleocharis

Species Synonyms:

Eleocharis parvula var. anachaeta (Torr.) Svens.
Eleocharis parvula var. coloradoensis (Britt.) Beetle
Eleocharis leptos (Steud.) Svens.
Eleocharis leptos var. coloradoensis (Britt.) Svens.
Eleocharis leptos var. johnstonii Svens.
Eleocharis membranacea Gilly
Eleocharis coloradoensis (Britt.) Gilly

Common Names:

dwarf spikerush
dwarf spikesedge
little-head spikerush
small spikerush

DISTRIBUTION

Canada:

southwestern Saskatchewan

Saskatchewan:

southwestern Saskatchewan; Webb – Tessier

Ecoregion:

Moist Mixed Grassland, Mixed Grassland

HABITAT

Saskatchewan:

moist shores of saline lakes

Associated Species:

cosmopolitan bulrush, dock, rayless alkali aster, salt-marsh spurry

RARITY STATUS

Provincial Status According
to Harms (2003):

Threatened

Nature Conservancy Status:

G5 N3 S1

Saskatchewan Species at
Risk Status:

None

COSEWIC Status:

None

Dwarf spikerush is threatened in Saskatchewan because it is extremely rare and is limited to one general region of the province. This species is usually locally numerous but within limited areas. Possible threats have been identified for this species. Dwarf spikerush has not been reported elsewhere in Canada and the Saskatchewan populations may represent a northern range extension.

SPECIES DESCRIPTION

Height:

2 – 7 cm

Roots:

rhizome short, terminated by J- or U-shaped structures; enlarged structures at stem base 4 – 5 mm long, narrowly spindle-shaped, straight

Stems:

perennial, mat-forming, thread-like, round in cross section

Leaves:

blade bearing leaves absent; leaf sheaths short, membranous

Inflorescence:

spikelet terminal, solitary, erect

Spikelets:

2 – 4 mm long, ovoid; floral scales 6 – 10 per spikelet, oval, lowest one empty, entirely straw-coloured or green to brown

Flowers:

2 – 9 per spikelet, perfect; perianth bristles 6 or absent, stout to slender, usually about same length as achene, straw-coloured; styles 3-cleft

Achenes:

egg-shaped, thickly three-angled, angles distinct, straw-coloured or pale brown or black; swelling at base of style short

ELEOCHARIS KEY FOR SPECIES FOUND IN SASKATCHEWAN

1 Achenes with 9 – 13 longitudinal rows of horizontal ridges between prominent longitudinal ridges and achene angles; spikelets with lowest scale always subtending a flower; stems to 1.5 mm wide	E. acicularis
1 Achenes without long rows of horizontal ridges; lowest scale subtending a flower or empty; stems to 5 mm wide	2

2 Swelling at tip of achene conical, confluent with achene; stigmas 3	3
2 Swelling at tip of achene well-differentiated; stigmas 2 or 3	4

3 Spikelets to 3 mm long, internodes equal in thickness and length throughout the spikelet; scales 5 – 500 per spikelet, green or pale brown; stems < 10 cm tall; rhizome lacking a bulb	E. parvula
3 Spikelets to 7 mm long, proximal internodes thicker and shorter than internodes in the middle of the spikelet; scales 4 – 12 per spikelet, tinged with purple or brown; stems to 40 cm tall; rhizomes bulbous	E. quinquefolia

4 Styles 2-fid; achenes convex	5
4 Styles 3-fid; achenes three-sided	7

5 Tufted annuals, roots fibrous; achenes green, straw-coloured, or black; anthers 0.2 – 1 mm long	E. engelmannii
5 Perennials with rhizomes or runners; achenes yellow to dark brown; anthers 1 – 2.5 mm long	6

6 Tip of uppermost leaf sheath with distinct tooth on all or some stems; base of spikelet with single empty scale nearly enclosing stem	E. erythropoda
6 Tip of distal leaf sheath without distinct tooth on all stems; base of spikelet with 2 or 3 firm, empty scales	E. palustris

7 Achenes biconvex (or < 1/3 of achenes trigonous); tufted annuals; spikelets never proliferous	E. engelmannii
7 Achenes trigonous; annuals or perennials, rhizomatous or stoloniferous; spikelets may be proliferous	8

8 Achene surface honey-comb netted; swelling at tip of achene broader than high; stems to 90 cm tall	E. elliptica
8 Achene surface minutely wrinkled or roughened but not netted; swelling at tip of achene longer than broad; stems to 40 cm tall	9

9 Spikelets < 5 mm long; stems 4-angled and capillary	E. nitida
9 Spikelets to greater than 1 cm long; stems flat and wiry	E. compressa