''Persicaria odorata'', with common names Vietnamese coriander, rau răm,
laksa
Laksa is a spicy noodle dish popular in Southeast Asia. Laksa consists of various types of noodles, most commonly thick rice noodles, with toppings such as chicken, prawn or fish. Most variations of laksa are prepared with a rich and spicy coco ...
leaf,
Vietnamese cilantro, phak phai, praew leaf, hot mint and Cambodian mint,
is an herb with aromatic leaves, used in Southeast Asian and Northeast Indian cooking. The smell and taste are very similar to (but milder than) that of
cilantro/coriander leaf — not that of coriander powder, the plant’s ground seed — making the plant a useful alternative for some individuals’ palates.
Vietnamese coriander is not related to the
mints
A mint or breath mint is a food item often consumed as an after-meal refreshment or before business and social engagements to improve breath odor. Mints are commonly believed to soothe the stomach given their association with natural byproducts ...
, nor is it in the mint family
Lamiaceae
The Lamiaceae ( )
or Labiatae are a family of flowering plants commonly known as the mint, deadnettle or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil, mint, rosemary, sage, savory ...
, but its general appearance, growth habit and fragrance are somewhat reminiscent of them. ''Persicaria'' is in the family
Polygonaceae
The Polygonaceae are a family of flowering plants known informally as the knotweed family or smartweed—buckwheat family in the United States. The name is based on the genus ''Polygonum'', and was first used by Antoine Laurent de Jussieu in 1789 ...
, collectively known as the “knotweeds”, as well as "smartweeds" or "pinkweeds".
Food uses
Primarily, the leaf is prominent within
Vietnamese cuisine
Vietnamese cuisine encompasses the foods and beverages of Vietnam. Meals feature a combination of five fundamental tastes ( vi, ngũ vị, links=no, label=none): sweet, salty, bitter, sour, and spicy. The distinctive nature of each dish reflec ...
, where it is commonly eaten fresh in salads (including
chicken salad
Chicken salad is any salad with chicken as a main ingredient. Other common ingredients may include mayonnaise, hard-boiled egg, celery, onion, pepper, pickles (or pickle relish) and a variety of mustards.
Description
In Canada and the United St ...
), and in raw ''
gỏi cuốn
''Gỏi cuốn'' or nem cuốn, salad roll, summer roll, fresh spring roll, spring roll, rice paper roll, is a Vietnamese dish traditionally consisting of pork, prawn, vegetables, ''bún'' (rice vermicelli), and other ingredients wrapped in Vietn ...
''. Additionally, it can be found in some soups such as ''
canh chua
''Canh chua'' (, ''sour soup'')The term ''canh'' refers to a clear broth with vegetables and often meat, and ''chua'' means "sour". or ''cá nấu'' ("cooked fish") is a Vietnamese sour soup indigenous to the Mekong Delta region of Southern ...
'' and ''bún thang'', and in stews such as fish ''
kho tộ''. It is also popularly eaten with ''
trứng vịt lộn'' (fertilized
duck
Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form t ...
egg
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...
).
However, in
Malaysia
Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...
,
Singapore
Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...
and
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
, the shredded leaf is an essential ingredient of the ever-popular ''
laksa
Laksa is a spicy noodle dish popular in Southeast Asia. Laksa consists of various types of noodles, most commonly thick rice noodles, with toppings such as chicken, prawn or fish. Most variations of laksa are prepared with a rich and spicy coco ...
'' (spicy noodle soup), so much so that the leaf is commonly referred to as "laksa leaf" (''daun laksa''). In Malaysia, where people commonly refer to the leaves as ''daun kesum'', it is used in the dishes ''
nasi kerabu
Nasi kerabu is a Malaysian cuisine rice dish, a type of '' nasi ulam'', in which blue-colored rice is eaten with dried fish or fried chicken, crackers, pickles and other salads. The blue color of the rice comes from the petals of ''Clitoria ter ...
'' and ''
asam pedas
Asam pedas ( Minangkabau: ''asam padeh''; "sour and spicy") is a Maritime Southeast Asian sour and spicy fish stew dish. Asam pedas is believed to come from Minangkabau cuisine of West Sumatra, Indonesia and has spread throughout to the islands o ...
''.
In the
cuisine of Cambodia
Cambodian cuisine is an umbrella term for the cuisines of all ethnic groups in Cambodia, whereas Khmer cuisine ( km, សិល្បៈធ្វើម្ហូបខ្មែរ; ) refers specifically to the more than thousand years old culin ...
, where the leaf is known as ( km, ជីរក្រសាំងទំហំ) ''chi krasang tomhom'', it is used in soups, stews, salads, and the Cambodian summer rolls, ''naem'' (ណែម).
In
Laos
Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist ...
and certain parts of
Thailand
Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...
, the leaf is eaten with raw or stir fried ground beef, called ''
larb
''Larb'' ( lo, ລາບ; th, ลาบ, , , also spelled ', ', ' or ') is a type of Lao meat salad that is the national dish of Laos, along with green papaya salad and sticky rice
Glutinous rice (''Oryza sativa var. glutinosa''; also ...
'' or ''”laab”'' ( lo, ລາບ).
The leaves are locally known as phak phai in
Manipur
Manipur () ( mni, Kangleipak) is a state in Northeast India, with the city of Imphal as its capital. It is bounded by the Indian states of Nagaland to the north, Mizoram to the south and Assam to the west. It also borders two regions of Myanm ...
, northeastern
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
. The
Khoibu community grinds the leaves with
ghost pepper
The ghost pepper, also known as ''bhut jolokia'' (which literally means 'Bhutan pepper' in Assamese), is an interspecific hybrid chili pepper cultivated in Northeast India. It is a hybrid of ''Capsicum chinense'' and '' Capsicum frutescens''.
...
s and a nut locally known as "bonra" to make a spicy side dish.
In
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
, the plant is being investigated as a source of
essential oil
An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...
(kesom oil).
[
]
Characteristics
The Vietnamese coriander is a perennial plant
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
that grows best in subtropical to tropical zones, in warm and damp conditions. In optimal conditions, it can grow up to .
The stem is jointed at each leaf. The top side of the leaves are dark green (with chestnut-coloured centre markings, typical of many ''Persicaria''), while the leaves’ undersides are a burgundy-red. This foliage colouring (green upper half, red or purple undersides) is indicative of a plant having evolved in lower or indirect light; I.e. the forest floor, where sunlight may be minimal or fleeting. Another example are the prayer plants, in the family ''Marantaceae
The Marantaceae are a family, the arrowroot family, of flowering plants consisting of 31 genera and around 530 species, defining it as one of the most species-rich families in its order.Kennedy, H. (2000). “Diversification in pollination mechan ...
'', especially ''Goeppertia
''Goeppertia'' is a genus of flowering plants in the family Marantaceae, native to the New World Tropics. It contains 243 accepted species, many of which were until recently assigned to '' Calathea''. It was first described by Nees von Esenbeck ...
'' or ''Stromanthe
''Stromanthe'' is a genus of flowering plants in the family Marantaceae, native to the tropical portions of the Americas from Mexico to Trinidad to northern Argentina.Idárraga-Piedrahita, A., R. D. C. Ortiz, R. Callejas Posada & M. Merello. (eds ...
''. In order to survive, the plants will use their leaves’ darker undersides to help reflect and maintain all absorbed sunlight on the leaf surfaces for optimal photosynthesis. If a plant has leaves that are entirely green, sunlight may pass through them more easily, but ultimately those species are likely to grow in more exposed locations.
In Asia, it can be found cultivated or growing in the wild. It can survive very well, as an outdoor perennial, in the Mediterranean regions of the world (coastal Western USA, Chile, South Africa, Western Australia and Southern Europe), as well as any equatorial nation, and anywhere where frosts or freezing conditions are not common. It prefers full sun and well-drained soil. For colder climate zones, they should be brought inside for the winter and treated as a house plant. For climate zones that have milder winters, they will survive outside, although their growth may slow down. It rarely flowers outside the tropics.
Components
Its oil contains aldehyde
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...
s such as decanal
Decanal is an organic compound classified as an aldehyde with the chemical formula C10H20O.
Occurrence
Decanal occurs naturally in citrus, along with octanal, citral, and sinensal, in buckwheat
Buckwheat (''Fagopyrum esculentum''), or com ...
(28%), and the alcohols dodecanol
Dodecanol , or lauryl alcohol, is an organic compound produced industrially from palm kernel oil or coconut oil. It is a fatty alcohol. Sulfate esters of lauryl alcohol, especially sodium lauryl sulfate, are very widely used as surfactants. Sod ...
(44%) and decanol
1-Decanol is a straight chain fatty alcohol with ten carbon atoms and the molecular formula C10H21OH. It is a colorless to light yellow viscous liquid that is insoluble in water and has an aromatic odor. The interfacial tension against water at ...
(11%). Sesquiterpene
Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modificat ...
s such as α-humulene and β-caryophyllene
Caryophyllene (), more formally (−)-β-caryophyllene, (BCP), is a natural bicyclic sesquiterpene that is a constituent of many essential oils, especially clove oil, the oil from the stems and flowers of ''Syzygium aromaticum'' (cloves), the esse ...
comprise about 15% of its oil.[Kesom Oil – a New Essential Oil for the International Flavour and Fragrance Industry ''in']
First Australian New Crops Conference 1996 – Volume 2
C-Methylated homoisoflavanone
Homoisoflavonoids (3-benzylidenechroman-4-ones) are a type of phenolic compounds occurring naturally in plants.
Chemically, they have the general structure of a 16-carbon skeleton, which consists of two phenyl rings (A and B) and heterocyclic rin ...
s ( 3-(4'-methoxy-benzyl)-5,7-dihydroxy-6-methyl-8-methoxy-chroman-4-one, 3-(4'-methoxy-benzyl)-5,7-dihydroxy-6,8-dimethyl-chroman-4-one, 3-(4'-hydroxy-benzyl)-5,7-dihydroxy-6,8-dimethyl-chroman-4-one, 3-(4'-hydroxy-benzyl)-5,7-dihydroxy-6-methyl-8-methoxy-chroman-4-one and 3-(4'-hydroxy-benzyl)-5,7-dihydroxy-6-methyl-chroman-4-one) can be found in the rhizomes of ''P. odoratum''.
Traditional uses
No scientific studies have measured ''P. odoratas effects on libido. Traditionally, in Vietnam, the herb is believed to repress sexual urges. A saying in Vietnamese states, ''"rau răm, giá sống"'' ("Vietnamese coriander, raw bean sprouts"), which refers to the common belief that Vietnamese coriander reduces sexual desire, while bean sprouts have the opposite effect. Many Buddhist
Buddhism ( , ), also known as Buddha Dharma and Dharmavinaya (), is an Indian religion or philosophical tradition based on teachings attributed to the Buddha. It originated in northern India as a -movement in the 5th century BCE, and ...
monks grow coriander in their private gardens and eat it frequently, believing it helps them remain celibate.Vietnamese Coriander (Persicaria odorata (Lour.) Soják) page
from Gernot Katzer's Spice Pages
Cultivation
North American sources state Persicaria odorata can be grown outside in frost free parts of
USDA Zones 9-11 in moderately fertile soil which is poor or well-drained but will remain moist to wet. It can tolerate full sun if there are breezes and boggy moist soil. However, part shade is desirable and it can be used as groundcover under trees.
If winter temperatures drop below 7°C/45°F overwintering indoors is possible if humidity can be maintained. Northern European sources proscribe all but summer under glass as it is
hardy to H1C (minimum 5-10°C) with West and South facing aspects preferable.
Persicaria odorata grows up to 6-18 inches tall and wide (15-45 cm) in US and UK sources state 1 metre height by 1.5 m spread are possible in 2 to 5 years.
Pests and diseases are not regarded as being problematic and it is even resistant to deer and rabbit.
Propagation
Propagate by seed in autumn or spring but flowering and seed harvests are rare in non tropical climes.
In summer, propagation via semi-ripe cuttings should be straightforward. Rooting cuttings in water is so easy that North American sources recommend against overwintering indoors where humidity cannot be maintained. Rather, source fresh bunches of rau răm in early spring cost effectively from Asian supermarkets. Remove the young leaves at the very top of the stems and any large leaves along the stems. Trim the bottom off stems to the first healthy
internode and place in water until 1-2 cm roots appear below the lowest node and then plant in soil. Expect to harvest around two months later.
References
External links
How to grow Persicaria odorataVietnamese instructional video on Persicaria odorata cultivation and propagationEnglish language instructional video on Persicaria odorata cultivation and propagation
{{Taxonbar, from=Q2593236
odorata
Malay cuisine
Flora of China
Flora of Indo-China
Plants described in 1790
Herbs
Medicinal plants