The Vietnamese coriander is a perennial plant that grows best in tropical and subtropical zones in warm and damp conditions. In advantageous conditions, it can grow up to 15 to 30 cm. In the winter or when the temperature is too high, it can wither.
The top of its leaf is dark green, with chestnut-colored spots while the leaf's bottom is burgundy red. The stem is jointed at each leaf. In Vietnam it can be cultivated or found in the wild. It can grow very well outside in summer in non-tropical europe...preferring full sun and well-drained soil and is ideal here for pots and tubs. It should be brought inside for winter and treated as a house plant. It rarely flowers outside the tropics, but it is the leaves that have strong culinary use.
Vietnamese coriander is one of those numerous herbs that give Vietnamese cuisine its unique touch. The herb is, though, also used outside of Vietnam: It appears in Malaysian recipes and is quite typical of the Singaporean cuisine.
In Vietnam, particularly in the South, fresh herbs are a conditio sine qua non of food. A typical South Vietnamese noodle soup (pho [phở]) is based on broth (often from chicken, pork or fish, or a combination therefrom) with a variety of different ingredients, which usually include small meat pieces, boiled and raw vegetables, fish balls, young onion greens and fried garlic slices. The soup is served with a large amount of additional flavorings, which are left to the diner to finalize his soup: lime wedges, mustard paste, nuoc mam [nước mắm] fish sauce, fresh red chile slices and a host of herbs which are dipped into the soup using chopsticks and eaten together with a spoonful of soup. Similarly, stir-fried meat and vegetables are never seen without generous amounts of chopped herbs, and the same holds for the tasty Vietnamese sandwiches, a colonial heritage. Since Vietnamese cooking is far less spicy than, for example, Thai cooking, the herbs are indispensable for the true taste of Vietnam.
Traditionally, in Vietnam Persicaria odorata is believed to repress sexual urges. There is a saying in Vietnamese, "rau răm, giá sống" ("Vietnamese coriander, raw bean sprouts") meaning that Vietnamese coriander has the ability to reduce sexual desires, while bean sprouts have the opposite effect. Many Buddhist monks grow coriander in their private gardens and eat it frequently as a helpful step in their celibate life.
J Agric Food Chem. 2006 Apr 19;54(8):3067-71. Comparison of volatile constituents of Persicaria odorata(Lour.) Soják (Polygonum odoratum Lour.) and Persicaria hydropiper L. Spach (Polygonum hydropiper L.). Starkenmann C, Luca L, Niclass Y, Praz E, Roguet D.
Corporate R&D Division, Firmenich SA, P.O. Box 239, CH-1211 Geneva 8, Switzerland. christian.starkenmann@firmenich.com
Polygonum odoratum Lour. has been reclassified as Persicaria odorata (Lour.) Soják [Wilson, K. L. Polygonum sensu lato (Polygonaceae) in Australia. Telopea 1988, 3, 177-182]; other synonyms currently used are Vietnamese mint or Vietnamese coriander and, in Malaysia, Daun Laksa or Laksa plant. The aerial parts of Laksa plant are highly aromatic, and they contain many organic compounds such as (Z)-3-hexenal, (Z)-3-hexenol, decanal, undecanal, and dodecanal that are typical for green, citrus, orange peel, and coriander odors. In addition to these aldehydes, 3-sulfanyl-hexanal and 3-sulfanyl-hexan-1-ol were discovered for the first time in this herb. The fresh leaves are pungent when they are chewed, although the active compound has never been identified. The pungency of Persicaria hydropiper (L.) Spach (formerly Polygonum hydropiper L., synonym water pepper) is produced by polygodial, a 1,4-dialdehyde derived from drimane terpenoids. We also identified polygodial as the active pungent compound in P. odorata (Lour.) Soják.
Agricultural Sci. J. 42(2)(Suppl.): 105-108 (2011) .. ...... ... 42(2)( .!".): 105-108 (2554)
.....Antibacterial Activity of the Essential Oil from Persicaria odorata Leaves
This study conducted to identify physicochemical properties and antibacterial activity of the essential oils from Vietnamese Coriander (Persicaria odorata). Hydrodistillation was used to extract the essential oil from the fresh and dry leaves of Persicaria odorata. Using a Gas Chromatography-Mass Spectrometry (GC-MS analysis), dodecanal, caryophyllene, alpha-caryophyllene, drimenol and decanal were identified as a major volatile compounds. The antibacterial testing was conducted by disc diffusion method. The essential oils from both of fresh and dry leaves of Persicaria odorata exhibited antibacterial activity against both of gram positive bacteria such as Staphylococcus aureus and gram negative bacteria such as Escherichia coli. Moreover, the highest antibacterial activity was shown by essential oil from dry leaves which against S. aureus exhibited an inhibition zone at 26 mm for 100μl/ml concentration.
http://kruidwis.blogspot.fr/2014/02/vietnamese-koriander-in-mijn-wintertuin.html
to microbial infections, inflammation, pain, allergy, uterine disorders, fertility, obesity, and improvement of memory.