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.

Bacopa repens
Bacopa repens
(creeping waterhyssop)

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Bacopa repens (Sw.) Wettst.

Common name: creeping waterhyssop

Synonyms and Other Names: Gratiola repens SW., Macuillamia obovata Raf., Macuillamia repens (SW.) Pennell

Taxonomy: available through www.itis.govITIS logo

Identification: According to Radford et al. (1968), Thieret (1970), Barrett and Strother (1978):

Habit: annual wetland emergent herb/forb, growing on wet soil or in shallow water

Stems/roots: prostrate to erect, pubescent to strigose, 1-4 dm long or tall, rooting in soil

Leaves: 10--23 mm, generally obovate to elliptic, entire palmately 5-13 veined

Flowers: short-pedicellate 0-25 mm, bractlets absent, glabrous to pubescent, solitary or paired in leaf axils. Sepals 4 (5), 3-4 mm long, corolla white or tinged with pink, campanulate, 3-4 mm long, lobes slightly shorter than the tube, stamens 4

Fruits/seeds: ellipsoid to oval fruits 2-3 mm long and ± 1.5 mm wide, tipped with persistent styles. Seeds are 0.4-0.5 mm long, 0.2 mm wide, cylindric to ellipsoid, brown yellow and reticulate

Look-a-likes: Other Bacopa species with white flowers include Bacopa monnieri (smooth water hyssop, native) which has obovate to oblanceolate 1-veined leaves and is entirely glabrous, Bacopa rotundifolia (disk waterhyssop, native) has orbicular glabrous leaves and Bacopa stricta (yerba de culebra, native to Puerto Rico) which has serrate oblanceolate leaves

Native Range: Widespread in United States, Mexico and the West Indies to Argentina (Christenhusz 2011, Sosa et al. 2018) and in southwest China (Flora of China 1998). Bacopa repens is considered native in most of the parishes in Louisiana and counties of Arkansas, California, Florida, South Carolina, Texas and Virginia (BONAP 2019).

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 Bacopa repens are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CA195320051Butte Creek
FL200520051Big Cypress Swamp
SC193519351Carolina Coastal-Sampit
TX199819981Lower Neches

Table last updated 6/13/2021

† Populations may not be currently present.


Habitat: paddy fields, wet meadows, shallow water and wet soils, around irrigation ditches and rice fields, growing with Ammannia auriculata (eared redstem), Heteranthera limosa (blue mudplantain) and Rotala ramosior (lowland rotala).

Reproduction and spread: reproduces by seed, flowering in July-August. Seeds can be dispersed by birds, agricultural machinery, water and by contamination of rice seed stocks (Barrett and Seaman 1980).

Means of Introduction: Introduced likely through contaminated rice seed stocks (Barrett and Seaman 1980).

Status: Adventive in: Arkansas, California, Florida, Louisiana, South Carolina, Texas and Virginia (BONAP 2019).

Impact of Introduction: Reported as a weed of rice agroecosystems in California and Louisiana (Barrett and Strother 1978, Barrett and Seaman 1980). Rice yields are negatively correlated with weed density and duration of weed competition, with rice production reduced by 74 percent in Arkansas, 48 percent in Texas and 34-35 percent in Louisiana and California (Smith et al. 1977).

Remarks: The taxonomy of Bacopa is poorly defined (Christenhusz 2011, Sosa 2018), and may undergo future revision.

References: (click for full references)

Barrett, S. C. H. and D. E. Seaman. 1980. The weed flora of Californian rice fields. Aquatic Botany 9:351-376

Barrett, S. C. H. and J. L. Strother. 1978. Taxonomy and Natural History of Bacopa (Scrophulariaceae) in California. Systematic Botany 3(4):408-419

Britton, N.L. and P. Wilson. 1923-1926. Botany of Porto Rico and the Virgin Islands. Scientific Survey of Porto Rico and the Virgin Islands. New York Academy of Sciences, New York.

Brown, L. E. and K. N. Gandhi. 1989. Notes on the flora of Texas with additions, range extensions and one correction. Phytologia 67(5):394-399

Christenhusz, M. J. M. 2011. Plantaginaceae. In: Davidse, G., Sousa Sánchez, M., Knapp, S. & Chiang Cabrera, F. (Eds.) Flora mesoamericana. vol. 5. Missouri Botanical Garden Press, St. Louis.

Flora of China Editorial Committee. 1998. Flora of China (Scrophulariaceae through Gesneriaceae). 18: 1–449. In C. Y. Wu, P. H. Raven & D. Y. Hong (eds.) Flora of China. Science Press & Missouri Botanical Garden Press, Beijing & St. Louis. available online http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=210000098. Accessed on 10/22/2019

Hatch, S.L., K.N. Gandhi, and L.E. Brown. 1990. Checklist of the vascular plants of Texas (MP-1655). Texas Agricultural Experiment Station, College Station.

Hickman, J.C., ed. 1993. The Jepson Manual of the Higher Plants of California. Univ. of California Press, Berkeley.

Jepson Flora Project. 2019. http://ucjeps.berkeley.edu/cgi-bin/get_cpn.pl?BARE. Accessed on October 15, 2019.

Kartesz, J.T., The Biota of North America Program (BONAP). 2015. Taxonomic Data Center. (http://www.bonap.net/tdc). Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2015. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press)]

Pennell, F.W. 1935. The Scropulariaceae of eastern temperate North America. Academy of Natural Sciences of Philadelphia Monographs 1: 1-650. Academy of Natural Sciences, Philadelphia.

Radford, A. E., H. E. Ahles and C. R. Bell. 1968. Manual of the vascular flora of the Carolinas. University of North Carolina Press, Chapel Hill.

SERNEC Data Portal. 2019. http//:sernecportal.org/portal/index.php. Accessed on October 15, 2019.

Smith, R. J., W. T. Flinchum and D. E. Seaman. 1977. Weed control in U.S. rice production. Agriculture Handbook No. 497, Agricultural Research Service, U.S. Dept. of Agriculture in cooperation with Arkansas, California, and Texas Agricultural Experiment Stations. Washington, D.C.

Sosa, M. D., P. Moroni and N. O'Leary. 2018. A taxonomic revision of the genus Bacopa (Gratioleae, Plantaginaceae) in Argentina. Phytotaxa 336(1):1-27

Thieret, J. W. 1970. Bacopa repens (Scrophulariaceae) in the Conterminous United States. Castanea 35(2):132-136

Thomas, R.D. and C.M. Allen. 1993-1998. Atlas of the Vascular Flora of Louisiana, Volumes 1-3. Louisiana Department of Wildlife and Fisheries. Natural Heritage Program.

Turner, B.L., H. Nichols, G. Denny, and O. Doron. 2003. Atlas of the Vascular Plants of Texas, Vols. 1 and 2. Botanical Research Institute of Texas, Fort Worth.

Ulloa Ulloa, C., P. Acevedo-Rodríguez, S. G. Beck, M. J. Belgrano, R. Bernal, P. E. Berry, L. Brako, M. Celis, G. Davidse, S. R. Gradstein, O. Hokche, B. León, S. León-Yánez, R. E. Magill, D. A. Neill, M. H. Nee, P. H. Raven, H. Stimmel, M. T. Strong, J. L. Villaseñor Ríos, J. L. Zarucchi, F. O. Zuloaga & P. M. Jørgensen. 2017. An integrated assessment of vascular plants species of the Americas. Science 358: 1614–1617, f. 1–4.

USDA, NRCS. 2019. The PLANTS Database (http://plants.usda.gov, 22 October 2019). National Plant Data Team, Greensboro, NC 27401-4901 USA.

Wunderlin, R.P., and B.F. Hansen. 2009. Atlas of Florida Vascular Plants (http://www.plantatlas.usf.edu/) [S.M. Landry and K.N. Campbell (appl. dev.), Florida Center for Community Design and Res.] Inst. for Systematic Botany, Univ. of S. Florida, Tampa.

Author: Anemaet, E.R.

Revision Date: 6/4/2021

Citation Information:
Anemaet, E.R., 2021, Bacopa repens (Sw.) Wettst.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=3069, Revision Date: 6/4/2021, Access Date: 6/16/2021

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. [2021]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [6/16/2021].

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