Vervain family (Verbenaceae)
Description: This native perennial plant is ½2' tall, branching occasionally from the leaf axils. The stems are erect or have a tendency to sprawl, sometimes rooting at the leaf nodes. They are covered with long white spreading hairs. The opposite leaves are up to 3" long and 1½" across. They are pinnatifid and sharply lobed (cleft), but broadly lanceolate or ovate in overall form. The margins are coarsely serrated, while the base of each leaf is sessile or tapers to a winged petiole. The leaves are often pubescent and slightly ciliate, with a rough texture.
The major stems terminate in an inflorescence consisting of a short flattened spike, densely crowded with flowers. The flowers are individually about ½" across, and usually pink or lavender rarely do white or purple forms occur in the wild. The hairy reddish calyx of each flower is partitioned into 5 triangular sepals. The corolla tube is long and narrow, but abruptly flares outward into 5 petals that are sometimes notched at their tips. There is a pleasant floral scent. The blooming period occurs from late spring to early summer, lasting about 2 months. Some plants may bloom later and longer, but this is the exception to the rule. The seeds are without tufts of hair, and may fall to the ground only a short distance from the mother plant. The root system consists of a stout taproot, which may send up multiple stems at the base of the plant.
Cultivation: The preference is full to partial sun, and mesic to dry conditions. The soil can contain rich loam, sand, or gravel. Plants that are not native to Illinois may not be reliably winter hardy in Zone 5. Therefore, it is important to obtain seed or plants that are local to the area.
Range & Habitat: Rose Vervain occurs in scattered counties of Illinois (see Distribution Map). This plant is absent from NW Illinois and some southern areas, otherwise it is uncommon. Some local populations in the wild are undoubtedly plants that have escaped cultivation. It can be difficult to distinguish native from introduced varieties, but the former are more likely to be winter hardy and can persist for decades. Habitats include mesic to dry black soil prairies, sand prairies, gravel prairies, slopes and openings in rocky or sandy woodlands, limestone glades, bluffs, pastures and abandoned fields, and borders of lakes. Pioneer cemeteries and rocky moraines are good locations to discover this plant. Illinois is at the northern end of the distribution for Rose Vervain, which occurs in many southern states.
Faunal Associations: The nectar of the flowers attract long-tongued bees, butterflies, and skippers. The caterpillars of Crambodes talidiformis (Verbena Moth) feed on the foliage. Mammalian herbivores are unlikely to consume this plant because of the bitterness of the leaves. The seeds may be carried off by small rodents or birds, and perhaps dispersed by them to a limited extent.
Photographic Location: The photographs were taken at Loda Cemetery Prairie in Iroquois County, Illinois.
Comments: This is a beautiful plant with flowers that are similar to phlox. However, the ragged appearance of the leaves sets it apart from the latter species. Cultivars offer a greater range of flower colors and their leaves are often dark green. The Rose Vervain in the photographs was located on the gentle north slope of a pioneer cemetery, where a remnant of mesic black soil prairie occurs.