Bacopa

Bacopa is a genus of 70–100 aquatic plants belonging to the family Plantaginaceae. It is commonly known as waterhyssop (or water hyssop, though this is more misleading as Bacopa is not very closely related to hyssop but simply has a somewhat similar appearance). They are annual or perennial, with decumbent or erect stems. The leaves are opposite or whorled, and sessile. The leaf blade is regular, round to linear, and the venation is palmate or pinnate. Its stems are hairy or smooth. The flowers are produced solitary or in pairs from leaf axils, usually radially symmetrical, with five sepals and five petals, and they are usually white, blue, or purple. Dispersal and propagation is by seeds and stem fragments. Crushed leaves have a distinctive 'lemon' scent. Bacopa species are found in tropical and subtropical regions of the world, particularly the Americas. A few are regarded as weeds and excess stock should not be dumped in warmer regions. Most grow in moist amphibious conditions, though some like B. myriophylloides seem to be wholly aquatic. Bacopa monnieri is used in Ayurvedic medicine. Preliminary clinical research found that the herb may improve cognition. Some of these species are commonly used in freshwater aquariums and around and in ponds in warmer climates. Most are easy to grow and are slow-growing, but require medium to high amounts of light. Most are easy to grow and will tolerate a wide range of water conditions. B. caroliniana at least will tolerate brackish water. Plants are usually best planted in groups in the middle to background. Algal infestation can be a problem in brighter lighting condition.