Marsilea crenata (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Marsilea crenata C. Presl

Protologue: Reliq. haenk. 1: 84, t. 12, f. 13 (1825).

Family: Marsileaceae

Chromosome number: 2n= 40, (60)

Marsilea quadrifolia Blume non L. (1828), M. minuta Raciborski non L. (1898), M. elata A. Braun var. crenata (C. Presl) Sadeb. (1900).

• Water-clover fern, pepperwort (En)
• Indonesia: semanggi (Javanese), jukut calingcingan (Sundanese)
• Malaysia: tapak itek (Malay), nán kuó t'ién tzù ch'auo (Chinese)
• Philippines: upat-upat, kaya-kayapuan, banig-usa
• Cambodia: chutul phnom
• Laos: pak vaen
• Thailand: phak waen (northern, central), nuu-toh (northern), phak lin-pee (peninsular)
• Vietnam: rau bợ, cỏ chữ diền, rau dệu răng.

M. crenata is widely distributed throughout South-East Asia from Thailand to Hong Kong and from Taiwan to Australia.

In Indonesia (Java), the Philippines (Bukidnon) and Thailand the young leaves of M. crenata are cooked and eaten as a vegetable. They are eaten fresh in Thailand as a side dish with local hot and spicy dishes, and are also grazed by cattle when grass is scarce. In the Philippines M. crenata is applied medicinally for neurasthenia and oedema. In India it is used against leprosy, skin diseases, fever and blood poisoning. The large sporocarps of Australian species are ground into flour and eaten. M. crenata is also a popular aquarium plant and a potential aquatic garden plant. In many countries it is a noxious weed of irrigated rice.

M. crenata is used on a very small scale only and sometimes offered on local markets, but there is no international trade.

M. crenata is a source of potassium, calcium, iron, magnesium and crude protein. Nutrient analysis of M. crenata in Thailand revealed that per 100 g edible portion it contained: protein 1.0 g, fat 1.2 g, fibre 3.3 g, Ca 48 mg, Fe 25 mg, vitamin A 12166 IU, vitamin C 3 mg. The energy value was about 63 kJ. An analysis in the Philippines revealed that young, unexpanded fronds of M. crenata contained on dry-weight basis: crude protein 3.7%, K 0.2% , Ca 0.4%, Fe 1.7% and Mg 7.2%. The sporocarps are rich in thiaminase which breaks down vitamin B1, and a prolonged diet may cause poisoning. When fed to gerbils, the related palaeotropical M. minuta L. had a cholesterol and trigliceride lowering effect, prevented the accumulation of cholesterol and triglicerides in the liver and aorta, and was able to dissolve atheromatous plaques of thoracic and abdominal aorta. Faecal excretions of cholesterol and triglycerides were significantly increased. When tested for its nutritious value, the widespread M. quadrifolia L. exhibited wide fluctuations between seasons and was not very promising in nutrient composition compared to other commonly used green leafy vegetables.

A small, creeping fern with erect leaves much resembling four-leaf clover. Rhizome long-creeping, irregularly branched, rooting at the nodes, of few mm in diameter and indefinite length, with pale brown hairs; the nodes 3-5 cm apart when submerged, much closer when terrestrial. Leaves arising from the nodes of the rhizome, solitary or clustered; petiole 2-4 cm long on terrestrial plants, 6-30 cm long on aquatic plants, pale to green, darker towards the base, glabrous or sparsely scaly; lamina symmetrical quadrifoliate with the four leaflets broadly obovate, flabellate, 3-25 mm × 2-23 mm, base cuneate, distal margin entire, subentire or sinuate, apex rounded, thin, coriaceous, glabrescent or hairy; veins anastomosing with narrow areoles without included veinlets. Sporocarp oblong, 3-4 mm long, stalk 1-5 mm long, attached to the base of the petiole, apex rounded with 2 small teeth, not ribbed, covered with caducous hairs, with the entire base perpendicularly attached to the stalk, solitary or in groups of 2-5; sporangia of 2 different kinds, one kind producing smaller spores (microspores) which give rise to prothalli bearing only male gametes, the other kind producing much larger spores (megaspores) which develop into prothalli producing only female gametes.

M. crenata has long and slender rhizomes during the growing season when grown in flooded rice fields. The rhizomes are submerged and root in the mud. When the fields dry up, the rhizomes become short-creeping and produce much smaller leaves closer together. The length of the petioles depends on water depth. When water level is low, the leaves protrude above the water surface, when the water is deep the leaflets float. The leaves respond well to light intensity and direction. During the day the leaflets lie in a plane to catch a maximum of radiation, while at night they fold together.

Sporocarps open only in water, splitting along their ventral sides and apices, the edges spreading, exposing many sori. A mucilaginous ring surrounding a sorus expands as water enters. The spores are set free by dissolution of the indusium and sporangial wall and will germinate only under suitable conditions. M. crenata needs abundant water to grow vegetatively. It multiplies rapidly under favourable conditions and often becomes noxious.

M. crenata , like the entire genus Marsilea L. with 60-70 species, has a history of ample synonymy and homonyms due to misidentifications. The genus is "sorely in need of a revision". M. crenata as treated here is not well defined and might either refer to a species complex or be conspecific with plants presently known by another specific name. The leaves of M. crenata at first glance resemble the foliage of Oxalis corniculata L. of the family Oxalidaceae , but bears 4 leaflets at the end of the slender petiole. Inspection of the creeping rhizome of Marsilea easily removes any doubts. M. crenata is related to M. polycarpa Hook. et Grev. in Peninsular Malaysia which has many sporocarps attached 3-5 cm above the petiole base.

M. crenata grows in muddy soils with stagnant water, in ditches, shallow pools and in rice fields, from lowland up to 900 m altitude. It tolerates polluted fresh water. The sporocarps are very persistent and can keep spores viable for many years, which is an important trait in environments that periodically dry up. The spores can also pass undamaged through the digestive tract of water birds.

Propagation of M. crenata is by spores, rhizome cuttings or plantlets separated from rhizomes. Under natural circumstances spores spread and germinate in muddy media. In Thailand, for vegetative propagation, 4-5 rhizome parts about 5 cm long and with 2-3 buds are tied together to a pole and planted 1 m apart in swampy areas.

M. crenata has been commercially grown locally in Thailand, in ditches with a water level of about 30 cm depth and without shade along roads in the vicinity of urban areas.

In Thailand, the snail Pomacea canaliculata may cause serious damage to M. crenata .

M. crenata is harvested from the wild at the beginning of the rainy season. When cultivated, the first young, full-grown leaves can be harvested 3 months after planting. The leaves are cleaned thoroughly and sold tied in bundles.

Due to its wide distribution, rapid growth and low exploitation, it seems that M. crenata is not in immediate danger of genetic erosion. However, due to changing cultivation practices in rice cropping, it has rapidly declined in many areas during the last decade. Germplasm collections and breeding programmes are not known to exist.

M. crenata grows easily in ditches, shallow ponds and swamps, and even tolerates polluted fresh water. As it has no specific flavour, it has the potential to be widely accepted. Efforts to cultivate M. crenata should be encouraged by making use of neglected water areas to produce greens. The medicinal cholesterol-lowering properties of Marsilea are promising and should be further explored.

• Amoroso, V.B., 1990. Ten edible economic ferns of Mindanao. The Philippine Journal of Science 119(4): 295-313.
• Backer, C.A. & Posthumus, O., 1939. Varenflora voor Java [Fern flora of Java]. 's Lands Plantentuin, Buitenzorg, Dutch East Indies. pp. 263-264.
• Holttum, R.E., 1966. A revised Flora of Malaya. 2nd Edition. Vol. 2. Ferns of Malaya. Government Printing Office, Singapore. pp. 619-620.
• Maranon, J., 1935. Nutritive value of Philippine food plants (calcium, phosphorus and iron contents). Philippine Journal of Science 58: 317-358.
• Ochse, J.J. & Bakhuizen van den Brink, R.C., 1980. Vegetables of the Dutch East Indies. 3rd English edition (translation of "Indische groenten", 1931). Asher & Co., Amsterdam, The Netherlands. pp. 481-483.
• Thiraphon, S., 1993. Pluk phakwaen rim thang [Commercial planting of Marsilea crenata]. Kasikon 66(4): 35-36.

J.J. Afriastini