Elatine americana (Pursh) Arnott

Locations ofElatine americana (Pursh) Arnott in Virginia

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Detail

Family
Elatinaceae
Botanical Name
Elatine americana (Pursh) Arnott
Common Name
American Waterwort
Synonym(s)
Elatine triandra Schkuhr var. americana (Pursh) Fassett
Flora of Virginia Name/Status
Elatine americana (Pursh) Arnott
Comments
Species delimitation in Elatine is problematic at best, with some authors recognizing three species, others only one. Vegetative features are polymorphic, as exemplified by Fassett's recognizing four varieties (including var. americana) and three additional forms within E. triandra (Rhodora 41:367-375 (1939))! Seed sculpturing is considered a more reliable basis for classification, yet seeds are minute, being comparable in size to Isoetes megaspores (400-700 micrometers). In Virginia, these tiny plants mostly occur on tidal shores and mudflats, where three species names (E. triandra, E. americana, E. minima) have been applied. While there appears to be good reason to question the "splitters" approach, the question remains as to how many species to recognize. A study of environmental effects coupled with modern electron microscopy of seed sculpturing, is a project waiting to happen.

According to Crow & Hellequist (Aquatic and wetland plants of northeastern North America, Vol. 2, 2000), Elatine triandra occurs only north of VA, with E. americana in our area and southward. Therefore, at least tentatively, we are recognizing E. americana and E. minima, occurring here near its southern limits, as the two representatives of the genus in Virginia.
Habitat
Freshwater intertidal shores; rarely in artificial ponds. Rare, known only from fresh tidal shores of the c. and n. Coastal Plain, with an anomalous record from a pond in the c. Piedmont (Albemarle County).
Native Status
Native

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