Marsilea minuta, or dwarf waterclover is a species of aquatic fern in the family Marsileaceae. It is not to be confused with Marsilea minuta E.Fourn. 1880, which is a synonym for Marsilea vestita.[1] Other common names include gelid waterklawer, small water clover, airy pepperwort, and pepperwort,[2] though the lattermost also applies to plants in the genus Lepidium. In French it is calledFrench: marsilea à quatre feuilles (literally "four-leafed marsilea") and French: petite marsilée (literally "little Marsilea"), the latter appearing to be a calque with the Latin botanical name. In Chinese it is Chinese: 南国田字草,[3] literally "southern field word grass," referencing the similarity of the leaflet shape to the Chinese character for "field." The Koch Rajbongshi people and Garo people call it shusni shak.[4] It is called 'Bengali: শুশনি শাক' ('shushni shak') in Bengali. In parts of India it can be called Undetermined: sunisanakka[5] In Indonesian it is Indonesian: semanggi (literally "clover"), but this name also applies to Marsilea crenata. In Japanese it is and in Thai it is . In Malaysian it is tapak itik (literally "duck footprints"). In the Philippines it is Undetermined: kaya-kayapuan (literally "so crowded").
M. minuta has a variable appearance, which often leads to confusion with closely related species. In the water the plant is creeping and spreading, while on land it can appear cushion-like. It typically is perennial but sometimes appears annual. It is a tenagophyte, with the juvenile growing submerged and the adult typically terrestrial.
It has a light brown to green rhizome that is NaNmm thick with short tan hairs at the ends and internodal roots. The land leaves are on erect, terete, NaNcm (-2,147,483,648inches) long petioles. The leaflets are NaNcm (-2,147,483,648inches) by NaNcm (-2,147,483,648inches), mostly glabrous, cuneate or flabellate. The leaves in water are typically not floating, but emergent from the water. Fertile leaves are produced on land with up to four sporocarps each at penduncles near the base of the petiole. It has a small sporocarp that is NaNmm long, NaNmm wide, and NaNmm thick.[6] The sporocarp has a superior tooth at the apex of the stalk and an inferior tooth at the base.[7] The sporocarp has a conspicuous NaNmm long raphe, about ⅔ the length of the sporocarp and semi-terete. Unlike a few Marsilea species, M. minuta sporocarps mature above ground.
| Ploidy: | diploid[8] |
| Chromosomes: | 40 |
M. minuta is thought to be closely related to Marsilea quadrifolia. Molecular phylogenetic analysis of the genus Marsilea puts both in a widespread Old World subgroup also called "Marsilea" along with M. angustifolia, M. drummondii, M. crenata, and M. fadeniana and indicating that M. crenata is actually a synonym of M. minuta.