Common name : Niruri
Common name in Hindi : Hazardana
Bangla English Hindi Urdu
Diagnostic characters
Biology
Ecology and distribution
Nuisance
Weed control
Botany
Uses/Remark
References
P. niruri is an erect, slender, branched, annual herb from 10 to 50cm, of a light green to whitish. The leaves of the main stem fall very early, so that the side, horizontal and rather brief twigs, look like compound leaf.
It has numerous small leaves which are simple, elliptic to elongated, carrying minute flowers to their base.
Flowers are of small size and greenish. On half lower of the twigs, flowers are solitary, while they are grouped by 2 - 4 on terminal half.Seeds, wedge-shaped are of a light brown.
P. niruri is an annual species. It multiplies by seeds. The seeds could be dispersed by the water and by animals.
Now pantropical in distribution, it is believed to have originated in tropics of Asia, where is particularly troublesome. It occurs in gardens and roadsides and thrives in full sunlight from sea level to 1800 m. It can not survive in dry or dry zone everywhere.
P. niruri is a pioneer species and is one of the first to appear at the start of the rainy season. It grows in wet soils and mature plants tolerate complete flooding for several years without injury. Plants can grow as epiphytes in the leaf axils of oil palm.
In India, P. niruri is most frequently reported in rice, maize, cassava, sorghum and in dry land crops. It is also a serious weed of beans.
In Bangladesh and India it is reported as a common weed of sugarcane and jute.
In Nepal it is reported as a weed of rice fields and sugarcane.
- Chemical
1.1kg MSMA plus 0.45 kg 2_4-D + 2.3 kg sodium chlorate in 41 liter of water, at 4-week intervals.
Post-emergence: paraquat or paraquat with monuron or diuron; propanil in rice. Sequential amitrole- paraquat treatment is effective.
Post-emergence application of 2_4-D at 500 g.i/ha or Almix at 4 g/ha.
Habit
Erect, slender, hairless plant 10 to 50cm tall. The main axis is quickly branched. The secondary twigs look like compound leaves.
Roots
Taproot slender, wiry, provided with fine secondary roots.
Stem
Cylindrical and hairless, on that persists, at the level of the leaves insertion, triangular stipules, acuminates and often cordated in the base. It exudes translucent latex when it is cut.
Leaves
Simple, alternate, hairless and subsessiles, pale green above, with pinnated venation little visible. At the base of the petiole 2 stipulate threadlike reduced, of unequal length and fast blacks. The lamina is elliptic to elongated, long from 8 to 12mm and wide from 3 to 5,5mm, with round or blunt summit, sometimes briefly apiculated, the base rounded and in entire margin. Two faces are hairless.
Inflorescence
Solitary minute flowers unisexual. Female flowers axillaries in the base of twigs, the male flowers regrouped by 2 - 4 in the axils of leaves in the top of twigs. Female flowers in peduncle 2mm long, with 5 sepals. The disc is flattened, small, with 5 lobes. The ovary is spherical surmounted of a short trifid style. Male flowers in hail peduncle, 0,5mm long, with 5 elliptic sepals and 3 welded stamens.
Fruit
Capsule dehiscent in 3 cell with 2 seeds each. The capsule is globose, depressed, and smooth, 2mm in diameter, that appears to the face lower of twigs.
Seeds
Wedge-shaped, one concave and two flat sides, beige, 1mm in height. Seeds on the back longitudinally ribbed, on the sides concentrically ribbed, in between and over the ribs finely transversely ribbed.
Seedling
Cotyledons very reduced, they measure 5mm in length and 2mm of wide, elliptic and sessile, placed at 2cm over the ground.
First leaves subsessile and elliptic, hardly bigger than cotyledons. The following ones elliptic to elongated, with a round summit.
P. niruri has been confused with similar species. In India, Mitra and Jain (1985) consider P. niruri to be a mixture of three species (P. amarus, P. fraternus and P. debilis). After describing the characteristics of each, they combine these species into P. niruri complex.
- Le Bourgeois T., Jeuffrault E., Grard P., Carrara A. 2001. AdvenRun V.1.0. Les principales mauvaises herbes de La Réunion. CD-ROM. Cirad, SPV. France.
- Holm L., Doll J., Holm E., Pancho J., Herberger J. 1997. World weeds. Natural Histories and Distribution. John Wiley & Sons. New York.
- Soerjani M., Kostermans A. J. G. H., Tjitrosoepomo G. 1987. Weeds of rice in Indonesia. Balai Pustaka. Jakarta.
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