Ludwigia palustris
(marsh seedbox)

Preferred Common Name

• marsh seedbox

Other Scientific Names

• Cubospermum palustre (L.) Lour.
• Dantia palustris (L.) Des Moul.
• Isnardia palustris L.
• Quadricosta palustris (L.) Dulac
• Tiphogeton palustre (L.) Ehrh.

International Common Names

• English: Hampshire-purslane; marsh ludwigia; marsh-purslane; water-purslane
• Spanish: ludwigia rastrera; verdolaga de agua; verdolaga de pantano

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Myrtales
•                         Family: Onagraceae
•                             Genus: Ludwigia
•                                 Species: Ludwigia palustris

The family Onagraceae comprises 22 genera and about 656 species distributed worldwide. Ludwigia is a cosmopolitan genus with 83 species of herbs and shrubs currently placed in 23 sections and it is the only member of the subfamily Ludwigioideae (Wagner et al., 2007; Pesamosca and Boldrini, 2015; Liu et al., 2017; Stevens, 2020). The most recent study evaluating the molecular phylogeny of Ludwigia suggested that polyploidy is extremely common in this genus and species can be arranged in two groups: the North Temperate haplostemonous (NTH) group and a second group including all other species of Ludwigia (clade B) (Liu et al., 2017).

Perennial herbs with prostrate or ascending stems, rooting at the nodes, up to 50 cm or longer, well-branched and forming mats. Leaves 0.55-4.5 cm long, 0.25-2.3 cm, narrowly to broadly elliptic or ovate elliptic, glabrous, margin entire and minutely strigillose, hairs 0.05-0.1 mm long, apex subacute, base abruptly attenuated into narrowly winged petioles 1.2-25 mm long, bracteoles minute, 0.25-1(-1.8) mm long, 0.05-0.8 mm wide, ± linear, flanking ovary base or attached up to 2.5 mm above base, sometimes on very short pedicels. Flowers axillary and usually paired, sepals green, ovate deltate, 1.1-2 mm long, 1-2.1 mm wide, ascending, glabrous, apex acuminate, sometimes with a blunt tip, margin finely serrulate and minutely strigillose, the hairs 0.02-0.05 mm long, petals absent, anthers 0.2-0.4 mm long, 0.3-0.6 mm wide, staminal filaments translucent, 0.4-0.6 mm long, pollen shed singly, nectary disc green, elevated 0.15-0.3 mm on ovary apex, 1-2 mm across, 4-lobed, glabrous, style pale green, 0.35-0.7 mm long, glabrous, stigma whitish, subglobose, 0.2-0.4 mm across. Fruit a capsule irregularly dehiscent, (1.6-)2-5 mm long, 1.5-3(-3.5) mm in diameter, oblong obovoid or oblong with abruptly constricted base, minutely strigillose, the hairs ca. 0.05 mm long, with a green, longitudinal band 0.4-1 mm wide on the central part of each side of the capsule, representing the thinnest part of the fruit wall, obscurely 4-angled, dull light brown, subsessile or with pedicels up to 0.5 mm long. Seeds numerous, pluriseriate and free, 0.5-0.7 mm long, 0.3-0.35 mm wide, ellipsoid, yellowish-brown, the surface cells transversely elongate, with inconspicuous raphe (Wagner et al., 2005).

Soil drainage

• seasonally waterlogged

Soil reaction

• alkaline
• neutral

Soil texture

• heavy
• light
• medium

Ludwigia palustris spreads by seeds and vegetatively by rooting at nodes and by stem fragments dispersed in water flow (NZPCN, 2020). It readily grows from fragments and it is common to find small populations in the vicinity of large permanent populations (Online Atlas of the British & Irish Flora, 2020). The tiny seeds of this species can also adhere to the feathers or muddy feet of ducks and geese and in this way, seeds are probably spread to new wetlands (Hilty, 2019).

Ludwigia palustris is listed as invasive in Australia and Guadeloupe, but it is also regarded as an environmental weed in Bermuda, Hawaii and New Zealand (Wagner et al., 2005; UICN-CF, 2016; Queensland Government, 2018; NZPCN, 2020; Online Atlas of the British & Irish Flora, 2020; POWO, 2020; USDA-NRCS, 2020). In Australia, L. palustris has escaped cultivation as an aquatic ornamental and become a highly invasive weed of permanent freshwater wetlands, waterways and riparian areas where it often displaces and outcompetes native vegetation (Queensland Government, 2018).

L. palustris is also listed as a problematic species in areas within its native distribution range (e.g. USA, South Africa and Mexico) because it can overgrow and obstruct water flow. It also competes with other native aquatic vegetation and easily becomes the dominant species in native habitats (CONABIO, 2006; Hoch and Grewell, 2012; USDA-NRCS, 2020).

• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Long lived
• Fast growing
• Has high reproductive potential
• Gregarious
• Reproduces asexually

• Monoculture formation
• Reduced amenity values
• Reduced native biodiversity
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - smothering
• Rapid growth
• Rooting

• Highly likely to be transported internationally accidentally
• Highly likely to be transported internationally deliberately
• Difficult to identify/detect as a commodity contaminant
• Difficult to identify/detect in the field

Ludwigia palustris is used as ornamental for aquariums and ponds (NZPCN, 2020; USDA-ARS, 2020).