The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Limnobium Rich.

Common name: spongeplant

Synonyms and Other Names: Hydromystria G. Meyer; Jalambicea Cervantes; Rhizakenia Rafinesque; Trianea H. Karsten

Taxonomy: available through www.itis.govITIS logo

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
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

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.

StateYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
California1996201712Clear Creek-Sacramento River; Honcut Headwaters-Lower Feather; Lower Sacramento; Lower San Joaquin River; Mad-Redwood; Mattole; Middle San Joaquin-Lower Chowchilla; San Francisco Bay; San Joaquin Delta; Santa Ana; Suisun Bay; Tulare Lake Bed
Nevada200720072Lake Tahoe; Upper Carson
New York182820142Irondequoit-Ninemile; Lake Ontario
Washington201620181Willapa Bay

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.

Author: McLaurin, C.S., and R.M. Wersal

Revision Date: 10/11/2018

Citation Information:
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.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2019]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [11/17/2019].

Contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co-authorship if warranted. For queries involving fish, please contact Matthew Neilson. For queries involving invertebrates, contact Amy Benson.