Lemon bacopa (Bacopa caroliniana) occurs throughout Florida and the states that comprise the Southeast Coastal Plain - Maryland to Texas. It is not found outside the U.S. as its close cousin, water hyssop (B. monnieri) is. It also is strictly a species of freshwater wetlands.
Lemon bacopa creeps across the ground (or shallow water) forming large mats in locations where its water needs are met. It is tolerant of full to partial sun. The lime green stems and nearly succulent leaves are indistinguishable from water hyssop, but they give off a pungent lemon fragrance when bruised. It tends to die back in the winter months and return again in early spring.
Lemon bacopa has bright lavender to nearly purple flowers with a deep purple throat, sometimes surrounded by a white ring. The flowers are produced over many months from late spring to late fall. Small pollinators use these blooms for nectar.
The flowers and the glossy fragrant foliage make this an extremely attractive landscape plant, but the foliage is not used by White Peacock butterflies. It is also a very difficult plant to maintain in the landscape as it requires more moisture than water hyssop and is very less forgiving of even short-term drought. Though not an easy plant to maintain in the ground (except at the edges of ponds and marshes), it can be effectively provided for in pots and makes a very interesting specimen in a hanging basket. Just keep it well watered. Lemon bacopa is rather widely propagated by commercial sources, but may take a bit of sleuthing to locate it.