The creeping water-primrose (Ludwigia peploides) is a perennial aquatic plant whose long stems creep over mud or shallow water, sometimes forming dense mats which float on the water’s surface (2) (3) (4) (5) (6). This species is named for its yellow, primrose-like flowers, while its long, oval leaves resemble those of willows, leading to its alternative name of ‘floating primrose-willow’ (7).
Although often long and narrow, the leaves of the creeping water-primrose vary in shape and can also be rounded or egg-shaped, particularly on young shoots (3) (4) (5) (6) (8). The leaves have smooth edges, grow at alternating points along the stems (5) (6) (8) and can measure up to ten centimetres in length (2).
The stems of the creeping water-primrose are fleshy and can have either a smooth or slightly hairy surface (3) (4) (5) (8). This species has two types of roots, the first anchoring the plant to the soil and taking in nutrients while the second aids in the uptake of oxygen (3) (4). The second type of root occurs at intervals along the plant’s stems (3) (4) and allows the creeping water-primrose to re-grow from stem fragments (4).
Each of the creeping water-primrose’s bright yellow flowers has five petals (2) (3) (4) (5) (6) (8) and grows on a long stalk arising from a leaf axil, where the leaf attaches to the plant stem (3) (4) (5) (6). The flowers of this species are reported to be around one to three centimetres in diameter (3) (5) (8). The fruit of the creeping water-primrose is a long, narrow, cylindrical capsule around one to four centimetres in length (2) (4) (6) which contains numerous small seeds (3) (4) (5) (8).
Three subspecies of creeping water-primrose are currently recognised: Ludwigia peploides peploides, Ludwigia peploides montevidensis and Ludwigia peploides glabrescens (1) (2). The creeping water-primrose is very similar in appearance to a number of closely related species, and can sometimes be difficult to tell apart (3) (4) (5) (8). Compared to Ludwigia grandiflora and Ludwigia hexapetala, the creeping water-primrose has more horizontal stems and slightly smaller flowers (3).
- Also known as
- creeping water primrose, creeping waterprimrose, creeping water-purslane, floating evening primrose, floating primrose, floating primrose willow, floating primrosewillow, floating primrose-willow, floating water primrose, floating water-primrose, water primrose.
- Jussiaea gomezii, Jussiaea patibilcensis, Jussiaea peploides, Jussiaea polygonoides, Jussiaea repens var. peploides, Ludwigia adscendens var. peploides, Ludwigia clavellina var. peploides.
- Stem length: up to 3 m (2)
Creeping water-primrose biology
In its non-native range in Europe, the creeping water-primrose usually flowers between July and October (3) (4) (8). The flowers of this species are pollinated by insects (4).
Although it produces seeds, the creeping water-primrose spreads mainly by vegetative reproduction, with broken-off fragments of its stems easily rooting and growing into new plants (3) (4) (5) (7) (8). Its stems are buoyant, and stem fragments may float away from the parent plant or be carried away by animals or humans (3) (4).
The creeping water-primrose grows very rapidly in the spring but dies back in autumn (3) (8). Submerged or buried parts of the plant can survive the winter months and re-grow the following year (4).
Creeping water-primrose range
The creeping water-primrose is native to South America, Central America and the southern United States (3) (4) (5).
This species is considered to be invasive, and has been introduced and become established in a number of locations outside of its natural distribution, including France, Belgium, Italy, the Netherlands, Spain, Portugal, Switzerland and the United Kingdom (3) (4) (7) (8), as well as Australia, New Zealand, and parts of the United States beyond its native range (2) (3) (4).
Creeping water-primrose habitat
The creeping water-primrose typically inhabits still or slow-flowing freshwater habitats (7) (8), including the margins of ponds, slow-flowing rivers, marshes, ditches, streams and rice fields (3) (5) (6). This adaptable species is capable of growing under a variety of different conditions in terms of nutrient levels, water quality and substrates (4). As its roots are able to absorb atmospheric oxygen, the creeping water-primrose is able to survive in poorly oxygenated waters (4), and it is also reported to be relatively tolerant of frosts (3).
As well as being able to grow in water up to 3 metres deep, with its stems potentially extending up to 80 centimetres above the water’s surface (3) (4), the creeping water-primrose is also able to colonise damp terrestrial habitats such as wet meadows (4).
Creeping water-primrose status
The creeping water-primrose has yet to be classified by the IUCN.
Creeping water-primrose threats
The creeping water-primrose is a widespread species and is not currently considered to be facing any major threats. Outside of its natural range, this species has been introduced as an ornamental plant in ponds and gardens, but has escaped into the wild and become invasive (3) (7) (8). In France, the creeping water-primrose is considered to be one of the country’s most widespread and damaging invasive plant species (3).
The dense floating mats of vegetation that the creeping water-primrose forms can out-compete native plant species and clog waterways, increasing the risk of flooding and affecting recreation, fishing and navigation (3) (4) (8). This species also alters the chemistry of the aquatic environment, reducing dissolved oxygen levels by shading out submerged plants and reducing the transfer of oxygen between the water and air. It can also alter sulphide, phosphate and nitrate levels and water pH. These changes can make the habitat unsuitable for native species (3) (4) (5).
By altering the aquatic habitat, the creeping water-primrose can also make it unsuitable or impassable for invertebrates and fish. In addition, this plant can out-compete native wetland grasses, taking over pastures and reducing the area that can be grazed by livestock. By blocking water channels and slowing water flow, the creeping water-primrose can increase sedimentation in the water, and it can also create a breeding habitat for mosquitoes (3) (4).
No specific conservation measures are currently needed for this highly invasive plant, and efforts are underway to control or eradicate it from its non-native range. Where the creeping water-primrose causes a problem, it may be removed manually or with machinery, although care needs to be taken to remove all fragments and roots so that it does not re-grow (3) (4) (5) (9). Herbicides or plant-eating insects could also potentially be used to control creeping water-primrose populations (3) (4).
As the creeping water-primrose has mainly been spread through the ornamental plant trade, efforts to educate retailers and the public about the problems it can cause would be beneficial (3) (10). In France, the sale of this species and its introduction into the wild has been prohibited since 2007 (4), and its sale is also to be banned in the United Kingdom (9) (10), where it is an offence to plant the creeping water-primrose in the wild or to allow it to grow there (8) (9). A number of other countries have also banned the sale of this species (4), and it is listed as a noxious weed in Washington, U.S., which means that sale or transport of the species is prohibited and its eradication is required by law (5) (11).
Despite the creeping water-primrose’s invasiveness, some studies have investigated the potential use of this plant in treating wastewater, as it is capable of removing nitrates from the water (3) (11).
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- Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.
- A plant that normally lives for more than two seasons. After an initial period, the plant produces flowers once a year.
- To transfer pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.
- A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
- Vegetative reproduction
- Type of asexual reproduction (reproduction that does not involve the formation of sex cells) in which a new plant grows from part of another plant, rather than from seeds or spores. The resulting individual is genetically identical to the original plant.
Integrated Taxonomic Information System (ITIS) (September, 2013)
Smithsonian National Museum of Natural History: Onagraceae - The evening primrose family (September, 2013)
Invasive Species Compendium: Datasheets - Ludwigia peploides (water primrose) (September, 2013)
European and Mediterranean Plant Protection Organization (2011) Data sheets on quarantine pests: Ludwigia grandiflora and L. peploides Onagraceae - Water primroses. EPPO Bulletin, 41: 414-418.
Washington State Noxious Weed Control Board - Floating primrose-willow (September, 2013)
Bryson, C.T. and DeFelice, M.S. (2009) Weeds of the South. University of Georgia Press, Athens, Georgia.
GB Non-native Species Secretariat (NNSS): Factsheet - Floating water-primrose (September, 2013)
GB Non-native Species Secretariat (NNSS): Identification Sheet - Creeping water-primrose (September, 2013)
Plantlife - Floating water primrose (September, 2013)
Department for Environment, Food and Rural Affairs (2013) Sale of invasive water plants banned to protect wildlife. Press release, 29 January. Available at:
Washington State Department of Ecology: Non-native Invasive Freshwater Plants - Water primrose species (Ludwigia hexapetala - water primrose and Ludwigia peploides - floating primrose willow) (September, 2013)
Rejmánková, E. (1992) Ecology of creeping macrophytes with species reference to Ludwigia peploides (H. B. K.) Raven. Aquatic Botany, 43: 283-299.