Eleocharis robbinsii Oakes. Robbins’s Spikerush. Phen: Jul-Aug. Hab: Quiet waters of limesink (doline) ponds, natural lakes, millponds and semipermanent impoundments. Dist: NS and NB west to ON, south to s. MS (Sorrie & Leonard 1999); also near the Great Lakes, from NY west to IN, WI, and MN.

ID notes: Submersed plants of E. robbinsii can often produce flaccid, filiform culms with internally incomplete transverse septae and sometimes whorls of slender branches. At this stage it is virtually indistinguishable from E. elongata, which it sometimes grows with, although E. robbinsii tends to have fresh culms more trigonous. Dried specimens of E. robbinsii sometimes appear to have ribbed culms (from internally septae); however, these appear to be much less evident on fresh culms.

Origin/Endemic status: Native

Synonymy ⓘ: = C, F, FNA23, G, GW1, K1, K3, K4, Mi, NE, NY, Pa, RAB, S, Tat, Va, WH3, Angelo, Rosen, & Lange (2020)

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: OBL
• Eastern Mountains and Piedmont: OBL
• Midwest: OBL
• Northcentral & Northeast: OBL

Heliophily ⓘ: 9