Ludwigia grandiflora
(water primrose)

Pictures

Picture	Title	Caption	Copyright
Title Flower Caption Ludwigia grandiflora (water primrose); flower. Copyright ©Trevor Renals/via http://www.nonnativespecies.org - CC BY 2.0 UK	Flower	Ludwigia grandiflora (water primrose); flower.	©Trevor Renals/via http://www.nonnativespecies.org - CC BY 2.0 UK
Title Flowering habit Caption Ludwigia grandiflora (water primrose); flowering habit. Grand étang de Saint Estèphe, commune de Saint-Estèpe, Dordogne, France. September, 2012. Copyright ©Traumrune-2012/via wikipedia - CC BY-SA 3.0	Flowering habit	Ludwigia grandiflora (water primrose); flowering habit. Grand étang de Saint Estèphe, commune de Saint-Estèpe, Dordogne, France. September, 2012.	©Traumrune-2012/via wikipedia - CC BY-SA 3.0
Title Flowering habit Caption Ludwigia grandiflora (water primrose); flowering habit. Copyright ©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK	Flowering habit	Ludwigia grandiflora (water primrose); flowering habit.	©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK
Title Flowering habit Caption Ludwigia grandiflora (water primrose); flowering habit. (subsp. hexapetala). Saint-Mathurin-sur-Loire, Maine-et-Loire, France. August, 2007. Copyright ©Olivier Pichard-2007/via wikipedia - CC BY-SA 3.0	Flowering habit	Ludwigia grandiflora (water primrose); flowering habit. (subsp. hexapetala). Saint-Mathurin-sur-Loire, Maine-et-Loire, France. August, 2007.	©Olivier Pichard-2007/via wikipedia - CC BY-SA 3.0
Title Habit Caption Ludwigia grandiflora (water primrose); habit. Copyright ©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK	Habit	Ludwigia grandiflora (water primrose); habit.	©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK
Title Habit Caption Ludwigia grandiflora (water primrose); habit. Copyright ©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK	Habit	Ludwigia grandiflora (water primrose); habit.	©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK
Title Habit Caption Ludwigia grandiflora (water primrose); habit. Copyright ©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK	Habit	Ludwigia grandiflora (water primrose); habit.	©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK
Title Habit Caption Ludwigia grandiflora (water primrose); habit. Copyright ©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK	Habit	Ludwigia grandiflora (water primrose); habit.	©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK
Title Habit Caption Ludwigia grandiflora (water primrose); habit. Copyright ©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK	Habit	Ludwigia grandiflora (water primrose); habit.	©Crown Copyright/GBNNS/via via http://www.nonnativespecies.org - CC BY 2.0 UK

Identity

Preferred Scientific Name

• Ludwigia grandiflora (Michx.) Greuter & Burdet, 1987

Preferred Common Name

• water primrose

Other Scientific Names

• Jussiaea grandiflora Michx., non Ruiz & Pavón
• Jussiaea michauxiana Fern. (excl. type)
• Jussiaea repens var. grandiflora M. Micheli
• Jussiaea uruguayensis Camb.
• Ludwigia grandiflora (M. Micheli) Greuter & Burdet
• Ludwigia hexapetala (Hook. & Arn.) Zardini, Gu & Raven
• Ludwigia uruguayensis var. major (Hassler) Munz

International Common Names

• English: large flower primrose willow; large-flower primrose-willow; primrose willow; Uruguay waterprimrose; Uruguayan Hampshire-purslane; Uruguayan primrosewillow; Uruguayan primrose-willow
• Spanish: duraznillo de agua
• French: jussie à grandes fleurs; ludwigie à grandes fleurs

Local Common Names

• Germany: Flutende Heusenkraut; Grossblütiges Heusenkraut

Summary of Invasiveness

L. grandiflora is a productive emergent perennial native to South and Central America and parts of the USA. It was introduced to France in 1830 and has become one of the most damaging invasive plants in that country (Dandelot et al., 2008). It was more recently introduced beyond its native range in the USA, where it also causes severe problems (IPAMS, 2009). In its adventive range, L. grandiflora can transform ecosystems both physically and chemically. It can sometimes be found growing in impenetrable mats; under these conditions, L. grandiflora can displace native flora and interfere with flood control and drainage systems, clog waterways and impact navigation and recreation (IPAMS, 2009). The plant also has allelopathic activity that can lead to dissolved oxygen crashes and the accumulation of sulphide and phosphate in the water. These not insubstantial and year-round effects on water quality can cause ‘dystrophic crises’ and intoxicated ecosystems (Dandelot et al., 2005).

Taxonomic Tree

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

Notes on Taxonomy and Nomenclature

Ludwigia, the only genus in the Jussiaeeae tribe, is both very large and very diverse, with around 82 species in 23 sections (Zardini et al., 1991b). L. grandiflora was originally listed along with closely-related Ludwigia hexapetala as separate species Ludwigia uruguayensis, which was at the time understood to be one of the most variable members of sect. Oligospermum. Evidence from Zardini et al. (1991a), however, revealed that in fact, L. uruguayensis included two chromosomal variants: a hexaploid (n = 24) and a decaploid (n = 40) form. This observation formed the basis of splitting L. uruguayensis to L. hexapetala and L.grandiflora. However, Nesom and Kartesz (2000) argue for treating the two species as subspecies (L. grandiflora subsp. grandiflora and L. grandiflora subsp. hexapetala, comb. et stat. nov.), and both treatments can be found in recent literature (cf Okada et al., 2009; Ruaux et al., 2009).

Description

L. grandiflora is an emergent, aquatic, herbaceous perennial with two growth forms. During the first growth stage, the plant produces smooth or sparsely pubescent stems that grow horizontally over the soil or water, rooting at nodes and producing white, spongy roots. Leaves are smooth, alternate and have petioles. During the second stage, shoots begin to grow vertically and flower, stems become pubescent and can grow up to 1 m tall (USACE-ERDC, 2009). Leaves tend to be more elongate in the second growth form (IPAMS, 2009), but can vary widely in shape from lanceolate to elliptic and acute at both ends (USACE-ERDC, 2009). Flowers are on solitary stalks that are approximately 2.5 cm long; actinomorphic; sepals 5 (rarely 6), villous or glabrous; petals 5, caducous, obovate, emarginate, bright golden-yellow with a darker spot at the base; stamens in 2 whorls, the epipetalous ones shorter; disc slightly elevated, with a depressed, white-hairy nectary surrounding the base of each epipetalous stamen; style glabrous or hairy in lower two-third. Fruit is a pubescent light-brown capsule, 2.5 cm long containing 40-50 seeds, 1.5 mm long, embedded in a woody endocarp (IPAMS, 2009).

Plant Type

Distribution

L. grandiflora is native to the Americas, ranging from the Rio La Plata in Argentina north to the south/southeastern USA. In the USA, its range is primarily along the Atlantic coast and through the Gulf Coastal Plain (southeastern New York through Florida, westward to Texas) (McGregor et al., 1996). Recent reports of the plant from California and Washington indicate that its range may be expanding (Okada et al., 2009). Reports exist placing this species as present in Great Britain, although it is likely that these reports resulted from a misidentification of the species Ludwigia peploides (CEH, 2007). L. peploides is considered to be native to California, but Ludwigia peploides subsp. montevidensis is considered to be introduced.

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

L. grandiflora was introduced from the Americas to Montpellier in France in the 1830s, and has become one of the most widespread and detrimental aquatic invasive plants in that country (Ruaux et al., 2009). L. grandiflora subsp. hexapetala appeared in France at the end of the nineteenth century (Ruaux et al., 2009). In North America, L. grandiflora was introduced outside its native range into Tennessee and Kentucky where the first collections were made in 1968 and 1988, respectively. Introduction to California is referred to as ‘recent’ (Okada et al., 2009).

Introductions

Risk of Introduction

L. grandiflora is often used as an ornamental. Escape from cultivation likely explains its introduction beyond its native range. Its ability to spread rapidly through vegetative means coupled with a high degree of phenotypic plasticity (Ruaux et al., 2009) means the likelihood of establishment once the plant is released is high. L. grandiflora ramets collected from five populations in California, USA were genotypically identical, indicating that clonal reproduction explains the spread of the species in that region (Okada et al., 2009). As vegetative propagules are the most likely means of growth and expansion of the species, education and preventative measures should be targeted at pathways that might spread plant material.

Habitat

L. grandiflora is often found growing in freshwater wetlands, in slow-moving rivers and streams, on lake and reservoir shorelines and in shallow canals and on floodplains in California, USA (Okada et al., 2009). The plant displays a high degree of adaptability and flexibility in its habitat requirements due to its phenotypic plasticity (Ruaux et al., 2009). It is said to be highly tolerant of fluctuating water levels. In the interior portions of its range in the USA, the plant is found in three kinds of habitats: 1) emergent marshes and swamps in permanently pooled bottomland depressions that experience periodic flooding; 2) along shorelines and extending out into shallow bays; and 3) on sandy banks and gravel bars of shallow streams (Chester and Holt, 1990).

Habitat List

Hosts/Species Affected

Impacts on the local environment by L. grandiflora can be severe. The species possesses an allelopathic activity that changes water quality throughout the year and can lead to impoverished flora by decreasing seedling survival of vulnerable native taxa (Dandelot et al., 2008). L. grandiflora has been shown to cause severe hypoxia or even anoxia during summer months as well as leading to reduced sulphate and nitrate levels and increased sulphide and phosphate concentrations, leading to what Dandelot et al. (2005) refer to as ‘a dystrophic crisis’ and an intoxicated ecosystem.

Host Plants and Other Plants Affected

Growth Stages

Biology and Ecology

Genetics

Large-flowered variants of sect. Oligospermum have both hexaploid (2n = 48) and decaploid (2n = 80) forms, and this distinction forms the basis of their separation into the hexaploid L. grandiflora and the decaploid Ludwigia hexapetala. A polyploidy form (n = 48) has also been observed and was interpreted as a variant of L. grandiflora. Natural vigorous hybrids often form where the two species co-occur (2n = 8x = 64) (Zardini et al., 1991b).

Reproductive Biology

Clonal expansion is the primary means of reproduction for the species; stem fragments are spread by animals, humans, and water currents (Okada et al., 2009). Most populations flower, but sexual reproduction is likely of lesser importance than vegetative reproduction. Fruit formation in L. grandiflora is variable in French populations; the species is self-incompatible, but the species has a very high potential seed output (around 10,000 seeds per square metre) (Ruaux et al., 2009). In a study of locally-collected seed material from five populations in the middle Loire River in France, fruits had a buoyancy duration of approximately 11 weeks and fruits were frequently viable, indicating that although clonal expansion is the species’ primary means of reproduction, sexual reproduction may be an important means of survival and spread (Ruaux et al., 2009).

Physiology and Phenology

High levels of polymorphism and phenotypic plasticity have been reported for this species in France, which allows the species to grow in a wide range of environments (Ruaux et al., 2009). Its allelopathic properties mean it is an ecosystem engineer, and by making habitats unsuitable for native flora, it increases its competitive potential (Dandelot et al., 2008). It can reproduce vegetatively quite rapidly, but can also repopulate disturbed areas from seed banks. L. grandiflora is quite tolerant of fluctuations in water level and flooding.

Climate

Latitude/Altitude Ranges

Soil Tolerances

Soil drainage

• free
• impeded
• seasonally waterlogged

Natural enemies

Notes on Natural Enemies

The water primrose beetle Lysathia ludoviciana is relatively host-specific, and natural hosts include parrotfeather (Myriophyllum aquaticum), Ludwigia peploides and L. grandiflora (McGregor et al., 1996). The beetle is native to the southern USA and Caribbean region, and its USA distribution is reported to include Texas, Georgia, South Carolina, Ohio and Alabama (Habeck and Wilkerson, 1980). The chrysomelid Altica palustris has also been found in large numbers on L. grandiflora (Dauphin, 1997). Several genus-specific chrysomelid and curculionid beetles native to France may also target Ludwigia species (Gassmann et al., 2006). However, it is usually reported that the plant is generally avoided by herbivores and pathogens (Dandelot et al., 2008).

Means of Movement and Dispersal

Natural Dispersal

L. grandiflora disperses primarily through the movement of plant parts in water, although sexual reproduction and transportation of the resulting seeds may also be an important means of dispersal (Ruaux et al., 2009). Water currents can generate very high propagule pressure and water-mediated dispersal of stem fragments or floating mats can contribute both to population growth and invasive spread (Okada et al., 2009).

Vector Transmission

Stems can break off the plant and can be carried by animals to a new location, where they may establish new populations (IPAMS, 2009). No specific studies quantifying the propagule pressure due to biotic vector transmission have been conducted at this time.

Accidental Introduction

Humans may be the primary vector of transmission. L. grandiflora has been historically valued as an ornamental; ornamental plantings likely explain its introduction to Europe (Ruaux et al., 2009). Due to its presence in the horticultural trade, it is likely that propagules of this plant are occasionally present as hitchhikers, and included in orders of non-target species. It is possible that this plant may unintentionally be introduced in mixed-species planting orders.

Intentional Introduction

The bright yellow, rather showy flowers of L. grandiflora make it an interesting specimen for aquaculture. Additionally, the plant demonstrates a high degree of phenotypic plasticity, which allows it to adapt to a broad range of growing conditions and water regimes (Ruaux et al., 2009). Unfortunately, the very characteristics that make it a hardy and amenable garden specimen, also lend it the ability to invade a broad range of habitats. Ludwigia species spread through tropical, subtropical and temperate zones, and are very often invasive (Ruaux et al., 2009). This plant is still offered for sale through internet horticultural distributors. Its availability means that intentional introduction remains a significant risk. Current educational efforts aim to decrease the probability that this plant will be intentionally introduced, and will hopefully cut down on accidental release in areas where this plant has been declared a noxious weed.

Pathway Causes

Pathway Vectors

Impact Summary

Economic Impact

In California, USA dense stands of L. grandiflora reduce floodwater retention (Okada et al., 2009). The plant can also cause hyper-sedimentation and silting (Dandelot et al., 2008). L. grandiflora has naturalized in France and has cost millions of Euros (RAFTS, 2009). L. grandiflora is considered by some to cause the most damage of any invasive aquatic macrophyte in water ecosystems across many regions of France. In the northeast of France, it often achieves growth capable of blocking slow-moving waterways, interfering with navigation, impacting irrigation and drainage in lakes, ponds and ditches (Ruaux et al., 2009). The species’ physical and chemical alteration of the environment can cause severe damage to local ecosystems and biodiversity.

Environmental Impact

L. grandiflora can cause very severe environmental impacts. It gives off allelopathic elements that impact water quality throughout the year. Nuisance levels of the plant can lead to impoverished flora by decreasing seedling survival of vulnerable native taxa (Dandelot et al., 2008). L. grandiflora can manipulate dissolved oxygen concentrations, causing severe hypoxia or even anoxia during summer months. The plant also causes sulphate and nitrate levels to drop in favour of increased sulphide and phosphate concentrations, thus effecting what Dandelot et al. (2005) refer to as ‘a dystrophic crisis’ and an intoxicated ecosystem.

Impact: Biodiversity

Due to the species’ ability to shade out other submersed vegetation, it is generally considered a threat to biodiversity in its introduced range. Its allelopathic activity is detrimental to vulnerable native flora, as the chemical alterations the plant effects on the habitat contribute to decreasing seedling viability. There are threatened species in France that are highly susceptible to these impacts and that are placed at significant risk by L. grandiflora (Dandelot et al., 2005). Additionally the plant provides little in terms of suitable habitat or food source (IPAMS, 2009), and where invasive, can have far-reaching effects on multiple trophic levels (Dandelot et al., 2008).

Social Impact

This plant can cause substantial nuisance to recreational users by impeding navigation and interfering with hunting, fishing and other recreational activities (IPAMS, 2009) and can decrease the aesthetic value of waterbodies. Dense matting also prevents effective mosquito control (Okada et al., 2009).

Risk and Impact Factors

• Invasive in its native range
• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Highly adaptable to different environments
• Pioneering in disturbed areas
• Tolerant of shade
• Fast growing
• Has high reproductive potential
• Has propagules that can remain viable for more than one year
• Reproduces asexually
• Has high genetic variability

• Altered trophic level
• Damaged ecosystem services
• Ecosystem change/ habitat alteration
• Increases vulnerability to invasions
• Infrastructure damage
• Modification of hydrology
• Modification of natural benthic communities
• Modification of nutrient regime
• Modification of successional patterns
• Monoculture formation
• Negatively impacts human health
• Negatively impacts aquaculture/fisheries
• Reduced native biodiversity
• Threat to/ loss of endangered species
• Threat to/ loss of native species
• Transportation disruption

• Allelopathic
• Competition - monopolizing resources
• Competition - shading
• Competition - smothering
• Hybridization
• Rapid growth

• Highly likely to be transported internationally deliberately
• Difficult to identify/detect in the field
• Difficult/costly to control

Uses

Economic Value

The plant has attractive yellow flowers, is tolerant of a broad range of aquatic habitats and is very adaptable. These characteristics make it an interesting specimen for water gardening and means it is amenable to cultivation in a wide variety of situations.

Social Benefit

Water garden enthusiasts may have an aesthetic appreciation of this species. There might be some value in exploring the use of this species in wastewater treatment. Little other information is available regarding this species’ productive social use.

Environmental Services

Due to the plant’s phenotypic plasticity, it may provide some use in the reclamation of severely impacted ecosystems. However, its tendency toward invasiveness coupled with its allelopathic potential make this plant a poor candidate for restoration projects.

Uses List

General

• Botanical garden/zoo
• Pet/aquarium trade
• Sociocultural value

Similarities to Other Species/Conditions

L. grandiflora is very likely to be confused with other Ludwigia species. Zardini et al. (1991b) report that taxa of sect. Oligospermum are “notoriously difficult taxonomically; morphological distinctions between them are often not sharp”. The entire sect. Oligospermum is a polyploidy complex whose members form a very closely related group. L. grandiflora and Ludwigia hexapetala are known to hybridize where their ranges overlap, producing plants with intermediate characteristics (Nesom and Kartesz, 2000). Therefore, distinctions between them are slight, and often overlapping. Nesom and Kartesz (2000) report that plants with larger leaves and flowers and that are sparsely villous are L. hexapetala, whereas plants with smaller leaves and flowers and that are densely villous are L. grandiflora.

L. peploides stems grow more horizontally and their petals are usually 1.0-1.5 cm long, and anthers are 1.0-1.7 mm, whereas L. grandiflora and L. hexapetala stems grow vertically and have larger petals and anthers. Additionally, the small leaves at the base of the flower are triangular to egg-shaped in L. peploides, whereas those of L. hexapetala are ovate (EPPO, 2004).

Prevention and Control

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Prevention

L. grandiflora is valued as an ornamental, therefore educational programmes must be directed to educate the public about the dangers this plant poses outside its native range. Teaching users how to clean equipment in a way that decreases the chance of transmission is one way to lessen the impact of human-mediated transport.

Rapid Response

It is much easier and more effective to attempt to control this plant early in its introduction timeline. Small populations are effectively controlled by hand pulling, prior to significant clonal expansion.

Public Awareness

Numerous educational campaigns have been directed at informing the public about the danger of aquatic invasive species in countries in Europe to which L. grandiflora poses a threat. Governmental organizations disseminate educational materials about the identification and control of this species.

Control

Cultural Control and Sanitary Measures

As stem fragments are easily transportable, it is extremely important to decrease the instances of accidental introduction by addressing humans as a vector. By establishing guidelines on how to properly clean equipment, dispose of aquarium water, and identify target plants, it is likely that instances of accidental transportation and release will decrease. This species is widely available in the horticultural trade, therefore education and legislation should be targeted at addressing the threat of intentional introduction.

Physical/Mechanical Control

A number of physical control measures have been used to control L. grandiflora, including mechanical harvesters, rotovators and hand removal, but most of the results have been poor (IPAMS, 2009).

Movement Control

Plants can spread locally as seeds and fragments drift in water currents or are carried by wildlife, but most attention should be given to addressing forms of human-mediated transport.

Biological Control

Sterile grass carp, Ctenopharyngodon idella,has been used to control L. grandiflora (Manuel, 1989). However, grass carp are non-selective herbivores that will almost certainly harm native species. Some study of native biological control measures has revealed promise in using Lysathia beetles to control populations of the plant (McGregor et al., 1996), although no programmes are currently underway (IPAMS, 2009).

Chemical control

Control of L. grandiflora is possible with both spot and broadcast application of several herbicides. Broadleaf-selective auxinic 2,4-D and triclopyr can be used to minimize damage to monocots. Broad-spectrum herbicides glyphosate and imazapyr can also be used, as well as diquat for spot treatment (IPAMS, 2009).

References

Carretero JL, 1990. Additions to the Spanish exotic flora. Folia Botanica Miscellanea, 7:55-58.

CEH, 2007. Defra report. Defra report. Wallingford, UK: Center for Ecology and Hydrology, unpaginated.

Chester EW; Holt SE, 1990. Uruguayan water-primrose (Ludwigia uruguayensis) in Tennessee and Kentucky. Journal of the Tennessee Academy of Science, 45(1):9-12.

Dandelot S; Robles C; Pech N; Cazaubon A; Verlaque R, 2008. Allelopathic potential of two invasive alien Ludwigia spp. Aquatic Botany, 88(4):311-316. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T4F-4R9GGY9-2&_user=10&_coverDate=05%2F31%2F2008&_rdoc=7&_fmt=high&_orig=browse&_srch=doc-info(%23toc%234973%232008%23999119995%23683225%23FLA%23display%23Volume)&_cdi=4973&_sort=d&_docanchor=&_ct=14&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=840bccba60c7e7760705e2d50bdb6ff3

Dandelot S; Verlaque R; Dutartre A; Cazaubon A, 2005. Ecological, dynamic and taxonomic problems due to Ludwigia (Onagraceae) in France. Hydrobiologia, 551:131-136.

Dauphin P, 1997. Large numbers of Altica palustris (Weise) on Ludwigia grandiflora (Michaux). Bulletin de Liaison de l'Association des Coleopteristes de la Region Parisienne, 28:38.

EPPO, 2004. EPPO alert list. EPPO alert list. Paris, France: European and Mediterranean Plant Protection Organization, unpaginated.

Gassmann A; Cock MJW; Shaw R; Evans HC, 2006. The potential for biological control of invasive alien aquatic weeds in Europe: a review. Hydrobiologia [11th International Symposium on Aquatic Weeds 'Macrophytes in Aquatic Ecosystems: From Biology to Management', Moliets et Maâ, France, 2002.], 570:217-222.

GBIF, 2009. Global Biodiversity Information Facility. http://data.gbif.org/species/

Habeck DH; Wilkerson R, 1980. The life cycle of Lysathia ludoviciana (Fall) (Coleoptera: Chrysomelidae) on parrotfeather, Myriophyllum aquaticum (Velloso) Verde. Coleopterists Bulletin, 34(2):167-170

IPAMS, 2009. Invasive Plant Atlas of the MidSouth. Invasive Plant Atlas of the MidSouth. Mississippi, USA: GeoResources Institute, unpaginated.

Manuel KL, 1989. Proceedings of Workshop on Management of Aquatic Weeds and Mosquitoes in Impoudments March 14-15, Charlotte, North Carolina. Water Resources Research Institute, Report, 247. Water Resources Research Institute, University of North Carolina, 21-26.

McGregor MA; Bayne DR; Steeger JG; Webber EC; Reutebuch E, 1996. The potential for biological control of water primrose (Ludwigia grandiflora) by the water primrose flea beetle (Lysathia ludoviciana) in the Southeastern United States. Journal of Aquatic Plant Management, 34:74-76.

Nehring S; Kolthoff D, 2011. The invasive water primrose Ludwigia grandiflora (Michaux) Greuter & Burdet (Spermatophyta: Onagraceae) in Germany: first record and ecological risk assessment. Aquatic Invasions, 6(1):83-89. http://www.aquaticinvasions.net/2011/AI_2011_6_1_Nehring_Kolthoff.pdf

Nesom GL; Kartesz JT, 2000. Observations on the Ludwigia uruguayensis complex (Onagraceae) in the United States. Castanea, 65(2):123-125.

Okada M; Grewell BJ; Jasieniuk M, 2009. Clonal spread of invasive Ludwigia hexapetala and L. grandiflora in freshwater wetlands of California. Aquatic Botany, 91(3):123-129. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T4F-4W0WJ9Y-2&_user=10&_coverDate=10%2F31%2F2009&_rdoc=2&_fmt=high&_orig=browse&_srch=doc-info(%23toc%234973%232009%23999089996%231461076%23FLA%23display%23Volume)&_cdi=4973&_sort=d&_docanchor=&_ct=22&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=1e15adfd2024116a724e7258037d1cb3

RAFTS, 2009. Invasive Species and Biosecurity Programme. Invasive Species and Biosecurity Programme. Edinburgh, Scotland: Rivers and Fisheries Trusts of Scotland, unpaginated.

Ruaux B; Greulich S; Haury J; Berton JP, 2009. Sexual reproduction of two alien invasive Ludwigia (Onagraceae) on the middle Loire River, France. Aquatic Botany, 90(2):143-148. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T4F-4T8HHJ0-4&_user=10&_coverDate=02%2F28%2F2009&_rdoc=9&_fmt=high&_orig=browse&_srch=doc-info(%23toc%234973%232009%23999099997%23733055%23FLA%23display%23Volume)&_cdi=4973&_sort=d&_docanchor=&_ct=20&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=241218d13425483cea8ec378aed81f36

USACE-ERDC, 2009. Aquatic Plant Information System (APIS). Aquatic Plant Information System (APIS). Vicksburg, Mississippi, USA: United States Army Corps of Engineers - Engineer Research and Development Center, unpaginated.

USDA-ARS, 2009. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

Zamar MI; Hernández MC; Soto-Rodríguez GA; Retana-Salazar AP, 2013. A new Neotropical species of Liothrips (Thysanoptera: Phlaeothripidae) associated with Ludwigia (Myrtales: Onagraceae). Revista de la Sociedad Entomológica Argentina, 72(1-2):83-89. http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0373-56802013000100008

Zardini EM; Gu H; Raven PH, 1991. On the separation of two species within the Ludwigia uruguayensis complex (Onagraceae). Systematic Biology, 16(2):242-244.

Zardini EM; Peng CI; Hoch PC, 1991. Chromosome numbers in Ludwigia sect. Oligospermum and sect. Oocarpon (Onagraceae). Taxon, 40(2):221-230.

Distribution References

CABI, Undated. CABI Compendium: Status inferred from regional distribution. Wallingford, UK: CABI

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Links to Websites

Contributors

14/12/09 Original text by:

Alison Mikulyuk, Wisconsin Dept of Natural Resources, Science Operations Center, 2801 Progress Rd, Madison, WI 53716, USA

Distribution Maps