About Agalinis tenuifolia (Vahl) Raf.
Agalinis tenuifolia (Vahl) Raf. grows 20 to 60 centimeters tall, with a slender stem that branches in a paniculate pattern. Its simple, opposite leaves measure 20 to 50 millimeters long and only 1 to 3.5 millimeters wide. Flowers grow on pedicels that are 10 to 20 millimeters long. Each flower is bilaterally symmetrical, with five fused petals 10 to 15 millimeters long that form a corolla tube, plus four stamens. The fruit is a round dry capsule 3 to 7 millimeters long that splits open when it is ripe. This species is widely distributed across eastern Canada and the United States, though its local distribution may be spotty. It has been recorded in the U.S. states of Alabama, Arkansas, Colorado, Connecticut, Washington, D.C., Delaware, Florida, Georgia, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, Mississippi, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Virginia, Vermont, Wisconsin, West Virginia, and Wyoming, as well as the Canadian provinces of Manitoba, New Brunswick, Ontario, and Quebec. Agalinis tenuifolia is listed as a species of special concern in the U.S. state of Rhode Island. In Virginia, it grows in habitats including dry woods and barrens, and is found particularly in open disturbed areas such as old fields. In Michigan, by contrast, it grows in moist or even marshy ground, including along river banks. This species’ survival in an area depends on having appropriate habitat; it can be eliminated from an area by development, changes in land use, or competition with invasive species. Like other species in the genus Agalinis, A. tenuifolia is hemiparasitic on a variety of host plants, especially graminoids. It uses haustoria to connect its roots to the roots of its host plants, but it also has green tissues and carries out photosynthesis on its own.
