Bacopa caroliniana aka Blue Water Hyssop

Bacopa caroliniana is known as lemon bacopa. It creeps along the ground and lives for years. It belongs to Plantaginaceae, the plantain family. It is native to the southeastern United States, Texas, and Cuba. It grows on shores, in marshes, and in disturbed wetlands. This wetland plant grows above or below water. In warm tropical areas, it stays green all year.

Garden plants reach about 0.3–1 foot [0.1–0.3 metres] tall. They spread about 1.7–3.3 feet [0.5–1 metre] wide. Stems may trail several feet across wet ground. Stems under water tend to reach 3 feet [0.9 metres] long. Reports note lengths of up to 12 feet [3.7 metres]. These extremes occur in deep, clear water. Green stems above water bear fine hairs. Stems below water have few hairs or none. The small, thick leaves grow in opposite pairs. Their edges are smooth. Shapes range from round to oblanceolate, or wider near the tip. Crushed leaves give off a scent like lemon. Some people smell lime, anise, or licorice instead.

Small blue flowers bloom from May through September. Each grows alone and forms a shallow cup. Each has five petals and measures under one inch across. They draw small pollinators, which help flowers set seed. The bloom season lasts a long time. Small, plain seed capsules follow from July through October. The young of white peacock butterflies feed on the plant. Its flowers and leaves give it value in wildlife gardens.

Grow lemon bacopa in moist or wet soil, or under water. It suits pond edges, bogs, rain gardens, and aquariums. NC State lists sandy or loamy soils. It gives a soil pH range from acidic to neutral. The plant accepts full sun. That source favors part shade outdoors. Plants grown indoors need bright light. It stands heat but not drought or salt. Sources differ on hardiness. NC State lists USDA zones 8–11. UF/IFAS gives zones 6–9 and notes winter dieback above water. Cuttings from stem tips root well without added rooting hormones. Keep their soil wet; dry soil can kill them.

The creeping growth suits ground cover, groups, and mass planting. It also suits hanging pots indoors and work to restore wetlands. NC State reports no major pest or disease problems. UF/IFAS warns that growth under water can become weedy. It can also be hard to control. Take cut plants off the site to help prevent their return. The supplied evidence does not show whether humans can eat it. Nor does it establish whether the plant is toxic.