Eleocharis aestuum Hines ex A. Haines. Subgenus: Eleocharis. Section: Eleogenus. Series: Ovatae. Common name: Tidal Spikerush. Phenology: Jul-Oct. Habitat: Freshwater tidal rivers. Distribution: ME south to DE, PA, and NJ. See McAvoy (2021) for details about DE occurrence.

Origin/Endemic status: Native

Taxonomy Comments: Described by Haines (2003), Eleocharis aestuum has white or brown-tinged scales with round apices, a larger tubercle (0.2-0.3 mm), and a preference for tidal habitats vs. E. diandra, which has purple-brown scales with keeled apices, a smaller tubercle (0.1-0.2 mm), and a preference for freshwater habitats. Eleocharis diandra has never legitimately been documented from the northern extent of our flora region (PA, Long Island) and only from further north (CT northward, likely extirpated in Onondaga Co., NY). Both taxa are globally rare and only E. aestuum occurs in our region (NJ; historical in MD). Only one specimen could be found that is listed as E. diandra from Bucks County, PA (Dreisbach 1864, MICH), but it is not cited or annotated by Haines, or others. This single specimen likely represents E. aestuum given its proximity to the Delaware river, or potentially another taxon in the E. ovata complex.

Synonymy ⓘ: = Can, FNA23, K4, NE, NSProv, NY, POWO; = n/a — Pa, Tat; < Eleocharis ovata (Roth) Roem. & Schult. — C. Basionym: Eleocharis aestuum Hines ex A.Haines 2001

Links to other floras: = Eleocharis aestuum - FNA23

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Wetland Indicator Status:

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

Heliophily ⓘ: 9