Vascular Plants of North Carolina
Account for Carolina Wild-petunia - Ruellia caroliniensis   (J.F. Gmelin) Steudel
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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Author(J.F. Gmelin) Steudel
DistributionThroughout the Coastal Plain and Piedmont, and scattered over the southern Mountains.

This is a widespread Southeastern species, found in nearly all counties in the range -- from southern NJ and southern IL, south to the Gulf Coast of FL to TX.
AbundanceCommon and widespread in the Piedmont and nearly all of the Coastal Plain, though scarce in the far eastern counties. Infrequent to fairly common in the southern half of the Mountains, but very rare to absent in the northern counties.
HabitatThis species has a wide array of shaded to semi-shaded habitats, generally in somewhat mesic to moist soil. It grows best in open woods, wooded borders, and in medium-growth forests of many types such as Mesic Mixed Hardwood Forests and various oak-hickory forests. It also grows around rock outcrops, somewhat sandy woods, woodland clearings.
See also Habitat Account for General Dry-Mesic Hardwood Forests
PhenologyBlooms from June to September, and fruits shortly after flowering.
IdentificationThis is a very familiar species to biologists across the state, and this is the only common Ruellia species in the state, the one to which all of the other four species must be compared with and ruled out before an identification is made. This is a medium-sized herb, growing erect with a few branches, rarely unbranched. It reaches about 1-1.5 feet tall, and has a pubescent stem, with scattered opposite leaves. The leaf is ovate to lanceolate, 3-4 inches long and about 1.5 inches wide, usually with a short petiole. In this species, the flowers are only from the upper leaf axils and the stem summit, a few per cluster. The flowers of all Ruellia species have tubular bases and widely flared apices, like a petunia or some morning-glories. The flowers are dark lavender to bluish-purple, about 1.5 inches long, with 5 rounded lobes, and a flower spread in the front about 1-inch across. In this species, the flowers are sessile or essentially so; in R. purshiana, the only other species with a moderate range in the state, each flower is on a distinct stalk, often 1-inch long. Also, it has flowers found only from lower and middle axils, never the top ones. The sprawling (in NC) R. humilis is branched at the base, is generally decumbent, the leaves are essentially sessile, and most flowers are white in color. R. ciliosa, found only in the Sandhills region, has a basal rosette, with its flowers essentially at ground level. R. strepens is a quite tall and very smooth, elegant species, with larger leaves and flowers mainly at lower and middle axils.
Taxonomic CommentsThough this has always been a good species, many or most references include at least one of the above species within it, especially R. ciliosa. Weakley (2018) does not list and varieties or subspecies for it.

Other Common Name(s)Common Wild-petunia
State RankS5
Global RankG5
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