Synonyms and Other Names: Jussiaea grandiflora L., Jussiaea hirta, Jussiaea macrocarpa, Jussiaea peruviana, Jussiaea speciosa, Jussiaea sprengeri, Ludwigia hirta, Oenothera hirta
Peruvian seedbox, Peruvian primrose-bush, primrose bush, primrose willow, water primrose
Identification: According to Long and Lakela (1971), Godfrey and Wooten (1981), and Nelson (1996):
Habit: shrubby perennial forb; semi-aquatic
Stems/Roots: heavily branched; typically dark green or brown; woody lower stems with herbaceous and copiously pubescent upper stems, especially on younger stems; lower stems can grow to a diameter of 3-4 cm in one season; woody, dominant root, with laterals emerging out near the surface
Leaves: narrow and elliptic (lanceolate to ovate lanceolate), alternating leaves, rarely opposite, 5-15 cm long and 1-3 cm wide; both surfaces are pubescent
Flowers: solitarily, perfect (both male and female); 4 sepals (8-12 mm long); 4, rarely 5, yellow rounded petals (1-3 cm long and wide)
Fruits/Seeds: fruits are short, stout, four-angled capsules, 1-3 cm long; seeds are buff to light brown, elliptical or oblong, and usually between 0.3 to 0.8 mm long
Look-a-likes: Ludwigia octovalvis and L. leptocarpa are often misidentified as L. peruviana in the field. However L. leptocarpa and L. octovalvis have much longer and narrower capsules than L. peruviana.
Life history: About 80% of L. peruviana's biomass is above-ground, and roughly 20% of above-ground biomass comes from its leaves (Jacobs et al., 1993). Reproduction occurs by seed or vegetatively using suckers from submerged stems and/or stem fragments. Ludwigia peruviana produces many seeds of which 99% are viable, and can have a soil seed bank of roughly 65,000/m2 (Jacobs et al., 1993; Jacobs et al., 1994). Ludwigia peruviana seeds are hydrophobic allowing for underwater germination, and seedlings eventually float to the surface, forming floating islands (Jacobs et. al. 1993; Chandrasena 2005). Within two years, L. peruviana produces flowers (Chandrasena, 2005).
Habitat: Shallow water in ditches and canals, as well as marshy areas (Godfrey and Wooten, 1981; Nelson, 1996).
Tolerances: Ludwigia peruviana prefers higher elevations and suffers near man-made structures (Iacona et al., 2015). Ideal light levels are between 60-75% incident light. Ludwigia peruviana does not perform well in saline conditions (Jacobs et al., 1993). When salt reaches 0.2 M, seeds will no longer germinate. Seeds covered with more than 2 cm of soil will likely not germinate (Jacobs et al., 1993). Ludwigia peruviana senesces in extreme cold (Godfrey and Wooten, 1981). Lateral roots form white spongy vertical pneumatophores in shallow water to adapt to anoxic conditions (Parsons and Cuthbertson 2001; Ellmore 1981).
Community interactions: Birds that nest in wetlands can spread Ludwigia peruviana seeds long distances (Barua et al., 2017). Wet L. peruviana seeds also adhere themselves to feathers, but fall off when dry (Jacobs et al., 1994). Ducks are known to eat introduced L. peruviana (Parsons and Cuthbertson 2001).
Means of Introduction:
While it is unsure how L. peruviana was introduced in the Unites States, it was likely introduced in many parts of the world for ornamental uses and as botanical specimens. It continures to spread via its many, highly viable, seeds as well as from stem fragments (Chandrasena 2005; Parsons and Cuthbertson 2001). When the stems of the plant break off, new shoots can grow from the fragments (Jacobs et al., 1994). Ludwigia peruviana can also spread its seed via water runoff (Barua et al., 2017). Tiny seeds of L. peruviana are commonly transported on the feathers of birds or unknowingly through human clothing, hats, and hair (Jacobs et al. 1994).
Established throughout Florida and southern Georgia (Godfrey and Wooten, 1981) but is common south of Gainesville, FL (Nelson, 1996).
Impact of Introduction:
Ludwigia peruviana’s dense growth can interfere with the natural flow of waterways and blocks most light (Chandrasena, 2005). Choked water flow and increased sedimentation has been observed in interconnected waterways as a result of L. peruviana’s dense stands (Chandrasena 2005). Ludwigia peruviana has grown in ponds to the point that 70% of the surface was covered, which affected water flow (Chandrasena, 2005).
Ludwigia peruviana can impact the ecological diversity of the flora and fauna in surrounding wetlands (Chandrasena 2005). When established, L. peruviana has resulted in decreased biodiversity among aquatic plants and has reduced bird populations (Chandrasena, 2005; Jacobs et al., 1994). In the Kissimmee floodplain, the species is the dominant canopy cover, displacing native plants and reducing plant diversity, despite efforts to restore native broadleaf marsh plants (Toth 2010a; Toth 2010b).
References: (click for full references)
Barua, I.C., J. Deka, M. Devi, R.L. Deka, and J. Moran. 2017. Weeds as Emerging Threat to Biodiversity:A Consequence of Spread of Ludwigia peruviana in Dhansiri and Kopili Catchment Areas of Assam, North East India: Current Science, v. 112, no. 09, p. 1904.
Chandrasena, N. 2005. Ludwigia peruviana (L.) Hara and Ludwigia longfolia (DC) Hara In Sydney: From Immigrants to Invader: p. 11.
Chandrasena, N., L. Pinto, and R. Sim. 2002. Reclaiming Botany Wetlands, Sydney through integrated management of Ludwigia peruviana and other weeds. Pages 134-137 in Proceedings of the 13th Australian Weeds Conference. Perth, Australia.
Dike, I.P., O.O. Obembe, and F.E. Adebiyi. 2012. Ethnobotanical survey for potential anti-malarial plants in south-western Nigeria: Journal of Ethnopharmacology, v. 144, no. 3, p. 618–626.
Godfrey, R.K., and J.W. Wooten. 1981. Aquatic and Wetland Plants of Southeastern United States Dicotyledons: The University of Georgia Press.
Ellmore, G.S. 1981. Root dimorphism in Ludwigia peploides (Onagraceae): structure and gas content of mature roots. American Journal of Botany 68(4):557-568. https://www.jstor.org/stable/2443032.
Iacona, G., F.D. Price, and P.R. Armsworth. 2015. Predicting the presence and cover of management relevant invasive plant species on protected areas | Elsevier Enhanced Reader, accessed January 14, 2020, at https://doi.org/10.1016/j.jenvman.2015.10.052.
Jacobs, S.W.L., F. Perrett, M. Brock, K.H. Bowmer, G. McCorkelle, J. Rawling, J. Stricker, and G.R. Sainty. 1993. Ludwigia peruviana - description and biology.: Proceedings I of the 10th Australian Weeds Conference and 14th Asian Pacific Weed Science Society Conference, Brisbane, Australia, 6-10 September, 1993, p. 225–228.
Jacobs, S.W.L., F. Perrett, G.R. Sainty, K.H. Bowmer, and B.J. Jacobs. 1994. Ludwigia peruviana (Onagraceae) in the Botany Wetlands near Sydney, Australia: Marine and Freshwater Research, v. 45, no. 8, p. 1481–1490.
Long, R.W., and O. Lakela. 1971. A Flora of Tropical Florida: University of Miami Press.
Nelson, G., 1996, The Shrubs & Woody Vines of Florida: A Reference and Fielf Guide: Pineapple Press.
Parsons, W.T., and E.G. Cuthbertson. 2001. Noxious Weeds of Australia. Second edition. Csiro Publishing. https://www.google.com/books/edition/Noxious_Weeds_of_Australia/sRCrNAQQrpwC?hl=en&gbpv=1.
Toth, L.A. 2010a. Unrealized expectations for restoration of a floodplain plant community. Restoration Ecology 18(6):810-819.
Toth, L.A. 2010b. Restoration response of relict broadleaf marshes to increased water depths. Wetlands 30(2):263-274.
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.