Riceweeds en - Onagraceae - Ludwigia adscendens (L.) H.Hara

LUDAD

Onagraceae

Ludwigia adscendens (L.) H.Hara

Broadleaf

A creeping/floating aquatic perennial herb, stem often purple-red, prostrate or ascending carrying pink spongy roots at the nodes. Leaves 1.25-7.6 cm long, obovate or oblanceolate, obtuse. Flowers white, slightly yellow at the base, axillary, solitary; petals about 1.25 cm long, obovate. Capsule linear-cylindric, 1.27(-2)-3.8 cm long.

Rooting at nodes, with white, erect, short (1-3 cm), spindle-shaped pneumatophores in clusters at nodes of floating stems.

Stem often purple-red, prostrate or ascending carrying pink spongy roots at the nodes.

Leaves 1.25-7.6 (-10) cm long, 4 cm wide obovate or oblanceolate, obtuse. Leaves alternate, broadly, rounded or obtuse at apex, narrowed at the base to a distinct petiole which may be red.

The inflorescence is solitary.

Flowers solitary in the upper leaf axils, pale yellow with a darker spot at the base of the petals. Sepals (4-5) of 5.5-12 mm of length; stamens (8-)10. Pollen grains shed individually. Disk slightly elevated, with a depressed white-hairy nectary surrounding the base of each epipetalous stamen.

Capsule linear-cylindric, 1.27(-2)-3.8 cm long.

Pale brown, many in orderly rows, some 4-angled and some prismoid, 1 to 2 mm in size.

Propagation is mainly by seed, but extensive creeping stems, on mud or water, may help a single plant to colonize a significant area.

In rather dry to very dry climates, in pools, ditches. from 0-1600 m alt. Lowland-irrigated, rainfed, and rice fields. The plant thrives in a variety of soils in the rice paddies of the world.

S.E. Asia and Malesia.

A weed of minor importance; it can obstruct the free surface of waters.

Benin: Frequent but not abundant.
Burkina Faso: Frequent but not abundant.
Chad: Rare and not abundant.
Côte d'Ivoire: Frequent but not abundant.
Ghana: Frequent and usually abundant.
Mali: Rare but abondant when present
Nigeria: Frequent but not abundant.
Senegal: Frequent but not abundant.

Taller plants mechanically weeded. The plants are often attacked by leaf-eating insects which destroy the plant. Tilapia (fish) feeds on its roots and stems.
At an early growth stage the plants are easily killed by 2.4-D or MCPA or a foliar spraying with 2.4-D ester or amine (480 g/l).
Management options: http://www.afroweeds.org/network/pg/file/read/1902/general-guidelines-for-weed-management-in-lowland-rice

D.E. Johnson (1997). Les adventices en riziculture en Afrique de l'Ouest /Weeds of rice in West Africa. West Africa Rice Development Association, Bouaké, Côte d'ivoire. 242p.
Grard, P., Homsombath, K., Kessler, P., Khuon, E., Le Bourgeois, T., Prospéri, J., Risdale, C. 2006. Oswald V.1.0: A multimedia identification system of the major weeds of rice paddy fields of Cambodia and Lao P.D.R. In Cirad [ed.]. Cirad, Montpellier, France. Cdrom. ISBN 978-2-87614-653-2.
Holm, Leroy G., Plucknett, D. L., Pancho, J. V., Herberger, J. P. 1977. The world's worst weeds: distribution and biology. East-West Center/University Press of Hawaii. 442p.
Troupin G. (1989). Flore du Rwanda, Spermatophyte (Volume II). Musée Royal de l'Afrique centrale, Tervuren, Belgique. 303p
Soerjani M., Kostermans A. J. G. H., Tjitrosoepomo G. 1987. Weeds of rice in Indonesia. Balai Pustaka. Jakarta.

Medicinal plant of Bangladesh: http://www.mpbd.info/plants/ludwigia-adscendens.php
KEW: http://apps.kew.org/efloras/namedetail.do?flora=fz&taxon=3709&nameid=8859