Vascular Plants of North Carolina
Account for Riverbank Quillwort - Isoetes riparia   Engelmann ex A. Braun
Members of Isoetes with account distribution info or public map:
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Section 1 » Order Isoetales » Family Isoetaceae
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AuthorEngelmann ex A. Braun
DistributionThere is much confusion regarding coastal/tidal collections of this genus, and most specimens of I. "riparia" appear to be of I. appalachiana. Weakley (2020) now considers the species as definitely occurring in NC. The range map below is preliminary.

An Atlantic states species, ranging from ME southward at least to NC, if not also to SC.
AbundanceApparently rare, but unsettled. Weakley (2020) map shows it as "rare" in the Coastal Plain. The website editors will give it a rank of S1S2 for now, and not recommend Watch List until confusion is cleared up.
HabitatWeakley (2020) says "Shores".
PhenologyFlowers and fruits from April to October.
IdentificationSee Weakley (2020).
Taxonomic CommentsThis species has long been valid, but it was recently thought that all NC specimens referred to I. appalachiana, a relatively recently described species. Apparently, a few specimens do refer to I. riparia after all. Our plants are var. riparia.

All Isoetes species are quite grass-like, with numerous very slender and grass-like leaves growing from a common base. Most importantly, they are swollen at the base, where the megaspores are present, the key structure for separation of species. The leaves are terete (rounded) and hollow. For identification, see the key in Weakley (2018).
Other Common Name(s)Shore Quillwort
State Rank[S1S2]
Global RankG5
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