About Marsilea minuta L.
Marsilea minuta L. has a variable appearance, which often leads to confusion with closely related species. When growing in water, the plant is creeping and spreading, while when growing on land it can form a cushion-like shape. It is typically a perennial plant, but sometimes behaves as an annual. It is a tenagophyte, with juvenile individuals growing submerged, and adult individuals typically growing on land. Its rhizome ranges in color from light brown to green, is 0.4–0.8 millimetres thick, has short tan hairs at the ends, and grows roots at internodes. Land-growing leaves are borne on erect, terete petioles that are 5–13 centimetres long. Its leaflets measure 0.8–1.7 centimetres by 1.2–2 centimetres, are mostly glabrous, and are shaped cuneate or flabellate. Water-growing leaves do not typically float, but instead emerge from the water. Fertile leaves are produced on land, with each holding up to four sporocarps on peduncles near the base of the petiole. Its sporocarps are small, measuring 2.6–4.1 millimetres long, 2.4–3.1 millimetres wide, and 1.3–1.7 millimetres thick. Each sporocarp has a superior tooth at the apex of the stalk and an inferior tooth at the base. It also has a conspicuous 1.5–2.2 millimetre long raphe, which is about two-thirds the length of the sporocarp and semi-terete. Unlike some other Marsilea species, M. minuta sporocarps mature above ground. Marsilea minuta grows at elevations from sea level up to 1,950 m, in ponds and other shallow water. It can grow in fresh or brackish water, in either clay or sandy soil. The plant can form large colonies and can be weedy. While some of its preferred habitat is being lost to conversion for agriculture, the species readily grows in paddy fields, drainage ditches, and other marginal areas, so its overall population is stable. It has the potential to be invasive, so dispersal via the aquarium trade and other human-mediated pathways should be limited. The leaves and sporocarps of M. minuta are eaten by many waterfowl species; intact sporocarps pass through the digestive system undigested, and are spread to new locations this way. The moth Elophila responsalis also feeds on the leaves, but is not thought to cause significant damage to M. minuta plants. The species is susceptible to the herbicides bensulfuron-methyl, cinosulfuron, 2,4-dichlorophenoxyacetic acid, oxyfluorfen, and paraquat, but it can tolerate high levels of organic pollution. In terms of human use, M. minuta is eaten in India, Sri Lanka, and Bangladesh. In China it is used as forage for livestock. Its raw protein content is 3.3%. The plant is used in traditional Chinese medicine to treat edema, skin injuries, snakebite, and inflammation. In Mymensingh District, it is used in traditional medicine to treat cough, headache, hypertension, sleep disorders, and respiratory diseases. When combined with Nardostachys jatamansi, it was developed by Asima Chatterjee into an Ayurvedic epilepsy treatment called Ayush-56. However, Ayush-56 has not shown encouraging results for treating epilepsy. It is also used as a phytoremediator for arsenic when it is grown alongside rice plants.
