Identification: According to Godfrey and Wooten (1981):
Habit: Perennial, floating and emergent, herbaceous forb
Stem/roots: non-flowering, sprawling stems float along the water surface with roots at the stem nodes; upright stems freely branching and flowering; pubescent
Leaves: alternating leaves on floating stems are spatulate (spoon-shaped), petiolate (leaf stems), and have rounded apices; alternating leaves on upright stems are lanceolate (lance-shaped), mostly sessile, and have acute apices; pubescent
Flowers: solitary flowers at leaf axils of upright stems; pedicels 1-5 cm, usually confused with floral tubes; a pair of small bractlets indicate the separation of the pedicel and floral tube; pedicel and floral tube pubescent; calyx of 5, sometimes 6, acute sepals, 10-12 mm, pubescent on the outside; corolla of 5, sometimes 6, bright yellow, rounded petals, 1-2 cm long and wide; stamens 8-12, twice the amount of sepals/petals
Fruits: fruit a pubescent, cylindric capsule 1-2.5 cm long, 3-4 mm wide
Look-alikes: Many Ludwigia species have similar leaves and flowers, but those two organs are key to determining identity. The alternate leave arrangement, the 8-12 stamens, and the 5-6 petals differentiate to about four species. The Ludwigia uruguayensis species complex includes L. grandiflora and L. hexapetala. Leaves on upright stems will be mostly lanceolate (widest portion of the leaf in the leaf center) on L. grandiflora and mostly oblanceolate (widest portion of the leaf in the top half of the leaf) on L. hexapetala, and stem nodes are swollen along the lower portion of upright stems on L. hexapetala (Colette Jacono, Univ. of Florida, pers. comm. 2017). Upright stems of L. grandiflora have pubescent stems, leaves, and floral tubes, distinguishing them from L. peploides, which are mostly glabrous (hairless) and lack upright stems. Floral tubes/capsules of L. grandiflora are narrower and longer than those of L. peruviana, which have stout and pyramidal floral tubes/capsules. The native L. leptocarpa has smaller petals (<1 cm) than those of L. grandiflora (>1 cm), usually the same length as the sepals.
† Populations may not be currently present.
* HUCs are not listed for states where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).
Life history: self-compatible flowers will self-fertilize; most reproduction is through vegatative fragmentation of stems; flowers from April to September; seeds remain embedded in woody capsules (Okada et al. 2009; Les 2018)
Habitat: marshes, swamps, ponds, lakes, ditches, canals, and wet disturbed areas (Godfrey and Wooten 1981; Les 2018)
Tolerances: fresh to brackish (0-3.5 ppt salinity); pH 6.1-7.3; depths to 2.4 m; elevations to 102 m; poorly drained muck and sandy clay; fire-, flood-, graze-, and mow- tolerant over short periods (Les 2018)
Community interactions: pollinated by generalists (bees, butterflies, and flowerflies); waterfowl consume the seeds of L. grandiflora; Lysathia ludoviciana leaf beetles consume the foliage of L. grandiflora (Les 2018)
Impact of Introduction:
Summary of species impacts derived from literature review. Click on an icon to find out more...
Ludwigia grandiflora creates large homogenous mats that outcompete other organisms for essential resources, such as light, nutrients, and open water habitat for waterfowl (Nehring and Kolthoff 2011, Stiers et al. 2011, Grewell et al. 2016). Invertebrate richness and abundance declined in ponds with high abundance of L. grandiflora due to increased decomposition and decreased dissolved oxygen (Stiers et al. 2011). However, pollinator densities increased in communities with L. grandiflora, but native plant species richness, especially submerged plants, declined due to decreased sunlight availability and oxygen exchange (Stiers et al. 2011, Stiers et al. 2014). Through allelopathic chemicals, L. grandiflora inhibited Lactuca sativa and Nasturtium officinale germination when grown in mixtures (Dandelot et al. 2008).
References: (click for full references)
Dandelot, S., C. Robles, N. Pech, A. Cazaubon, and R. Verlaque. 2008. Allelopathic potential of two invasive alien Ludwigia spp. Aquatic Botany 88:311-316.
Godfrey, R.K., and J.W. Wooten. 1981. Aquatic and Wetland Plants of the Southeastern United States, dicotyledons. University of Georgia, Athens, GA.
Grewell, B.J., M.D. Netherland, and M.J. Skaer Thomason. 2016. Establishing research and management priorities for invasive water primroses (Ludwigia spp.). U.S. Army Corps of Engineers, Engineer Research and Development Center, Vicksburg, MS. https://apps.dtic.mil/sti/pdfs/AD1002917.pdf.
Les, D.H. 2018. Aquatic dicotyledons of North America: ecology, life history, and systematics. CRC Press, Boca Raton, FL.
Nehring, S. and D. Kolthoff. 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. https://doi.org/10.3391/ai.2011.6.1.10.
Nesom, G.L. and J.T. Kartesz. 2000. Observations on the Ludwigia uruguayensis complex (Onagraceae) in the United States. Castanea. 65(2): 123-125.
Okada, M., B. Grewell, M. Jasieniuk. 2009. Clonal spread of invasive Ludwigia hexapetala and L. grandiflora in freshwater wetlands of California. Aquatic Botany 91:123-129.
Stiers, I., N. Crohain, G. Josens, and L. Triest. 2011. Impact of three aquatic invasive species on native plants and macroinvertebrates in temperate ponds. Biological Invasions 13:2715-2726. https://doi.org/10.1007/s10530-011-9942-9.
Stiers, I., K. Coussement, and L, Triest. 2014. The invasive aquatic plant Ludwigia grandiflora affects pollinator visitants to a native plant at high abundances. Aquatic Invasions 3:357-367.
Wagner, W.L., P.C Hoch and P.H. Raven 2007. Systematic Botany Monographs: Revised Classification of the Onagraceae. 83: 243 pp.
Zardini, E. M., H. Gu & P. H. Raven 1991. On the separation of two species within the Ludwigia uruguayensis complex (Onagraceae). Systematic Botany. 16(2): 242–244.
Zardini, E.M., H. Gu, and P.H. Raven. 1992. Erratum: on the separation of two species within the Ludwigia uruguayensis complex (Onagraceae). Systematic Botany. 17(4): 692.
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.