This large genus of roughly seventy annual and herbaceous perennial species belongs to the figwort family (Orobanchaceae) and spans North America, Mexico, the Caribbean, and into Central and South America. The name combines the Greek aga, meaning remarkable, and the Latin linum, meaning flax — a reference to the plant's superficial resemblance to that slender annual. Many species are native to the United States, though habitat loss has made a significant number of them threatened in various states. Depending on species, they turn up in wet meadows, boggy shores, moist thickets, and even in drier open ground.

Most prefer full sun to partial shade in well-drained, moist soil, growing one to three feet tall and producing tubular flowers in shades of pink, purple, and white from late summer into fall. This is valuable real estate in the garden calendar, when pollinators are still active but options are thinning. Use them in native and pollinator gardens, along pond and stream edges, or grouped in a naturalized border for a wash of late color. Propagation is by seed. Because needs vary considerably between species, confirm the requirements of a specific Agalinis before planting.