Primrose Willow (Ludwigia peruviana)

Present distribution

Scientific name:	Ludwigia peruviana (L.) H. Hara
Common name(s):	Primrose Willow, Primrose Lily, Ludwigia

This weed is not known to be naturalised in Victoria

Habitat:

Reported in shallow, still to slow moving streams and wetlands, on wet marshy soils, creek banks and drying muds, it may however be susceptible to completely drying out (Jacobs et al 1994; Parsons & Cuthbertson 2001). It can also form floating vegetation islands in deeper water (Jacobs et al 1994).

Potential distribution

Potential distribution produced from CLIMATE modelling refined by applying suitable landuse and vegetation type overlays with CMA boundaries

Map Overlays Used

Land Use:

Broad vegetation types
Swamp scrub; Freshwater wetlands; 10m River and 5m Creek Buffer; Canals 3m major, 2m minor.

Colours indicate possibility of Ludwigia peruviana infesting these areas.

In the non-coloured areas the plant is unlikely to establish as the climate, soil or landuse is not presently suitable.

map showing the potential distribution of primrose willow

Red= Very high	Orange = Medium
Yellow = High	Green = Likely

Impact

QUESTION	COMMENTS	RATING	CONFIDENCE
Social
1. Restrict human access?	Can restrict the movement of boats and limit the use of areas for recreational and navigational activities (Parsons & Cuthbertson 2001). Therefore major impediment to the use of waterways.	h	mh
2. Reduce tourism?	Impacts upon water based recreational activities (Parsons & Cuthbertson 2001).	h	mh
3. Injurious to people?	Unknown.	m	l
4. Damage to cultural sites?	May have a significant effect on the aesthetics of areas near riparian or wetland vegetation.	ml	l
Abiotic
5. Impact flow?	Can considerably reduce flow (Parsons & Cuthbertson 2001). The plant can vary in its impact as it can be free floating, forming vegetation islands, however in water to 1.5m it can grow to 4m tall as an attached emergent (Jacobs et al 1994).	h	h
6. Impact water quality?	No specific evidence reported. However as it reduces water flow and increases biomass, cycling of carbon dioxide and oxygen could be altered, and as it is a deciduous species, leaf fall in autumn could alter the nutrient cycling of a wetland system (Jacobs et al 1994).	m	l
7. Increase soil erosion?	Reported to reduce water flow (Parsons & Cuthbertson 2001). This could exacerbate flooding events.	ml	m
8. Reduce biomass?	Can produce a standing crop of ~ 1.5kg dry weight m^-2 (Jacobs et al 1994). The species causes problems through excessive growth in previously more open wetland systems (Parsons & Cuthbertson 2001).	l	mh
9. Change fire regime?	Aquatic plant, therefore not exposed to fire.	l	m
Community Habitat
10. Impact on composition (a) high value EVC	EVC= Sedge Wetland (V); CMA= West Gippsland; Bioreg= Gippsland Plain; VH CLIMATE potential. Can crowd out native species and form a monoculture (Jacobs et al 1994).	h	h
(b) medium value EVC	Aquatic species. All Victorian water bodies considered to comprise high value EVCs only (Weiss pers. com).	l	mh
(c) low value EVC	Aquatic species. All Victorian water bodies considered to comprise high value EVCs only (Weiss pers. com).	l	mh
11. Impact on structure?	This plant can crowd out native aquatics and form monocultures (Jacobs et al 1994).	h	h
12. Effect on threatened flora?	No specific evidence.	mh	l
Fauna
13. Effect on threatened fauna?	Bird populations have been reported to have diminished (Jacobs et al 1994). No specific species were reported however.	mh	m
14. Effect on non-threatened fauna?	Bird populations have been reported to have diminished, due to the change in wetland habitat (Jacobs et al 1994).	mh	h
15. Benefits fauna?	Ducks have been reported to readily eat the fruits and seeds (Parsons & Cuthbertson 2001).	mh	mh
16. Injurious to fauna?	No evidence reported.	m	l
Pest Animal
17. Food source to pests?	Few species reported to use the species as a food source and no specific pest species have been reported.	l	m
18. Provides harbour?	May increase available mosquito habitat, like Myriophyllum aquaticum (Bossard, Randell & Hoshovsky 2000).	ml	m
Agriculture
19. Impact yield?	No evidence of this reported.	l	m
20. Impact quality?	No evidence of this reported.	l	m
21. Affect land value?	No evidence of this reported.	l	m
22. Change land use?	No evidence of this reported.	l	m
23. Increase harvest costs?	Limits the use of streams for watering stock (Parsons & Cuthbertson 2001). Therefore a watering system of pumps and troughs may need to be put into place. Can grow in irrigation canals, restricting water flow and possibly foul pumps etc.	m	mh
24. Disease host/vector?	No evidence of this reported.	l	m

Invasive

QUESTION	COMMENTS	RATING	CONFIDENCE
Establishment
1. Germination requirements?	Seeds readily germinate in spring (Parsons & Cuthbertson 2001).	mh	mh
2. Establishment requirements?	Aquatic species, requiring sufficient water to establish, however this does not require specific events of flooding or drying out. Plants can establish on floating vegetation in deep water of on the bottom in shallow water, however germination can be suppressed by 100% shade, however up to 80% of seeds can germinate with only 10% of full sun (Jacobs et al 1994). Therefore the species can establish without additional factors.	h	h
3. How much disturbance is required?	Reported as an invader of disturbed wetlands (Jacobs et al 1994). Unknown specifically how much disturbance is required.	m	mh
Growth/Competitive
4. Life form?	An aquatic shrub (Parsons & Cuthbertson 2001).	h	mh
5. Allelopathic properties?	None described.	l	m
6. Tolerates herb pressure?	Disturbance which creates broken stem fragments can aid vegetative dispersal. It is eaten by some duck species, however in Australia to prevent expansion control with herbicide is required (Chandrasena, Pinto & Sim 2002; Parsons & Cuthbertson 2001).	mh	mh
7. Normal growth rate?	Has rapid growth in summer (Parsons & Cuthbertson 2001). Able to out-compete other native aquatics (Chandrasena, Pinto & Sim 2002; Jacobs et al 1994).	h	h
8. Stress tolerance to frost, drought, w/logg, sal. etc?	Aquatic species tolerant of waterlogging. It can even establish as floating vegetation islands and during flooding events mature plants can be detached as dispersed (Jacobs et al 1994). A deciduous species this shows and adaptation to cold and frost tolerance (Jacobs et al 1994). May be susceptible to drying out (Drought) (Jacobs et al 1994). Only reported in freshwater systems, may therefore be susceptible to salinity. Aquatic species occurs in an area protected from fire.	mh	mh
Reproduction
9. Reproductive system	Produces seed and can reproduce vegetatively (Jacobs et al 1994).	h	h
10. Number of propagules produced?	An estimated average seed production of ~40,000 seeds per stem has been reported for plants in wetlands near Sydney (Jacobs et al 1994).	h	h
11. Propagule longevity?	Any dormancy the seeds may have appears to be broken within 2-3 years (Jacobs et al 1994).	l	h
12. Reproductive period?	Can form monocultures (Jacobs et al 1994)	h	h
13. Time to reproductive maturity?	Flowering does not usually occur until the second year (Jacobs et al 1994).	mh	h
Dispersal
14. Number of mechanisms?	Vegetative propagules and detached plants can be dispersed by water (Jacobs et al 1994). Seeds float and therefore can also be readily dispersed by water, can also attach to waterfowl (Jacobs et al 1994).	h	h
15. How far do they disperse?	Water is capable of dispersing propagules distances of more than 1km. Some seeds can work their way between feathers and therefore not be removed until the birds next preening which may be the next wetland stop (Jacobs et al 1994).	h	h

References

Chandrasena N., Pinto L. & Sim R., 2002, Reclaiming Botany Wetalands, Sydney through integrated management of Ludwigia peruviana and other weeds. Thirteenth Australian Weeds Conference, Papers & Proceedings. 134-137.

Jacobs S.W.L., Perrett F., Sainty G.R., Bowmer K.H. & Jacobs B.J., 1994, Ludwigia peruviana (Onagraceae) in the Botany Wetlands near Sydney, Australia. Australian Journal of Marine and Freshwater Research. 45: 1481-1490.

Parsons W.T. & Cuthbertson E.G. 2001, Noxious weeds of Australia, 2nd ed., CSIRO Publishing, Collingwood.

Weiss, J. Project Leader, Pest Plant Impact Assessment. DPI, Frankston. Tel 9785 0111. (11/07/03)

Global present distribution data references

Australian National Herbarium (ANH) 2007, Australia’s Virtual Herbarium, Australian National Herbarium, Centre for Plant Diversity and Research, viewed 16 Jan 2007, http://www.anbg.gov.au/avh/

Global Biodiversity Information Facility (GBIF) 2007, Global biodiversity information facility: Prototype data portal, viewed 16 Jan 2007, http://www.gbif.org/

Jacobs S.W.L., Perrett F., Sainty G.R., Bowmer K.H. & Jacobs B.J., 1994, Ludwigia peruviana (Onagraceae) in the Botany Wetlands near Sydney, Australia. Australian Journal of Marine and Freshwater Research. 45: 1481-1490.

Kumar V.S. & Sreekumar P.V., 2000, Ludwigia peruviana (L.) Hara – A shrub new to Andamans. Journal of Economic & Taxonomic Botany. 24: 276-278.

Missouri Botanical Gardens (MBG) 2007, w³TROPICOS, Missouri Botanical Gardens Database, viewed 15 Jan 2007, http://mobot.mobot.org/W3T/Search/vast.html

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