Vascular Plants of North Carolina
Account for Smooth Wild-petunia - Ruellia strepens   L.
Members of Acanthaceae:
Members of Ruellia with account distribution info or public map:
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Section 6 » Order Scrophulariales » Family Acanthaceae
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DistributionRemarkably disjunct range in the state, known from collections in three distant counties -- Bertie (along the Roanoke River), Pender, and Richmond; the latter site is within the eastern edge of the Piedmont (Pee Dee River). Also from Halifax County, with an iNaturalist photo from July 2021. The species was not discovered in NC until 1970.

This is a widespread Midwestern species, found in most counties in the central Mississippi River and Ohio River regions. It ranges into much of the central Appalachians, but eastward only sparingly to NJ, NC, and SC.
AbundanceVery rare in the eastern half of the state; all or nearly all of the five known sites are believed still extant. This is a State Endangered species.
HabitatThis is a species requiring rich, high pH soil. The NC sites are in Wet Marl Forests (Pender County), openings along natural levee brownwater forests (Bertie County), and edges of a floodplain forest/base of a Basic Mesic Forest on gabbro (Richmond County). The habitat for the Halifax site is described as a "Nice southern sugar maple calcareous ravine forest to the south with Agrimonia parviflora and Aesculus".
PhenologyBlooms from May into late summer, and fruits shortly after flowering.
IdentificationThis is a quite smooth and robust Ruellia, growing to 2-3 feet tall, much taller than the other NC species. It may have a few branches or be unbranched. The scattered opposite leaves usually have a short petiole, and the blades are fairly large, about 4 inches long and 1-1.5 inches wide, ovate to lanceolate, with entire margins. The flowers are essentially only from axils in the middle of the stem, usually singly at an axil and with a short stalk. The flowers are large, about 2 inches long and about 1-1.25 inches across the front, being lavender to light purple in color. No other Ruellia in NC approaches this one in size, and hardly any others even are over 1.5 feet tall. They are more pubescent, and the common R. caroliniensis has darker purple flowers from the upper leaf axils. To see this species, you likely will have to travel out of state, though it certainly must lurk in a few other rich soil places in the state.
Taxonomic CommentsNone

Other Common Name(s)Smooth Ruellia, Limestone Wild-Petunia
State RankS1
Global RankG4G5
State StatusE
US Status
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B.A. SorrieRichmond County, 2006, Pee Dee Gabbro Slopes area, N of US 74, RichmondPhoto_natural
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