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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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Common name: roundleaf toothcup

Synonyms and Other Names: rotala, dwarf rotala

Taxonomy: available through www.itis.gov

Identification: Rotala rotundifolia (Buch.-Ham. ex Roxb.) Koehne is a tropical to sub-tropical perennial plant with considerable phenotypic plasticity.  The plant can grow as an obligate aquatic, with one growth form, or as a semi-aquatic with a very different growth form (heterophyllous) (Karatas et al. 2014).

The submersed aquatic leaves are thin, lanceolate, and up to 2 cm long.  Leaf surfaces of submersed leaves are dark green, grey or reddish in color, underside of leaves are red or purple.  Leaves are decussate (arranged in opposite pairs at right angles to those above or below).  Emergent leaves are broadly ovoid (rounded) attaching directly to the stem or with a short petiole and bright-green in color.  Stems are soft, succulent, dark pink or purplish in color and abundantly branched.  Copious rose colored flowers are produced in dense clusters on terminal, aerial spikes, called racemes.  Fruit are small capsules (1-2 mm long) that split along sides releasing viable seeds (Cook 1976; Gettys and Della Torre 2014; Karatas et al. 2014).

Emergent R. rotundifolia establishes along shorelines and into associated wetlands rarely growing more than 15 cm in height, while submersed plants grow in tight, dense colonies more than 2 meters high reaching the water surface where the plant grows to thick surface mats (Gettys and Della Torre 2014).

Size: 15-200 cm height depending on light penetration (Gettys and Della Torre 2014)

Native Range: Rotala rotundifolia originates from southeast Asia, southern India, and Japan (Cook 1976).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Historically native to India, but has spread as far north as the Caspian Sea, where it can survive mean winter temperatures of 4°C.  This species can potentially establish and flourish in many areas of the southern continental US, western states and in the tropical territories of Guam, Puerto Rico and the Virgin Islands if introduced (Ervin and White 2007).

Rotala rotundifolia is widely available through the international aquarium plant trade. Aquarium and pond plant publications note the ease of propagation with this species, recommending planting of cut or trimmed tops into suitable substrate or simply through the natural creeping growth habit of the plant.

Means of Introduction: It has been well received in the water garden trade for its brilliant, rose colored flowers and lush, creeping perennial growth.

Status: Currently established in south Florida (Wunderlin and Hansen 2008), but likely eradicated in Alabama (Ervin and White 2007). Status is unknown in Mississippi, though the population is possibly contained from spreading further downstream of the Flint Creek Reservoir due to high salinity (Carl Della Torre, UF/IFAS, pers. comm.).

Impact of Introduction:

Summary of species impacts derived from literature review. Click on an icon to find out more...

Ecological	Economic

In its native range, R. rotundifolia is a common weed in rice paddies.  The plant spreads vegetatively from stem fragments, which form adventitious roots at nodes and also spreads from dispersed seeds (Ervin and White 2007).  Rotala rotundifolia can produce extremely dense submersed communities and large thick floating mats, creating conditions that shade other submersed aquatic plants and restrict navigation and water flow in drainage and irrigation canals.  Plants that break loose can build up at downstream structures, including bridge pilings.

Remarks: Rotala rotundifolia is used in its native range as a medicinal plant.  The species is known for its anti-pyretic, detoxication, anti-swelling, and diuresis properties.  Also used in treatment of cirrhosis, gonorrhea, menstrual cramps and piles in China (Karatas et al. 2014).

References: (click for full references)

Burks, K.C., V.V. Vandiver, Jr., D.W. Hall, and C.C. Jacono. 2003. Rotala rotundifolia (Lythraceae) new to Florida. SIDA, Contributions to Botany 20(4):1765-1769.

Cook, C.D.K. 1976. A revision of the genus Rotala. Boissiera 29(1):1-156.

Center for Invasive Species and Ecosystem Health. 2015. EDDMapS: Early detection and distribution mapping system. The University of Georgia, Tifton, GA. http://www.eddmaps.org.

Ervin, G.N., and R.A. White. 2007. Assessing vegetative growth potential of exotic Rotala rotundifolia (Roxb.) Koehne (roundleaf toothcup), in comparison with Alternanthera philoxeroides (Mart.) Griseb. (alligator weed), a known successful invader. Department of Biological Sciences, Mississippi State University, Mississippi State, MS.

Gettys. L. 2015. Lookalike aquatic plants. Aquatics 37(2):15-23. http://www.fapms.org/aquatics/issues/2015summer.pdf.

Gettys, L.A., and C.J. Della Torre, III. 2014. Rotala: a new aquatic invader in southern Florida. University of Florida IFAS Extension, Gainesville, FL. http://edis.ifas.ufl.edu/.

Jacono, C.C., and V.V. Vandiver. 2007. Rotala rotundifolia – purple loosestrife of the South? Aquatics 29(1):4,6,8-9. http://www.fapms.org/aquatics/issues/2007spring.pdf.

Karatas, M., M. Aasim, and M. Çiftçioglu. 2014. Adventitious shoot regeneration of roundleaf toothcup-Rotala rotundifolia [(Buch-Ham. ex Roxb) Koehne]. The Journal of Animal & Plant Sciences 24(3):838-842.

Madsen J.D. 2010. Invasive Plant Atlas of the MidSouth. Geosystems Research Institute, Mississippi State University, Starkville, MS. http://www.gri.msstate.edu/ipams/.

Reese, N.L. and R.R. Haynes. 2002. Noteworthy collections: Alabama. Castanea 67(2):216. http://www.jstor.org/stable/pdf/4034198.pdf.

University of Florida Herbarium. 2016. Florida Museum of Natural History. University of Florida, Gainesville, FL. http://www.flmnh.ufl.edu/herbarium/.

Wunderlin, R.P., and B.F. Hansen. 2008. Atlas of Florida Vascular Plants. [S. M. Landry and K. N. Campbell (application development), USF Water Institute.] Institute for Systematic Botany, University of South Florida, Tampa, FL. http://florida.plantatlas.usf.edu/.

Other Resources:
Rotala rotundifolia - UF/IFAS Center for Aquatic and Invasive Plants

Plants Rescue - dwarf rotala

Author: Thayer, D.D., I.A. Pfingsten, and C.C. Jacono

Peer Review Date: 2/24/2016

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.