Gratiola viscidula (Short’s Hedgehyssop) is common and widespread in North Carolina, often found along pond and lake margins, and wetlands. Despite its widespread distribution, it is easily overlooked due partly to its small size (rarely reaching 12 inches in height), and to its habitat. It has a fondness for very wet, even partially submerged areas , and so is often found where walking is difficult. It has become popular as an aquarium plant, and can remain submerged for long periods of time.
A cluster of small plants is illustrated below.
Important characteristics that separate Gratiola viscidula from other members of its genus are the clasping leaves, the long flower petioles, the dense, glandular puberulence of the stem, and the three to five teeth along each leaf margin. Initially this plant was thought to be Gratiola neglecta, as the two are very similar. The factor that helps most to separate them is the shape of the base of the leaf. G. neglecta has a base that tapers to the stem attachment, while G. viscidula has a clasping base.
The plant form is pictured below.
The next photo is a closer look at the heavy glandular puberulence of the stem, the flower stems, and the flower bracts. Another common name for Gratiola viscidula is Viscid Hedgehyssop since the glandular puberulence gives the plant a clammy or sticky feel when touched. This characteristic is shared by several other closely related members of the genus, especially Gratiola neglecta, the Clammy Hedgehyssop.
The flowers open mid to late morning. The petals are white and the centers yellow.
Closer views of the flowers.
The flowers of Gratiola viscidula have five petals but two are often fused together.
Plants in the Gratiola genus are conventionally called hedgehyssops, a colorful name said to originate in England, the land of hedges.
Lindernia dubia, the False Pimpernel, is a small wildflower that is sometimes confused with Gratiola viscidula and neglecta. It often appears in similar clustered colonies, has small flowers on very long petioles, and has a very similar habitat and distribution. It also has a penchant for mud and disturbed soil. A colony of False Pimpernel is shown below.
There are a number of ways to distinguish the two wildflowers in the field. Lindernia dubia has only a single pale lilac flower at each leaf axil, while Gratiola viscidula has two white flowers at each axil. G. viscidula has a round, densely puberulent stem, while L. dubia has a smooth, square stem. They both bloom at the same time. Below is a closer view of Lindernia dubia.
In spite of their similar appearance, they are not closely related. Gratiola viscidula is in the Plantain family, the Plantaginaceae, while Lindernia dubia is in the Linderniaceae, a family so new that it has no common name yet.