Disk water hyssop

Description

Bacopa rotundifolia is a species of water hyssop known as the disk water hyssop or round-leafed water hyssop, due to the shape of its leaves. This is an aquatic plant native to water bodies of the central United States and well known in other areas as an invasive weed of waterways. The round leaves are 1 to 3 centimeters wide and each has six longitudinal veins. The plant produces yellow-throated white flowers. The plant is in bloom during the fall, its fruit/seed abundance is medium and its seed spread rate is slow. The plant has no commercial use. 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 ponds in warmer climates. Most are easy to grow and will tolerate a wide range of conditions. B. monnieri will tolerate brackish water up to 15 ppt, due to specialized adaptations that enable it to survive in saline environments. Algal infestation can be a problem in brighter lighting conditions.