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Wetland Plants and Plant Communities of Minnesota and Wisconsin

BLUNT SPIKE-RUSH

(Eleocharis obtusa (Willd.) Schult.)


Blunt spike-rush

SEDGE FAMILY (Cyperaceae)

IND. STATUS: OBL

FIELD CHARACTERISTICS: Herbaceous, densely tufted annual with fibrous roots. The soft stems are up to 50 cm. in height, 0.5-2 mm. thick with sheaths that are oblique at the apex. Spikelets are ovoid, up to 16 mm. long and manyflowered. Achenes (nutlets) are lens-shaped, obovoid and 0.7-1.2 mm. long with a triangular (deltoid) -shaped cap (the tubercle) that is a different color and texture than the body of the achene. The tubercle is about three-fourths to nearly as wide as the broadest part of the achene. Bristles subtending the achene usually number 6-7 and equal or exceed the length of the achene.

ECOLOGICAL NOTES: Blunt spike-rush is a colonizer of mudflats, shorelines and marshes. It is commonly found in disturbed, saturated soils such as those of farmed wetlands and wetland creation or restoration sites. The authors have chosen to follow the nomenclature given by Swink and Wilhelm (1994) and Voss (1972). Gleason and Cronquist (1991) lump E. obtusa, as well as E. engelmannii (Steudel), under E. ovata (Roth) Roemer & Schultes.

SOURCE: Voss (1972); Swink and Wilhelm (1994); Gleason and Cronquist, (1991); Great Plains Flora Association (1991); and Britton and Brown (1970).


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