Ludwigia hyssopifolia (G. Don) Exell
Seedbox, linear leaf water primrose
Jussiaea hyssopifolia G. Don (basionym); J. linifolia Vahl; Ludwigia micrantha (Kunze) Hara
South and Southeast Asia: Bangladesh, Cambodia, India, Indonesia, Lao PDR, Malaysia, Philippines, Sri Lanka, Thailand, and Vietnam.
Rest of the world: Colombia, Congo-Kinshasa, Benin, Egypt, Ghana, Honduras, Iraq, New Guinea, Nigeria, Senegal, Sudan, Suriname, and West Polynesia.
An erect annual herb, 15−150 cm tall and minutely hairy during early stage of growth.
Stem: often 3-4 angled, green or purplish, and with white spongy pneumatophores arising from submerged roots.
Leaf: lance-shaped, petioled, and up to 9 cm long.
Inflorescence: solitary flowers, borne at axils of leaves; 4 yellow petals, elliptic, up to 3 mm long.
Fruit: finely hairy, almost cylindrical, 1.75−2.5 cm long capsule.
Biology and ecology
Widespread, growing in wet places, shallow pools and ditches, margins of canals and in lowland rice fields.
Can produce approximately 250,000 seeds per plant; seeds released gradually and they remain floating in water up to 16 days before they sink. Seeds do not germinate under submerged conditions or when buried in soil. Seeds germinate in temperatures of 10−40ºC.
Can be a serious rice weed on both clay-loam and clay soils; in lowland rice fields.
Cultural: hand weeding and tillage are common means of controlling this weed in rice.
Chemical control: MCPA and 2,4-D as postemergence treatments and also quinclorac + bensulfuron or molinate + 2,4-D.
- Holm L, Pancho JV, Herberger JP, Plucknett DL. 1979. A geographical atlas of world weeds. New York (USA): John Wiley & Sons, Inc. 391 p.
- Moody K, 1989. Weeds reported in rice in South and Southeast Asia. Los Baños (Philippines): International Rice Research Institute. 442 p.
- Pancho JV, Kim JS. 1985. Reproductive biology of weeds in vegetables in the highlands of Benguet, Luzon, Philippines. Philipp. J. Weed Sci. 12:75-98.
- Pons TL. 1985. Factors affecting weed seed germination and seedling growth in lowland rice in Indonesia. Biotrop Bull. Trop. Biol. 23:47-57.
- Raju RA, Reddy MN. 1986. Protecting the world's rice crops. Agric. Inf. Dev. Bull. 8(2):17-18.
- Raven PH. 1977. Onagraceae. Flora Malesiana Ser. 1 8(2): 98-113.
- Singh D, Gangwar B. 1987. Ricefield weeds in South Andaman, India. International Rice Research Newsletter 12(4):47.
- Ludwigia hyssopifolia (G. Don) Exell. Global Compendium of Weeds home page at http://www.hear.org/gwc/html/index.html.