Agalinis tenuifolia aka Slender False Foxglove

Agalinis tenuifolia is an annual wildflower called slender-leaved false foxglove. It belongs to the Orobanchaceae family. Its native range spans central and eastern North America. It grows from Maine to Manitoba, south to Florida and Texas. Wild plants grow in woods, fields, prairies, and wet thickets. They also grow beside streams, along shores, and on disturbed ground.

Plants grow upright, with thin branches and a fine texture. Garden plants reach 1–2 feet (0.30–0.61 metres) tall. Their spread ranges from about 0.6–1.5 feet (0.18–0.46 metres). The smooth green stems have angles and narrow ridges. Narrow, simple leaves grow in opposite pairs along them. Their edges are smooth, with a clear central vein. Leaves reach up to 0.25 feet (0.076 metres) long. Dry weather can turn both leaves and stems purple-red.

Pink to purple flowers bloom from August through October. They grow singly where upper leaves meet the stem. Each flower forms a bell or funnel with five lobes. Dark spots mark the pale throat, and hairs fringe the edges. Two small upper lobes form a hood. Three larger lower lobes spread outward. The stamens and style are white. Each bloom lasts only one or two days. Only a few flowers open on each branch at once. Round, glossy seed capsules follow the flowers in fall. Wind carries the seeds away from the plant.

Grow this plant in sun or partial shade. It prefers moist soil that drains well. Sandy and loamy soils suit it, though it tolerates rocky ground. Wild plants also occur in somewhat dry soils. Missouri Botanical Garden lists USDA zones 2–11 for cultivation. The roots may draw some resources from nearby plants. NC State reports this partial parasitism when certain grasses grow nearby. Plants grow at a moderate rate and reproduce by seed. Self-seeding can keep them in the garden from year to year. Some gardens may need fresh sowings each year.

This species suits native gardens, woodland gardens, and naturalized sites. It adds late-season flowers beside ponds and bogs. The blooms attract butterflies and other pollinators. Neither horticultural source reports major pest or disease trouble. Still, NC State warns that garden cultivation can be difficult. PFAF lists no known food uses. It reports that the plant may poison cattle and sheep. That report does not establish safety for people or pets. PFAF also records past use of an infusion for diarrhoea. This historical use does not establish a safe treatment.