Fringeleaf Wild Petunia is a native erect perennial that grows to about one foot high on light green 4-angled stems covered with fine hair. Stem branching occurs.
The leaves are opposite, lanceolate to ovate in shape, up to 2-1/2 inches long, smooth margins, with fine whitish hair on the upper and lower sides and on the very short stalk.
The inflorescence is a solitary 5-parted funnel shaped flower that grows from the leaf axils. The 5 corolla lobes are light lavender to light purple in color, are fused at the base and then separate at the top into spreading flared lobes. The long lobes of the corolla, from 1-1/4 to 2-3/4 inches long, give the appearance of the flower having a stalk, but it usually does not. Inside the funnel of the corolla there are darker purple nectar guide lines; four stamens with lilac to tan anthers that are united as pairs at their bases, with one pair being longer than the other pair; the pistil has a white or lilac colored style. There are 5 sepals that have erect linear pointed lobes with bristly hair along the edges. Flowers are subtended by lance shaped bracts.
Seeds: Fertile flowers produce a 2-chambered capsule containing 3 to 8 seeds per chamber. The seeds are smooth and have coiled threads so that when the chamber splits, these can explosively propel themselves away from the plant. Seeds require 70 days of cold stratification for germination.
Habitat: Fringeleaf Wild Petunia is adaptable to various soils, but needs full sun to flower best. Moisture conditions run from mesic to dry. The plant is not common in its native areas and is usually restricted to prairie areas with low growing vegetation as it does not compete well with taller plants. The root system is composed of numerous slender rhizomes which allow the plant to vegetatively propagate.
Names: The genus, Ruellia, is named for the early French herbalist, Jean Ruelle (1474-1537). The species, humilis, is Latin for low-growing or humble, referring to the low height of this species. The author name for the plant classification - ‘Nutt.’ is for Thomas Nuttall (1786-1859) English botanist who lived and worked in America from 1808 to 1841. On his many expeditions he collected many species that had been originally collected by Lewis and Clark but lost by them on their return journey. He also collaborated with French botanist Francois Andre Michaux (1770-1855) in Michaux’s 3 volume North American Sylva. As to all the alternate common names, they are self-explanatory based on the description of the plant.
Comparisons: This plant has many variable characteristics, such as leaf shape, amount of hairiness, size of flower, not to mention the resemblance to the cultivated annual petunia, which is in an entirely different plant family.
Above: A group of plants. The inflorescence is a solitary 5-parted funnel shaped flower that grows from the leaf axils.
Below: The The darker purple lines inside the corolla are nectar guides for insects.
Below: 1st & 2nd photos - Leaves and leaf stalks are covered with whitish hair, as is the central stem which is 4-angled. 3rd photo - The long lobes of the corolla appear to be a flower stalk but rise above the pointed linear sepals, just visible in the photo. The calyx is in the leaf axil.
Below: 1st photo - The leafy bracts at the base of the corolla tube are pointed and hairy. 2nd photo - The ridges of the corolla and the outer surface has fine hair. 3rd photo - The longer pair of stamens and the style is visible in this photo.
Below: 1st photo - The root system is composed on numerous slender rhizomes which allow the plant to vegetatively propagate. 2nd photo - The two-chambered seed capsule that allows seeds to eject explosively when it opens.
Notes: Fringeleaf Wild Petunia is not indigenous to the Garden as it is possibly not native to Minnesota. It has not been listed on a previous Garden census. In 1947 Curator Martha Crone noted planting R. ciliosa (currently classified as Ruellia caroliniensis var. cinerascens. But Martha did not specify a variety or subspecies and there is one variety of R. ciliosa (var. longiflora) that is now considered a variety of R. humilis, so it is possible the plant had been in the Garden earlier, but she did not list it on her 1951 census.
The current Garden Curator, Susan Wilkins, introduced the species in 2005, some of those photographed here were in the Garden in July 2012. There are references to the plant being native to Minnesota in Washington County and the DNR has it listed as such but also listed on the Minnesota "Special Concern" List. The University of Minnesota Herbarium reports there are no collected examples. If the plant is, or ever was, in Minnesota, it would be the only species of the Acanthus family to be present (Ref. #28C). It is found in the U.S. in the central and eastern states, except the New York - New England area and west as far as Iowa and Nebraska then south to the Gulf. In Wisconsin it is on the endangered list. It is an easy prairie plant to grow and plants or seeds are available from native plant suppliers.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"