Ludwigia palustris is a species of flowering plant in the evening primrose family known by the common names marsh seedbox, Hampshire-purslane and water purslane. This is an aquatic or semiaquatic perennial herb which grows in moist to wet to flooded areas. It is sometimes a weed. The species epithet palustris is Latin for "of the marsh" and indicates its common habitat.

Description L. palustris forms prostrate, sprawling mats in wet, disturbed areas. Its stems are semi-succulent, reddish in color, and smooth or slightly hairy. As the stems spread along the ground, roots form from the nodes. At maturity, the stems may reach 10-40 cm long.Cooke, S.S, ed. 1997. A Field Guide to the Common Wetland Plants of Western Washington and Northwestern Oregon. Seattle Audubon Society and Washington Native Plant Society. Seattle Ausubon Society, Seattle, WA, 417pp. Hitchcock, Leo C. and Arthur Cronquist. 1973. Flora of the Pacific Northwest. University of Washington Press, Seattle, WA, and London, England, 730pp.

The leaves are opposite, smooth, oval-shaped, and reach up to 4 cm long. They have a winged petiole and are often reddish-green in color.

The greenish-white flowers are born on the leaf axils and reach 2-3 cm long. They lack petals, and are composed of 4 triangular-shaped sepals and 4 white-tipped stamens, set above a cube-shaped, 4-angled ovary.

The fruits are small, cube-shaped capsules, 2-3 cm long. They are pale green in color, with darker green stripes along the angles. The sepals are persistent, remaining present on the developed fruits.

Taxonomy Ludwigia palustris was given the scientific name Isnardia palustris in 1753 by Carl Linnaeus. It was moved to the genus Ludwigia by Stephen Elliott in 1817. Together with its genus it is classified in the family Onagraceae. Though it has not accepted varieties, there are five variety names among its 21 synonyms.

Table of Synonyms Name Year Rank Notes Dantia palustris 1859 species ≡ hom. Isnardia ascendens 1840 species = het. Isnardia nitida 1813 species = het. Isnardia palustris 1753 species ≡ hom. Isnardia palustris var. americana 1828 variety = het. Isnardia palustris var. riparia 1824 variety = het. Isnardia palustris var. rivularis 1824 variety = het. Isnardia palustris f. submersa 1911 form = het. Jussiaea isnardia 1901 species = het. Ludwigia apetala 1788 species = het. Ludwigia nitida 1803 species = het. Ludwigia palustris var. americana 1935 variety = het. Ludwigia palustris f. elongata 1939 form = het. Ludwigia palustris var. inundata 1935 variety = het. Ludwigia palustris var. liebmannii 1912 variety = het. Ludwigia palustris var. nana 1935 variety = het. Ludwigia palustris var. pacifica 1935 variety = het. Ludwigia palustris f. submersa 1933 form = het. Ludwigia palustris var. typica 1935 variety ≡ hom., not validly publ. Peplis portula 1818 species = het., nom. nud. Quadricosta palustris 1867 species ≡ hom. Notes: ≡ homotypic synonym; = heterotypic synonym

Distribution and habitat L. palustris is circumpolar species with a large native range. It occurs in North America, South America, Africa, Asia, and Europe. It occurs as a naturalized or invasive species in Hawaii, Australia, and New Zealand.

The species is generally restricted to low elevations, where it grows on shallow bodies of water such as reservoirs, ditches, and the banks of ponds, rivers, and streams. It requires wet, muddy or sandy soils poor in calcium but rich in humus and nutrients.

Conservation status L. palustris is designated by the IUCN Red List and NatureServe as a secure (G5) species globally. In North America, it is also designated as secure (N5) in both Canada and the United States. In some states and provinces, it is designated to be at higher risk. In both Arizona and Prince Edward Island, it is ranked as a critically imperiled (S1) species. In New Mexico it is imperiled (S2). In Kansas, Iowa, and Quebec it is vulnerable (S3).

The plant can be highly invasive outside its native range, very adaptable, and reproduces asexually. Ludwigia palustris poses a potential threat to wetland vegetation in Victoria, Australia. It has spread to riverbanks in Northeastern Australia and other areas.

Cultivation L. palustris is cultivated for use in aquariums and aquascaping. It is often sold under the names Ludwigia 'super red', Ludwigia 'mini super red', or Ludwigia 'red'.

References

External links Jepson Manual Treatment Missouri Plants Photo Profile Illinois Wildflowers VT Weed Identification Photo gallery