Common name: spongeplant
Synonyms and Other Names: Hydromystria G. Meyer; Jalambicea Cervantes; Rhizakenia Rafinesque; Trianea H. Karsten
available through www.itis.gov
Identification: As per Baldwin et al. (2012):
Habit: perennial, floating forb
Roots/Stem: rooted in substrate when stranded; stolons floating
Leaves: petioled; emergent or floating; spongy tissue (aerenchyma) on underside (abaxial) of floating leaves; blades ovate to round; bases reniform to cordate
Flowers: inflorescence a cyme; little or no peduncle; monoecious; emergent; pedicelled; sepals 3; petals 3, green to yellow; stamens 9-12; filaments fused; stigmas 6-18, longer than petals and sepals
Fruits/Seed: fleshy, ellipsoid to spheric berry with ellipsoid, spiny seeds
Look-a-likes: Emergent and floating leaves of Heteranthera limosa, Heteranthera reniformis, Eichhornia crassipes, Hydrocleys nymphoides, young Nymphaea spp., and Hydrocharis morsus-ranae all lack the spongy tissue on the underside of the floating leaves of Limnobium. The stigmas extending longer than the petals on female flowers of Limnobium are characteristic.
Size: 1-10 cm wide, 1-15 cm tall (Baldwin et al. 2012)
Native Range: Limnobium is native to North, Central, and South America and the islands of the West Indies.
Hydrologic Unit Codes (HUCs) Explained
Puerto Rico &
Interactive maps: Point Distribution Maps
Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Limnobium are found here.
Table last updated 9/30/2019
† Populations may not be currently present.
Ecology: Life history: Dispersal is through seed production and vegetative spread via stolon growth (Akers pers. comm.).
Limnobium tends to be found in shallow, slow-moving backwaters, lagoons, swamps, ponds, lakes, and marshes, but can occur along the edges of faster-moving rivers and streams. To date, little is know about this species basic biological and ecological life history traits. The seedling stage of this plant can be readily mistaken for common duckweed.
Means of Introduction: Limnobium is widely available through aquarium and nursery mail-order. This species likely escaped from private or commercial waters where it was used as an ornamental planting. Spread from waterbody to waterbody will be facilitated by the seedling’s small size.
Status: Populations are either failed or extirpated in the northeast U.S.
California, Nevada, and Washington populations are likely established.
Impact of Introduction: Limnobium is considered a very vigorous competitor, and is resilient to management efforts (Hrusa 2002). Currently, economic and environmental impacts are unknown due to its limited spread, but are thought to be much like the effects of other floating invasive species, such as waterhyacinth. Limnobium is expected to affect waterways much more negatively than waterhyacinth, given that L. mats are much more compact and dense than waterhyacinth mats, and L. grows twice as fast as waterhyacinth (Akers pers. comm.). Impacts to aquatic systems include lower dissolved oxygen levels beneath plant mats, higher organic matter loading rates, and altered pH levels (Mallison 2001). These mats will also impede navigation and recreation by blocking access to waterways and hindering fishing and swimming. In addition, L. spongeplant will be very detrimental to irrigation by reducing the flow rate through canals and ditches.
References: (click for full references)
Baldwin, B.G., D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken. 2012. The Jepson Manual: Vascular Plants of California. 2nd edition. University of California Press, Berkeley and Los Angeles, CA.
Hrusa, F., B. Ertter, A. Sanders, G. Leppig and E. Dean. 2002. Catalogue of non-native vascular plants occurring spontaneously in California beyond those addressed in The Jepson Manual: Part I. Madrono, 49(2), 61-98.
Lowden, R.M. 1992. Floral variation and taxonomy of Limnobioum l. L.C. Richard (Hydrocharitaceae). Rhodora, 94(878), 111-134.
Mallison, C.T., R.K. Stocker and C.E. Cichra. 2001. Physical and vegetative characteristics of floating islands. Journal of Aquatic Plant Management, 39, 107-111.
McLaurin, C.S., and R.M. Wersal
Revision Date: 10/11/2018
McLaurin, C.S., and R.M. Wersal, 2019, Limnobium Rich.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=1112, Revision Date: 10/11/2018, Access Date: 11/17/2019
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.