Common name: water snowflake

Synonyms and Other Names: floating-heart, Limnanthemum indicum (L.) Thwaites, Villarsia indica (L.) Vent.

Taxonomy: available through www.itis.gov

Identification: Nymphoides indica is a perennial with a long (up to 3 m) floating stem, rooted in the bottom soils and at stem nodes (Marwat et al. 2009; Sutton 1994). Leaf round to heart-shaped (10-30 cm wide), flat, bright green color. Leaf margins entire and wavy, veins indistinct and palmate. Several flowers can arise from a single plant, clustered, white with a yellow center (2.5-3.5 cm wide). Upper surface densely fringed and covered with frilly hairs (Marwat et al. 2009; Sutton 1994). Flowers last for only one day. Capsules elliptic (3-5mm) with few seeds. Seeds brown, spherical, smooth and less than 1.5mm wide. Leaves often found with associated plantlets.

The fringed petals of N. indica best distinguish it from non-native N. cristata and N. peltata and native N. aquatica and N. cordata, although two natives of South/Central America and the Caribbean, N. humboldtiana and N. grayana, both have fringed white and yellow petals, respectively (Tippery et al. 2011; Tippery et al. 2015). Thus, molecular techniques are typically needed to determine between N. indica and N. humboldtiana (Tippery et al. 2011). Nymphoides humboldtiana is currently known to grow in Florida, Puerto Rico, and Texas where it was misidentified as N. indica (Beth Middleton, pers. comm. 2018).

Size: Stem length up to 3 meters (Marwat et al. 2009)

Native Range: White-flowered populations were previously considered native to the Caribbean, including Puerto Rico, through much of Central and South America, and tropical Asia and Africa (Ornduff 1969; Ornduff and Mosquin 1970). However the Caribbean and Central/South American populations are likely N. humboldtiana (Tippery et al. 2011). The yellow-flowered populations were originally thought to be variants of N. indica, but were later confirmed to be a separate species, N. grayana, native to the Caribbean (Ornduff and Mosquin 1970; Tippery et al. 2015).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

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

Ecology: The genus Nymphoides contains approximately 50 species globally (Tippery and Les 2011), mostly found in tropical regions (Ornduff and Mosquin 1970).

Nymphoides spp. display a rare floral arrangement referred to as “dimorphic heterostyly”, a sexual condition characterized by the spacial separation of anthers and stigma occurring reciprocally in different plants. This promotes outcrossing since the pollen is located at a different height than the stigma, of the same flower, but corresponding to the height of receptive stigmas on compatible flowers of the opposite morph type (Tippery and Les 2011). The corolla ruffled fringe gives the flower additional buoyancy. While making up about 10% of the floral mass, it increases flower buoyancy by 50% (Armstrong 2002).  Flowers of Nymphoides are clearly adapted to pollinators (Ornduff and Mosquin 1970).

Nymphoides indica disperses vegetatively when leaves and associated adventitious roots become free-floating for a period of time, eventually sinking to the bottom and giving rise to new plants (Mason and van der Valk 1992; Willey and Langeland 2011). Single leaves can produce new plants (known as viviparity) (Elmqvist and Cox 1996; Mason and van der Valk 1992).

Means of Introduction: Species of the Nymphoides genus are commonly sold in the aquarium and water garden trade. Plants may be unintentionally introduced or intentionally planted as ornamental species in waters where they escape into the wild. Once introduced, plants can reproduce in several ways. Vegetative propagation from tubers, daughter plants, rhizomes and leaves (each leaf can produce a plantlet). Plants also reproduce sexually from seed. Plantlets, leaves, and fragments can drift when detached from the underwater stem and move to infest new locations (Willey and Langeland 2011; Sutton 1994). Plant seeds are likely spread from waterbody to waterbody attached to water birds and mammals.

Status: The populations in Florida are assumed established, while the status of the Hawaiian population is unknown.

Impact of Introduction: Nymphoides indica can form a dense, monotypic canopy on the water surface excluding other native plants (DiTomaso and Healey 2003). This condition can create a stagnant, low-oxygen condition in the water column below. The mat-like growth can impede water flow, trap floating debris, and impede recreational activities.

References: (click for full references)

Anderson, L.C. (curator). 2009. Herbarium Specimen Voucher Data, Florida State University (FSU), Herbarium. Florida State University, Tallahassee, FL. http://herbarium.bio.fsu.edu/.

Armstrong, J.E. 2002. Fringe science: are the corollas of Nymphoides (Menyanthaceae) flowers adapted for surface tension interactions? American Journal of Botany 89(2):362-365.

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.

DiTomaso, J.M. and E.A. Healey. 2003. Aquatic and riparian weeds of the West.  University of California, Agriculture and Natural Resources.  Oakland, California.

Elmqvist, T. and P.A. Cox. 1996. The evolution of vivipary in flowering plants. Oikos 77(1):3-9.

Marwat, S.K., M.A. Khan, M. Ahmad, and M. Zafar. 2009. Nyphoides indica (L.) Kuntze, a new record for Pakistan. Pakistan Journal of Botany 41(6):2657-2660.

Mason, D., and A.G. van der Valk. 1992. Growth responses of Nymphoides indica seedlings and vegetative propagules along water depth gradient. Aquatic Botany 42:339-350.

Ornduff, R. 1966. The origin of dioecism from heterostyly in Nymphoides (Menyanthaceae). Evolution 20(3):309-314.

Ornduff, R. 1969. Neotropical Nymphoides (Menyanthaceae): Meso-American and West Indian species. Brittonia 21(4):346-352.

Ornduff, R., and T. Mosquin. 1970. Variation in the spectral qualities of flowers in the Nymphoides indica complex (Menyanthaceae) and its possible adaptive significance. Canadian Journal of Botany 48:603-605.

Smithsonian Institution. 2014. National Museum of Natural History specimen collections. Accessed via GBIF data portal, http://www.gbif.org/dataset/5df38344-b821-49c2-8174-cf0f29f4df0d. Smithsonian Institution, Washington, DC. http://www.gbif.org/dataset/5df38344-b821-49c2-8174-cf0f29f4df0d. Created on 03/10/2014. Accessed on 05/19/2014.

Sutton, D.L. 1994. Culture of water snowflake. Pages 409-413 in Proceedings of the Florida State Horticultural Society. Lake Alfred, FL.

Tippery, N.P., and D.H. Les. 2011. Evidence for the hybrid origin of Nymphoides montana Aston (Menyanthaceae). Telopea 13(1-2):285-294.

Tippery, N.P., D.H. Les, and C.R. Williams. 2011. Nymphoides humboldtiana (Menyanthaceae) in Uvalde County, Texas - a new record for the U.S.A. Journal of the Botanical Research Institute of Texas 5(2):889-890.

Tippery, N.P., D.H. Les, and E.L. Peredo. 2015. Nymphoides grayana (Menyanthaceae) in Florida verified by DNA and morphological data. Journal of the Torrey Botanical Society 142(4):325-330.

Willey, L.N., and K.A. Langeland. 2011. Aquatic weeds: crested floating heart (Nymphoides cristata). Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL.

Other Resources:
Know Nymphoides (USGS)

Tippery Lab at University of Wisconsin-Whitewater

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

Peer Review Date: 3/23/2016

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.