CAUTION: webmd gives warnings against the ingestion of the closely related Bacopa monnieri, so I will list them here in case Bacopa caroliniana has similar effects. Avoid if you are brest-feeding, have a slow heart rate [bradycardia], gastrointestinal tract blockage, ulcers, lung conditions, thyroid disorders, urinary tract obstruction.
EDIBLE LEAVES: "Both species of Bacopa are considered edible and are used in salads and as a seasoning by those with adventurous palates."  Some websites, such as fishpondinfo.com, list it as a seasoning.  They have the scent and flavor of fresh limes.
- TEA: The leaf and flowering stem tea has the scent and flavor of limes. Although some of my wildcrafting friends dry this flowering herb for later use, I much prefer it when the leaves are used fresh. Crush one four inch stem well and pour boiling water onto it in a cup. Let sit for ten minutes – add some honey if you like… yummy!
HARVEST TIME: All year. Freezes may harm the leaves.
MEDICINAL USES: Seminoles used it as a cough medicine. Other tribes used it as “a sedative or treated respiratory ailments with it.” Daniel Austin, in Florida Ethnobotany, writes “the herbs have a number of chemicals including brahmine and bacco-side A (Hocking 1994). These compounds have been used as nerve tonics in mental disorders, against psychosis, and for epilepsy (Hindus).”
NATIVE TO: The southeastern US, Maryland, south to Texas to Florida. Within Florida, it occurs in most, if not all, counties.
HABITAT: Freshwater wet places, wetlands, wet ditches, marshes, swamps, pond edges, sometimes [rarely in my experience] along the edges of slightly brackish water. Tolerates periods of submersion. It does not tolerate flooding by brackish water well.  Found "along shorelines" or "in water less than three feet deep." 
DESCRIPTION: An herbaceous, aquatic, short lived perennial  that sprawls along the ground, rising to 6 inches tall.  Width: "Extensive mats."  It lives, submerged, for periods of time as well.
- PHENOLOGY: Winter dormant. 
- STEMS: Succulent stems (and leaves creep to 12 inches, usually 3 – 6 inches tall. Stems hairy, sort of velvety, on the upper part. Submerged stems may grow to 3' long, and there have been reports of 12 feet long. 
- LEAVES: Opposite, hairy/rough, almost round, thick, succulent. Small, less than 3/4 of an inch.
- SCENT: The crushed leaves and stems have the scent of fresh pressed limes, not the often-listed scent of lemons, as most writers claim. The University of Florida describes it as having a "fragrance reminiscent of lemon, lime, anise, or licorice."  I wouldn't go that far, and would simply describe it a lime-like.
- FLOWERS: Blue, showy, five (sometimes 4 or 6) petals, fragrant, occasionally flowering below water (“though they soon rot.”).
- FRUIT: An inconspicuous capsule. 
WILDLIFE: It provides "habitat in wetland enhancement and restoration projects." 
- BUTTERFLIES: This plant is the host for the White Peacock Butterfly.
BIOLUMINESCENCE: “When gold nanoparticles were introduced into Bacopacaroliniana plants they caused the chlorophyll to produce reddish light. While lit, the glowing plants' vegetation consumed more carbon from the atmosphere than normal (i.e. the luminescence causes the cells to undergo photosynthesis). The Taiwanese research team behind the discovery hopes to implement modified Bacopacaroliniana plants as environmentally friendly street lamps. Popular Science calls this a "triple threat," in that the "trees" could cut energy costs, reduce global warming and keep streets safely lit at night.”
POTPOURII: The dried and chopped whole plant is added to potpouriis when a lime scent is desired.
AQUATIC GARDENS: "An attractive native addition to water gardens, aquascapes, and restoration and mitigation projects." 
AQUARIUM & WATER PLANT: This plant is used in the aquarium trade and is planted in water gardens.
ETYMOLOGY: Green Deane writes, “Bacopa is the latinized name the aboriginal Indians called it in what is now French Guiana." 
FAMILY CLASSIFICATION: This species has formerly been classified as being within the Figwort family, Scrophulariaceae. Currently, sources such as the Atlas of Florida Vascular Plants, the Florida Native Plant Society, and theplantlist.org, place it within the Plantain family, Plantaginaceae. The USDA, however, places it within Scrophularuaceae.
RELATED SPECIES: Bacopa monnieri, the Herb of Grace (known in India as Brahmi), also grows wild across Florida. It has white flowers, no lime scent, and is much more common. It has been used for thousands of years in Ayurvedic medicine to help with memory and such.
- HARDINESS: USDA zones 6 - 9.  I observe it growing across zone 10 here in Florida.
- SOIL: Regional Conservation writes, "it prefers soils with organic content, but will still grow reasonably well in nutrient poor soils." 
- PROPAGATION: By tip cuttings, 3-5" long , which are quite easy. There is no "need for rooting hormones."  Also by division. 
Wet Ditches, Pond Edges
When to Harvest
Sources for acquiring
A number of native plant nurseries statewide carry this species. The University of Florida writes, "Lemon Bacopa is widely available from a variety of sources, including stores that carry aquarium plants, water garden supply shops, and nurseries that sell aquatic or native plants."
 Florida Ethnobotany
 fnps.org [Florida Native Plant Society]
 Regional Conservation