Ruellia humilis

Ruellia humilis is a small perennial plant called the Wild Petunia or Fringeleaf Wild Petunia in its native United States. There, it grows without care in meadows, forming small tufts of slightly hairy leaves, adorned with small funnel-shaped flowers of a soft blue-mauve colour. These flowers only live for one day, but they continue to bloom throughout the summer on the foliage. Little known and rarely planted in our gardens, this Ruellia is an excellent plant for sunny borders and rockeries, being both floriferous, hardy, and low water-demanding.

Ruellia humilis belongs to the Acanthus family, just like the bear's breeches. This accommodating botanical species is widespread in many states in the northeast, central, and southeast of the United States. In nature, it can be found in meadows, clear and dry understories, clearings, cliffs, sandy plateaus, along railways, in fields, and along roadsides. Its habitat is often characterized by shallow, somewhat calcareous soils. The above-ground vegetation persists more or less in winter in mild climates.

Ruellia humilis quickly forms a vegetation dome of about 40cm (16in) in all directions, more or less depending on the growing conditions. It consists of multiple hairy, branched stems adorned with leaves arranged in an opposite manner. The leaves resemble those of petunias. They are oval-shaped, 6cm (2in) long and 2.3cm (1in) wide, with smooth margins, medium green colour, and covered with white hairs on both sides. Flowering begins in June-July depending on the climate, and continues until August-September. The funnel-shaped flowers with 5 lobes measure 3.5 to 4.5cm (1 to 2in) in diameter and also resemble petunias, like the rest of the plant. They can be solitary or grouped in small clusters in the axils of the upper leaves. They open in the morning and fall in the evening. After pollination by insects, capsules containing oval seeds form and fall to the ground near the mother plant or are ejected up to 2 metres (7 feet) away.

Plant Ruellia humilis as a border plant, along with other perennials such as Aster laevis, Coreopsis, Penstemon digitalis, grasses like Eragrostis spectabilis, or Schizachyrium scoparium for example. In a rockery, it will blend well with silver basket, Montpellier soapwort, Convolvulus cneorum, or Lithodora.