Vascular Plants of North Carolina
Account for Whorled Marsh-pennywort - Hydrocotyle tribotrys   Ruiz & Pavon
Members of Araliaceae:
Members of Hydrocotyle with account distribution info or public map:
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Section 6 » Family Araliaceae
AuthorRuiz & Pavon
DistributionPresent over nearly all of the Coastal Plain, though likely absent from the northwestern portions, and of spotty occurrence in the southern counties (artifact of collecting?).

This is a mostly Coastal Plain species, ranging from NJ south to southern FL and west to TX, but not ranging into the Piedmont or Mountains like H. verticillata often does.
AbundanceFairly common (apparently) across most of the Coastal Plain, but scarce to locally absent in the northwestern portion, and uncommon in the Sandhills. It appears to be less numerous in the state than in H. verticillata, though for now both are given a State Rank of S4.
HabitatThis is a wetland species like essentially all others in the genus, but habitat data from the NC specimens suggest that it favors open to partly open wetlands. Many records are from ditches and marshes, though certainly it does occur in shaded wetlands such as swamp openings and margins of rivers and creeks.
PhenologyBlooms from May to July, and fruits shortly after flowering.
IdentificationThis species is similar to H. verticillata, in that it is fairly short, with a leaf stalk to about 5-6" tall, and a peltate blade about 2" across, rounded in shape with scalloped margins. The separate flowering stalk is usually taller than the leaves, often to 6-8" high, and the small white flowers are distinctly stalked in the several whorls along the upper part of the stalk. These flowers are white, and the general effect is that in this species, the flower clusters are more apparent and visible -- taller and with more obvious flowers -- than those in H. verticillata, which has its flowers and fruit sessile as opposed to distinctly stalked. These two species are separated from others by the peltate leaves along with all flowers existing on a single axis in whorls, rather than in umbels on the top of stalks or on multiple branches.
Taxonomic CommentsOlder references listed this as a variety of H. verticillata, named as H. verticillata var. triradiata. NatureServe still does.

Other Common Name(s)None
State RankS4
Global RankG5T5? [G5?]
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