Agalinis purpurea var. parviflora
Stems 7–60 cm; branches ascending. Flowers: calyx tube 2–3.5 mm; corolla 9–20 mm, lobes projecting to spreading, 2.5–5(–6) mm; distal anthers included or exserted, oblique or perpendicular to filaments, pollen sacs 0.9–2 mm; style included or slightly exserted.
Phenology: Flowering Jul–Sep.
Habitat: Moist sandy, clay, or peaty soils at margins of ponds, lakes, streams, bogs, freshwater or brackish marshes, ditches, roadsides.
Elevation: 0–300 m.
Man., N.B., N.S., Ont., Que., Conn., Del., D.C., Ill., Ind., Iowa, Maine, Mass., Mich., Minn., N.H., N.J., N.Y., Ohio, Pa., R.I., Vt., Wis.
Plants of var. purpurea are shorter and less branched in the northernmost part of their range, and the flowers are not notably smaller. In the Great Lakes region, New England states, and neighboring areas of Canada, var. parviflora has smaller, narrower corollas with included stamens and style, and ascending branches. Length and form of the calyx lobes are of no value for differentiation of varieties within Agalinis purpurea.