An annual, smooth herb with very slender stems, 6 to 24 inches high, and narrow, flat leaves one-half to 11/4 inches long which become blackened in drying. Stem branched, especially above, the branches spreading or ascending. Flowers light purple and spotted, one-half to three-fourths of an inch long, on slender stalks longer than the corollas, from the axils of the upper reduced leaves of the stem and branches; corolla funnelform, vertically flattened and slightly two-lipped, the margin with five rounded lobes, smooth within. Fruit a small globular capsule, one-sixth to one-seventh of an inch in diameter, and longer than the calyx.
Memoir 15 N. Y. State Museum
Slender Gerardia - Agalini is tenuifalia
The Seaside or Salt-marsh Gerardia (Agalinis maritima Rafinesque) is rarely over a foot high, smooth and fleshy, with linear leaves and small, purple flowers, one-half to two-thirds of an inch long. Common in salt marshes along the coast. Another species (Agalinis acuta Pennell), of sandy fields and depressions of the coastal plain, has stems 1 to 2 feet tall and branched like A . purpurea, but the flowers are somewhat smaller, light purple or rose-purple, and each of the five lobes of the corolla indented.