Monochoria vaginalis (pickerel weed)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Host Plants and Other Plants Affected
- Biology and Ecology
- Notes on Natural Enemies
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Monochoria vaginalis (Burm.f) C.Presl. (1827)
Preferred Common Name
- pickerel weed
Other Scientific Names
- Gomphima vaginalis Rafin. (1836)
- Monochoria junghuhniana Hassk. (1852)
- Monochoria linearis Miq. (1859)
- Monochoria ovata Kunth (1843)
- Monochoria pauciflora Kunth (1843)
- Monochoria plantaginea Kunth (1843)
- Pontederia linearis Hassk. (1842)
- Pontederia pauciflora Bl. (1827)
- Pontederia plantaginea Roxb. (1832)
- Pontederia vaginalis Burm. F. (1768)
International Common Names
- Spanish: monocoria
Local Common Names
- Bangladesh: Panee kachu
- Cambodia: Chrach
- Indonesia: Etjeng padi
- Indonesia/Java: Bengok
- Japan: Konagi
- Korea, DPR: Mooldalgebi
- Malaysia/Peninsular Malaysia: Chacha layar; Keladi agas; kelayar
- Nepal: Piralay
- Philippines: Biga-bigaan; Gabi-gabi
- Taiwan: Ya-she-tsau
- Thailand: Ka-kiad; Phak-khait
- Vietnam: Rac mác lá thon
- MOOVA (Monochoria vaginalis)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Monocotyledonae
- Order: Pontederiales
- Family: Pontederiaceae
- Genus: Monochoria
- Species: Monochoria vaginalis
Notes on Taxonomy and NomenclatureTop of page M. vaginalis is very variable and for this reason may be misidentified. Backer and Bakhuizen van den Brink Jr (1968) note that "Specimens with few-flowered inflorescences and small, often narrow, proportionally long leaves have wrongly been described as varieties or even separate species. They are either young or weak, or were collected in deep water".
Three varieties of M. vaginalis (Burm. F.) C. Presl. (1827) have been recognized (Gopal, 1987): var. minor Miq. (1859); var. plantaginea (Roxb.) Solms. (1883); and var. pauciflora (Bl.) Merr. (1917).
A variety of M. vaginalis was described by Ohwi (1965) as M. vaginalis (Burm. F.) Presl var. plantaginea Roxb. Solms-Laub (= Pontederia plantaginea Roxb. and Monochoria plantaginea Roxb. Kunth.). This has been recorded in Japan, Korea and China (Holm et al., 1977) and is described as having long-petioled basal leaves, shorter petioles on leaves attached to a stem or axis, a (3-7)-flowered inflorescence and purplish-blue flowers.
M. vaginalis is occasionally cited as a native of tropical Africa, as well as Asia (e.g. Holm et al., 1977). However, in the Flora of West Tropical Africa (Hutchinson et al., 1968), earlier references to M. vaginalis var. plantaginea in the region are concluded to be erroneous and instead are re-categorized as M. brevepetiolata.
Patwary et al. (1989) suggest interspecific hybridization between Monochoria vaginalis and Monochoria hastata Solms. in populations grown in Bangladesh. They identified two distinct morphological types of each species and from morphological and cytological observations suggested that M. vaginalis type II (2n = 52) is an allotetraploid derived from M. hastata type I (2n = 28) X M. vaginalis type I (2n = 24). They also suggest that M. hastata type II (2n = 80) is an autoallohexaploid hybrid of M. vaginalis type II X M. hastata type I.
DescriptionTop of page M. vaginalis is a fleshy, tufted, annual or perennial herb with a glabrous, shiny appearance and a short rhizome. It is an aquatic herb, forming rosettes and spreading by short stolons.
It is 10-50 cm tall and stemless. Older plants often form large clumps, but these are not connected. Leaf size and shape is highly variable. In young plants without lamina, the leaves are 2-12.5 cm long and 0.5-10 cm wide. In somewhat older plants, the leaves are floating, linear or lanceolate and in still older plants, are ovate-oblong to broadly ovate, sharply acuminate with a heart-shaped or rounded base, shiny, deep-green, and with longitudinal veins. The petioles are soft and hollow, usually less than 30 cm in length and growing from buds at the base; leaf sheaths are twisted together at the base and slightly reddish when young.
The inflorescence is spicate, 3-6 cm long, basally opposite the sheath of the floral leaf with a large bract arising from a thickened bundle on the leaf stalk, about two-thirds of the way up the stalk from the base. The flowers are pedicelled, bisexual, choripetalous, in racemes, initially inside the sheath of the apical leaf and recurved after anthesis. Flowers number from 3-25 and open simultaneously or from top to bottom in quick succession, with six violet or lilac petals which are spreading at flowering and later spirally contorted. Pedicels are 4-25 mm long and the perianth 11-15 mm long. The stamens are six in number, one with a lateral, obliquely erect tooth. The ovary has a long style, and the capsule (of about 1 cm in size) splits between the partitions into three valves. Seeds are numerous and longitudinally ribbed. (After Holm et al, 1977; Pancho and Soerjani, 1978; Soerjani et al., 1987.)
The distinguishing characteristics of M. vaginalis are the spike-like inflorescence opposite the floral leaf, and the one stamen with a lateral, oblique, erect tooth.
DistributionTop of page The geographical distribution of M. vaginalis shown in the map is incomplete. This species has been recorded in Korea and Japan, through the Pacific Islands (including Hawaii), to the mainland of South-East Asia and across into India (Holm et al., 1977). However, specific references to some locations (for example, the individual Pacific Islands) were not found and therefore are not included in the map.
Similarly, few detailed references were found on its distribution within individual countries, though its occurrence is acknowledged to be widespread. For example, M. vaginalis is said to occur throughout Indonesia (Soerjani et al., 1987); at a wide range of altitudes and probably in all districts of Bhutan (Parker, 1992); throughout India, from Kashmir to Assam (Kaul, 1986) and in East, Central and South China, as well as Hebei, Shaanxi, Gansu, Sichuan, Guizhow and Yunnan provinces (Wang, 1990).
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Brunei Darussalam||Present||IRRI, 1989|
|-Hong Kong||Present||Holm et al., 1979|
|-Jiangsu||Present||Jiang et al., 1989|
|-Assam||Widespread||Deka and Phookan, 1992|
|-Jammu and Kashmir||Present||Kaul, 1986|
|Indonesia||Widespread||Soerjani et al., 1987|
|-Java||Present||Burhan et al., 1989|
|Iran||Restricted distribution||Sharifi, 1990|
|Japan||Widespread||Pancho and Soerjani, 1978|
|Korea, DPR||Present||Holm et al., 1979|
|Korea, Republic of||Present||Holm et al., 1979|
|Malaysia||Present||Holm et al., 1979|
|-Peninsular Malaysia||Present||Burkill, 1935|
|-Sarawak||Widespread||Holm et al., 1977|
|Nepal||Present||Ranjit and Bhattarai, 1988|
|Philippines||Present||Moody et al., 1984|
|Singapore||Present||Pancho and Soerjani, 1978|
|Sri Lanka||Present||IRRI, 1989|
|Taiwan||Present||Holm et al., 1979|
|USA||Restricted distribution||Holm et al., 1977|
|-Hawaii||Present||Holm et al., 1977|
HabitatTop of page A native of Asia, M. vaginalis is a plant of subaquatic to aquatic conditions (Ampong-Nyarko and De Datta, 1991) and is locally abundant (Pancho and Soerjani, 1978). It can occur in areas with a pronounced dry season, and is typically found in sunny sites in swamps, marshes, open wet places, along ditches and in all types of inundated rice (Soerjani et al., 1987). In Java it occurs from 0-700 m elevation in freshwater pools, mudflats in rivers, ditches, ricefields, and along canal banks (Backer and Bakhuizen van den Brink Jr, 1968). In Fiji it grows in shallow water, swampy ground, open drains, ricefields, or in very wet soils (Parham, 1958).
With the exception of its recorded incidence in taro in Hawaii, all references to its occurring as a weed concern paddy rice in tropical Asia and the Pacific Islands (Holm et al., 1977).
Host Plants and Other Plants AffectedTop of page
|Oryza sativa (rice)||Poaceae||Main|
Biology and EcologyTop of page Relatively little is known of the biology of M. vaginalis (Holm et al., 1977).
M. vaginalis may be an annual in flooded ricefields, but can also grow as a perennial in constantly flooded conditions (Holm et al., 1977). The plant roots in mud, with its upper portions growing above the water. Reproduction is mainly from seed, with occasional new growth from tubers (Pancho and Soerjani, 1978). Flowering can occur throughout the year in the Philippines (Merrill, 1912). M. vaginalis is characterized by prolific seed production: Gupta (1968) suggested that submergence of the fruits after pollination was beneficial for seed development.
Noda and Eguchi (1965) found that seedling emergence is greater in early planted ricefields in Japan and, with early planting, seedling emergence was higher in saturated soils than in dry soils. They also found that the patterns of seed germination varied greatly according to moisture levels. In submerged conditions, the majority of seedlings emerged within a short space of time, the peak germination being between 15 and 25 days. In contrast, in saturated or dried soils, germination occurred gradually throughout the season. Miyahara et al. (1989) studied seedling emergence from buried seed over a 15-year period and found that emergence declined from one year to the next more rapidly in well-drained than in poorly drained soils. Kim and Mercado (1987) suggest that M. vaginalis seeds develop a light requirement for germination when buried for 1 month or longer at depths of greater than 1 cm.
M. vaginalis is a rapidly growing, competitive C3 plant (Ampong Nyarko and De Datta, 1991). Its property of discontinuous germination allows it to evade control.
In Taiwan M. vaginalis produced higher fresh-weight yields in paddy fields than any other weed species (Lin, 1968).
Notes on Natural EnemiesTop of page Waterhouse (1994) has summarized records of natural enemies attacking M. vaginalis in South-East Asia. All are polyphagous, but because M. vaginalis is apparently not a weed in Africa or western Asia, it would be worthwhile to investigate its natural enemies in these areas.
ImpactTop of page M. vaginalis is a serious weed in ricefields in east and southern Asia. It is a principal weed of rice in Korea, Malaysia (Sarawak) and the Philippines. It is one of the three most serious weeds of rice in Indonesia, Japan and Taiwan and is a common weed of rice in Cambodia, Sri Lanka, China, India and Thailand (Holm et al., 1977). In Bhutan, it is a major weed of flooded rice, often the most abundant and dominant species and regarded as one of the most important by farmers (Parker, 1992).
With the exception of its recorded incidence in taro in Hawaii, all references to its occurring as a weed concern flooded rice in tropical Asia and the Pacific Islands (Holm et al., 1977). It occurs in all types of rice (except dryland rice) including transplanted, both wet and dry direct-seeded and in deepwater and tidal swamp rice (IRRI, 1989).
M. vaginalis is a rapidly growing, competitive C3 plant (Ampong Nyarko and De Datta, 1991). Its property of discontinuous germination allows it to evade control.
Sattar and Biswas (1991) recorded yield losses in rice of up to 82% at high densities of M. vaginalis. In competition studies in the Philippines, M. vaginalis was less competitive with rice than the other principal weed, the annual grass Echinochloa crus-galli (Lubigan and Vega, 1971). The critical weed population was 60 plants per square metre: a natural stand of 366 plants per square metre reduced rice yield by 35%. Lubigan and Vega (1971) concluded that M. vaginalis does not compete seriously for light and, being shallow rooted, the deeper-rooted rice plants are able to compete more vigorously for nutrients.
M. is reported to be a secondary host for the rice grassy stunt virus, transmitted by the brown planthopper, Nilaparvata lugens (IRRI, 1988) and for Sarocladium oryzae (Deka and Phookan, 1992). It is also a host of rice ragged stunt oryzavirus (RRSV) (Salamat et al., 1987), though it may not act as a reservoir of this virus (Parejarearn et al., 1988).
All parts of M. vaginalis except for the roots are relished as a vegetable (Mabberley, 1990) and it is used locally as a medicine (Burkill, 1935; Mabberley, 1990). The roots are used against stomach and liver ailments and against toothache (Soerjani et al., 1987). It is also used as cattle fodder (Patwary et al., 1989).
Uses ListTop of page
Human food and beverage
Similarities to Other Species/ConditionsTop of page M. vaginalis is similar in appearance to a related species M. hastata: the latter plant is larger and has a well-developed, branched rhizome, whereas M. vaginalis has a short rhizome. M. hastata has predominantly sagittate or hastate leaves whereas the leaves of M. vaginalis are heart shaped. M. hastata has more flowers in the raceme and, although the flowers of M. vaginalis open nearly simultaneously, those of M. hastata do not. The lower pedicels of flowers on M. hastata are elongated, whereas all pedicels in M. vaginalis are less than 1 cm long. (Holm et al. 1977).
The more serious weed, Eichhornia crassipes (water hyacinth) is in the same family as M. vaginalis and bears some resemblance. Eichhornia crassipes differs in being more robust (up to 1 m tall), with larger and more numerous flowers which are borne on a separate stalk, rather than appearing laterally on leaves. Eichhornia crassipes occurs as a free-floating aquatic plant on lakes and ponds.
Prevention and ControlTop of page Seed germination and seedling growth of M. vaginalis are encouraged by submergence and in rice this weed is therefore not controlled by irrigation. It is not difficult to remove by hand, but requires persistence to remove successive flushes of germination (Parker, 1992).
The pattern of seed germination varies according to moisture levels (Noda and Eguchi, 1965). In submerged conditions, the majority of seedlings emerge within a short space of time, with a germination peak 15-25 days after shedding. Under these circumstances, a single weeding or herbicide treatment after the germination flush could give season-long control. In saturated or dry soils, however, germination can occur throughout the season, so that a single weeding would be less effective and season-long control would be required.
In a study in the Philippines, Krock et al. (1988) found that mats of the aquatic fern Azolla used to suppress weeds in rice were particularly effective for the control of M. vaginalis.
This weed is usually controlled by butachlor, but requires a full dose of the herbicide (Parker, 1992). Other herbicides to which it is sensitive include bensulfuron, bentazone, butralin, chlomethoxyfen, cinmethylin, 2,4-D, glyphosate, MCPA, oxadiazon, oxyfluorfen, paraquat, pendimethalin, piperophos and pretilachlor. It is most sensitive to quinclorac and thiobencarb, but resistant to fenoxaprop (Ampong-Nyarko and De Datta, 1991), and propanil rarely gives good results (Soerjani et al., 1987). In greenhouse trials, it was highly susceptible to pyributicarb (Tsukuda et al., 1993).
ReferencesTop of page
Backer C; Bakhuizen van den Brink R, 1968. Flora of Java, Volume 3. Groningen: Wolters-Noordhoff NV.
Burhan H; Sozzi D; Zoschke A, 1989. Setoff for weed control in rice: practical experience from Indonesia. Proceedings, 12th Asian-Pacific Weed Science Society Conference Taipei, Taiwan; Asian-Pacific Weed Science Society, No. 1:127-131
Burkill IH, 1935. A Dictionary of the Economic Products of the Malay Peninsula, Volumes 1 and 2. London, UK: Governments of the Straits Settlements and Federal Malay States, Crown Agents for the Colonies.
Gupta S, 1968. Flowering process and curvature behaviour of the inflorescence in Monochoria vaginalis Presl. Tropical Ecology, 9:234-238.
Hutchinson J; Dalziel JM, 1968. Flora of West Tropical Africa, 2nd edn. Millbank, London: Crown Agents for Overseas Governments and Administrators.
IRRI, 1988. Annual Report for 1987. Los Ba±os, Philippines: International Rice Research Institute.
IRRI, 1989. Weeds Reported in Rice in South and South East Asia. Manila, Philippines: International Rice Research Institute.
Kim JS; Mercado BL, 1987. Viability and emergence of buried seeds of Echinochloa glabrescens, Monochoria vaginalis and Cyperus difformis. Proceedings, 11th Asian Pacific Weed Science Society Conference Taipei, Taiwan; Asian Pacific Weed Science Society, No. 2:469-476
Lin C, 1968. Weeds found on cultivated land in Taiwan. Volumes 1 and 2. Taipei, Taiwan: College of Agriculture, National Taiwan University.
Lubigan R; Vega M, 1971. The effect of different densities and durations of competition of Echinochloa crusgalli (L.) Beauv. and Monochoria vaginalis (Burm. f.) Presl. on the yield of lowland rice. Weed Science Report 1970-71. Los Ba±os, Philippines: University of the Philippines, 19-23.
Mabberley DJ, 1990. The Plant Book: a Portable Dictionary of the Higher Plants. Cambridge, UK: Cambridge University Press.
Merrill E, 1912. A Flora of Manila. Publication 5. Manila, Philippines: Bureau of Science.
Miyahara M; Morita H; Takabayashi M, 1989. Survival of seeds of major annual weeds buried in cultivated soil for 15 years under different soil moisture conditions and cultivation types in paddy fields of Southern Japan. Proceedings, 12th Asian-Pacific Weed Science Society Conference Taipei, Taiwan; Asian-Pacific Weed Science Society, No. 1:57-66
Moody K; Lubigan RT; Munroe CE; Paller EC, 1984. Major weeds of the Philippines. Weed Science Society of the Philippines. Los Ba±os, Laguna, Philippines: University of the Philippines.
Noda K; Eguchi S, 1965. Studies on ecology of weeds on arable lands: 1. Emergence patterns of annual representative weeds which are commonly found on the paddy rice fields of south-western Japan. Bulletin of the Kyushu Agricultural Experimental Station, 11:153-170.
Ohwi J, 1965. Flora of Japan. Smithsonian Institution, Washington, DC, 418.
Pancho JV; Soerjani M, 1978. Aquatic weeds of Southeast Asia. A systematic account of common Southeast Asian aquatic weeds. Aquatic weeds of Southeast Asia. A systematic account of common Southeast Asian aquatic weeds., 130 pp.; [260 X 180 mm].
Parham J, 1958. The Weeds of Fiji. Bulletin 35. Suva, Fiji: Department of Agriculture.
Ranjit JD; Bhattarai AN, 1988. Crop Weeds and their Control in Nepal. Kathmandu, Nepal: Winrock International/USAID.
Tsukuda K; Murakami M; Morinaka H; Tsuzuki K; Ichizen N; Konnai M; Takematsu T, 1993. Herbicidal and phytotoxic properties of pyributicarb, a new paddy herbicide, and its movement in soil. Weed Research (Tokyo), 38(3):175-181
Wang Z, 1990. Farmland weeds in China: a collection of coloured illustrative plates. Beijing, China: Agricultural Publishing House.
Distribution MapsTop of page
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