Clammy Hedge Hyssop
Figwort family (Scrophulariaceae)
Description: This native annual plant is about 3-10" tall and more or less erect. It form short side branches along the upper half of the central stem, and sometimes branches along its lower half as well. The stems are light green and pubescent. The middle to upper opposite leaves are lanceolate, oblanceolate, or ovate; they are up to 1¾" long and ½" across. In contrast, the lowermost opposite leaves are linear-oblong; they are about the same length as the other leaves, but more narrow. Both kinds of leaves are light to medium green, hairless, sessile, and dentate or smooth along the margins.
Individual flowers develop from the axils of the upper leaves on pedicels up to 1" long. Each flower has a tubular corolla about 1/3" long and a short tubular calyx with 5 teeth. The front of the corolla is mostly white, while its lower exterior is pale yellow or green with fine veins. The outer rim of the corolla has several spreading lobes that are short and rounded. Inside the corolla, there are 2 fertile stamens, 2 abortive stamens, and a slender style. The exterior of the calyx is green and pubescent; its teeth are slender and often recurved. At the base of each flower, there are a pair of small leafy bracts that are lanceolate or lanceolate-linear in shape. The blooming period can occur from late spring into the fall. While this is a long time period, individual plants usually bloom for only 1-2 months before they die down. Each flower is replaced by a small seed capsule that is ovoid and pointed at its apex; it contains many small seeds. The root system consists of a slender branching taproot. This plant spreads by reseeding itself, and it readily forms colonies at favorable sites.
Cultivation: The preference is full sun to light shade, wet conditions, and exposed muddy soil. Shallow water is tolerated if it is temporary. This opportunistic plant develops very quickly from seed when the ground is wet. It also dies down quickly after its seeds become mature.
Range & Habitat: Clammy Hedge Hyssop is occasional to locally common throughout Illinois. Habitats include floodplain forests, muddy depressions in upland woodlands, gravelly seeps, degraded soggy meadows, mud puddles along woodland paths, and poorly drained fields. This little plant likes to colonize disturbed areas.
Faunal Associations: The nectar and pollen of the flowers attract Halictid bees and other small bees. The tiny seeds probably cling to the feet of animals and the shoes of humans as they pass through the muddy areas where this plant grows. Later, these seeds are released into new areas where they may germinate.
Photographic Location: A muddy depression in Busey Woods, Urbana, Illinois.
Comments: This is another small annual in the Figwort family. Unless a large colony happens to be in bloom, it is easy to overlook. Clammy Hedge Hyssop can be distinguished from a similar species, Gratiola virginiana (Round-Fruited Hedge Hyssop), by its pubescent stems and ovoid seed capsules. In contrast, the latter species has succulent glabrous stems and globoid seed capsules. Another small annual in the Figwort family that likes wetland areas, Lindernia dubia (False Pimpernel), lacks pairs of leafy bracts underneath its flowers. Its leaves are usually wider in shape and more shiny than those of Clammy Hedge Hyssop. In spite of the common name, Clammy Hedge Hyssop is not normally found around hedges. This probably refers to the habitat preferences of a European species in this genus.