Heteranthera reniformis - Ruiz & Pavon
Kidneyleaf Mud-plantain
Other Common Names: kidneyleaf mudplantain
Taxonomic Status: Accepted
Related ITIS Name(s): Heteranthera reniformis Ruiz & Pavón (TSN 42616)
Unique Identifier: ELEMENT_GLOBAL.2.159612
Element Code: PMPON03040
Informal Taxonomy: Plants, Vascular - Flowering Plants - Other flowering plants
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Liliales Pontederiaceae Heteranthera
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Heteranthera reniformis
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 28Mar1994
Global Status Last Changed: 16May1984
Rounded Global Status: G5 - Secure
Reasons: Populations of this species spread in a weedy fashion in preferred habitat. Its range is large, from Paraguay and Argentina to New York State; it is very common in wetlands in Central America. On the periphery of its range, it is considered rare because of several factors: (1) it requires a habitat that is restricted; (2) populations fluctuate dramatically due to succession and competition and water levels; and (3) it is difficult to monitor due to the above factors. It has become weedy in southern Europe, perhaps introduced from Brazil.
Nation: United States
National Status: N4N5

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (SNR), Arkansas (SNR), Connecticut (SH), Delaware (S4), District of Columbia (SNR), Florida (SNR), Georgia (S3?), Illinois (S1), Indiana (SNR), Iowa (S1), Kentucky (S4?), Louisiana (SNR), Maryland (SNR), Mississippi (SNR), Missouri (SU), New Jersey (S4S5), New York (S3), North Carolina (S2?), Ohio (S1), Pennsylvania (SNR), South Carolina (S1), Tennessee (SNR), Texas (SNR), Virginia (S4), West Virginia (S1)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Heteranthera reniformis is principally a species of the American tropics. It ranges from a sinkhole area in Illinois at its northwestern edge; east to New York, Delaware and Connecticut; south along the coast and to Texas where it is known from only one collection; to Mexico and Central America where it is common; and the West Indies (e.g., Puerto Rico, Jamaica), south to Paraguay and Argentina. In the United States, it is most common near the Mississippi River in Louisiana and western Tennessee. In Kansas, Nebraska and Oklahoma, any records for H. reniformis are most likely H. multiflora (i.e., were misidentified). There are no positively identified H. reniformis specimens in these three states (Horn 1994) nor does the species exist in Indiana (Hellmich 1994). A distribution map can be found in Horn (1985).

H. reniformis, along with H. limosa, another American subtropical species, is also found in northern Italy on the borders of rice fields (70-100 meters). Populations have been found on the Plain of Lombardy in the Pavia area and to the south of Milan. It was observed for the first time in 1968 near Pavia in the village of Marcignago and Vidigulfo. Since then it has been observed in different areas of the Plain of Lombardy, and now it looks as if the range is expanding (Pignatti 1982). H. limosa has also been noted, with some possible uncertainty in identification, in Carmague, south France. It seems that only an examination of herbarium specimens could conclude that is not H. reniformis (Lagarde and Gauthier 1991).

Number of Occurrences: 81 to >300
Number of Occurrences Comments: There are approximately 200 collection sites listed in herbarium records for Heteranthera reniformis. There are certainly many more undocumented sites as a result of limited collecting, especially in the tropics. The ephemeral nature of the plant and fluctuating populations may also limit collection. Documented extant occurrences in: New York (22), West Virginia (5), Ohio (1), Illinois (2). Also reported in Alabama (1), Arkansas (six counties), Georgia (5), Iowa (one county), North Carolina (two, maybe twelve, counties), South Carolina (3).

Population Size Comments: There are numerous populations across the range, especially in Central America, with thousands of individuals. Population numbers fluctuate (often widely) from year to year.

Overall Threat Impact Comments: In general, this species is not threatened globally. Potential threats to individual populations of this species include permanent alteration of the hydrology of the habitat (e.g., draining wetlands for agriculture, damming of rivers) and radically altering areas where seedbanks and populations exist (e.g., bulldozing, riverbank stabilization). In West Virginia, one population is subject to fluctuating water levels due to an upstream dam (WV NHP 1992). Perhaps the most common threat to H. reniformis is shading and competition from other wetland plants, particularly some sedges and grasses. For example, in Ohio the most pertinent threat for one population is being crowded out by Phalaris sp. (Cusick 1992). The species will colonize an area when conditions are favorable, but then easily disappear with succession. It could be threatened by invasive exotics such as purple loosestrife. Another threat is disturbance related to trampling and erosion caused by fishing along the banks of rivers (Cusick 1992). A similar species, Heteranthera limosa (ducksalad, an annual broadleaf weed in rice), is greatly affected by infestations of the waterlily aphid, Rhopalosiphum nymphaeae. In 1985 and 1986 field experiments showed that aphids reduced total biomass by 58% and 87% respectively (Oraze and Grigarick 1992). It is unknown whether this or related aphid species would have the same effect on H. reniformis.

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: There are no indications that Heteranthera reniformis is declining in range or abundance; it remains common through most of its range. The distribution, in fact, seems to be expanding (at least as an exotic)! Specimens collected from a rice field in Italy appear to be most similar to H. reniformis in Brazil. Recent reports state that the distribution in Italy is increasing (Horn 1994).

Intrinsic Vulnerability Comments: Populations decline in unfavorable water depths and are easily shaded out by competing vegetation. However, the species is able to recolonize habitat quickly.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Heteranthera reniformis is principally a species of the American tropics. It ranges from a sinkhole area in Illinois at its northwestern edge; east to New York, Delaware and Connecticut; south along the coast and to Texas where it is known from only one collection; to Mexico and Central America where it is common; and the West Indies (e.g., Puerto Rico, Jamaica), south to Paraguay and Argentina. In the United States, it is most common near the Mississippi River in Louisiana and western Tennessee. In Kansas, Nebraska and Oklahoma, any records for H. reniformis are most likely H. multiflora (i.e., were misidentified). There are no positively identified H. reniformis specimens in these three states (Horn 1994) nor does the species exist in Indiana (Hellmich 1994). A distribution map can be found in Horn (1985).

H. reniformis, along with H. limosa, another American subtropical species, is also found in northern Italy on the borders of rice fields (70-100 meters). Populations have been found on the Plain of Lombardy in the Pavia area and to the south of Milan. It was observed for the first time in 1968 near Pavia in the village of Marcignago and Vidigulfo. Since then it has been observed in different areas of the Plain of Lombardy, and now it looks as if the range is expanding (Pignatti 1982). H. limosa has also been noted, with some possible uncertainty in identification, in Carmague, south France. It seems that only an examination of herbarium specimens could conclude that is not H. reniformis (Lagarde and Gauthier 1991).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States AL, AR, CT, DC, DE, FL, GA, IA, IL, IN, KY, LA, MD, MO, MS, NC, NJ, NY, OH, PA, SC, TN, TX, VA, WV

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CT Fairfield (09001)*, New Haven (09009)*
IA Lucas (19117)*
IL Alexander (17003), Pope (17151)*, Pulaski (17153)*, Union (17181)*
OH Lawrence (39087), Meigs (39105)
SC Calhoun (45017), Laurens (45059), Newberry (45071)
WV Fayette (54019), Jackson (54035)*, Mason (54053), Morgan (54065), Wirt (54105)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Housatonic (01100005)+*
02 Cacapon-Town (02070003)+
03 Saluda (03050109)+, Lake Marion (03050111)+
05 Upper Ohio-Shade (05030202)+, Little Kanawha (05030203)+*, Lower New (05050004)+, Gauley (05050005)+*, Upper Kanawha (05050006)+*, Raccoon-Symmes (05090101)+, Lower Ohio-Bay (05140203)+*
07 Lake Red Rock (07100008)+*, Upper Mississippi-Cape Girardeau (07140105)+*, Cache (07140108)+
10 Upper Chariton (10280201)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: Herbaceous annual with floating or immersed round, reniform leaves on long petioles; flowers white or pale blue with 2 ovate, yellow posterior anthers and a third larger greenish anther.
General Description: This mud-plantain grows from an underwater cluster of basal leaves and sends up a prostrate floating stem with kidney-shaped, dark green, shiny, leaves and an emergent spike. The flower cluster is elongate, 1-9 cm long, surrounded by a specialized folded leaf (spathe), 8-55 mm long, 2-5 mm wide, and contains 2-8 flowers. Flowers all open on the same day, are white, densely hairy, and have 6 petals (Horn 1985).
Technical Description: Horn (1985) described Heteranthera reniformis as follows: "Vegetative stem submersed with elongate nodes or emersed and procumbent; flowering stem glabrous, 1-9 cm long, the upper internode 0.5-4 cm. Sessile leaves submersed, forming a basal rosette, thin, whitened on abaxial surface, linear to oblanceolate, acuminate at apex; petiolate leaves floating or emersed, reniform, obtuse to acute at apex; 1-4 cm long, 1-5 cm wide, the length equal to or less than the width, the petiole glabrous, 2-13 cm long. Stipules 1-5 cm long. Inflorescence a spike with 2-8 flowers, all opening the same day; peduncle glabrous, 5-42 mm long; spathe folded, 8-55 mm long, 2-5 mm wide. Flowers with perianth white, densely glandular pubescent on outside, the tube 5-10 mm long, the wings linear, acuminate at apex, 3.0-6.5 mm long, 5 above and 1 below, the central upper wing with yellow or green region at the base, sometimes with a brown spot above; lateral stamens yellow, 0.9-2.2 mm long, the filaments linear, pubescent with white multicellular hairs toward the apex, the anthers rounded, 0.2-0.8 mm long; central stamen yellow or blue, 2.2-4.7 mm long, the filament linear, sparsely pubescent with multicellular hairs, the anther oblong, 0.8-1.8 mm long; style white, pubescent with multicellular hairs. Seeds many, 0.5-0.9 mm long, 0.3-0.5 mm wide, with 8-14 longitudinal wings."
Diagnostic Characteristics: Heteranthera reniformis and H. multiflora are very similar in gross morphology. H. reniformis can be distinguished by the following characteristics: the internode of the flowering stem is generally longer (0.5-5 cm vs. less than 1 cm in H. multiflora); the spike is generally shorter than the spathe; inflorescences have fewer flowers (2-8 vs. 3-16); lateral filament hairs are multicellular, and white rather than purple; the perianth is white, rarely blue, and densely glandular pubescent on the outside rather than pale purple or white and scarcely glandular pubescent; and the sessile leaves of seedlings are in a basal rosette rather than on an elongate stem. The species have differing chromosome numbers: H. reniformis (2n = 48) and H. multiflora (2n = 32) (Horn 1994, Rosatti 1987). The ranges of Heteranthera reniformis and H. multiflora overlap in the United States; however, H. multiflora is more typical of the central and eastern plain states (Snyder 1988), whereas H. reniformis ranges from the eastern plain states to the east coast. In addition, H. multiflora is more likely to inhabit deeper water because of its superior ability to produce elongate stems (Horn 1985, Rosatti 1987).

H. reniformis is also easily confused with H. peduncularis, a species occurring primarily in the Mexican highlands (Snyder 1988). Those in western Missouri are assigned to H. peduncularis by Gleason (1952); however, Steyermark (1963) argues that the criteria for this assignment (i.e., with H. reniformis, the spathe and leaf next below it are separated by a conspicuous internode and the base of the short spike is included by the spathe, whereas with H. peduncularis the spathe and leaf next below it are contiguous and the base of the spike is exserted from the spathe) are only based upon a growth phase and would therefore assign these to H. reniformis. In addition, the leaves of H. peduncularis are cordate-rotund, the spathe is loosely sheathing at the base and is abruptly caudate-acuminate (Gleason 1952), the inflorescence is more elongate, and the filaments are glabrous or nearly so (Horn 1985).

In H. rotundifolia, the leaves are more round and the lobes, on the single flower, are not as acute as in H. reniformis, which has 2-8 flowers (Horn 1987a).

Ecology Comments: Heteranthera reniformis is a fugitive species of wetlands. Although H. reniformis can grow rapidly to form dense mats when competition is low, it is a poor competitor with sedges and rushes. It will grow well for a few years on the edges of ponds and marshes before it is shaded out (Horn 1994).

Phenology: Heteranthera reniformis is an annual even in the tropics (Horn 1994). The seedling is a rosette of leaves that grows in rich soil in shallow water. The rest of the plant reaches the surface where the procumbent stems can grow on mud or float on the water surface.

Blooming in North America mainly starts in July, but the plant can flower from late May to September and can continue until frost. In New York at the northern limit of its range, the plant is vegetative through June and July, flowers in August, and fruits in September (Young 1992). South of the equator in Paraguay, the species is in flower and fruit from August to May (Horn 1987b). The flowers are very ephemeral in nature; all flowers on an inflorescence will open in the morning and close by the afternoon of the same day. Flowers on submerged inflorescences will not open (Horn 1985, Horn 1994, Yatskievych 1994).

Germination: Seedbanks may exist in the soil for many years (Horn 1994). Conditions optimum for seed germination may include daily fluctuations in temperature. These fluctuations naturally raise and lower soluble oxygen levels and may act as a trigger for germination (Horn 1994).

Pollination: The flowers lack nectaries. Pollen collecting bees visit the conspicuous yellow anthers of the shorter stamens and pick up pollen from the pale blue or greenish anther of the long central stamen (Rosatti 1987 quoting from another publication: Lovell, The Flower and the Bee). The cleistogamously fertilized ovules develop into normal-sized fruits (Horn 1985).

Habitat Comments: Heteranthera reniformis prefers open sunny areas with nutrient-rich soil and water no more than 15 cm deep (Horn 1994). Because it is a poor competitor with many sedges, rushes and other wetland species, H. reniformis is easily crowded out of wetlands. It is, however, able to take advantage of positive growing situations immediately, such as newly flooded areas (from excessive rain, beaver dams, or human activity) and areas where competition is removed (as in the case of herbicide use). As a result, this species is found in seemingly disjunct and dissimilar areas such as ponds and sinkholes, rice fields, ditches, and power-line corridors. Soil seedbanks are thought to exist for many years; as a result, populations show up unexpectedly when conditions improve. This could explain populations that appear unexpectedly when rice fields are flooded. Historically, Heteranthera reniformis may have benefited from the hydrologic changes created by beavers (Horn 1994).

A summary of habitat types by state and country follows:

In Connecticut, H. reniformis has been found along creek banks and in a freshwater tidal zone growing on mud in midtide range (CT NDD 1994).

Georgia populations can be found in fairly disturbed habitats where it can be abundant and show up erratically (Allison 1994).

In Iowa, H. reniformis was noted from a historic collection in Red Haw State Park growing in 2-3 inches of water (IA NAI 1994).

In Missouri this species occurs "along sloughs, ditches of valleys and swampy depressions and margins of artificial and natural ponds, especially of oxbow lakes in river bottoms" (Steyermark 1963).

In Camden County, New Jersey, Heteranthera reniformis generally occurs in less densely vegetated zones of marshes than H. multiflora which occurs with Typha spp.; H. reniformis occurs with Nuphar lutea, Sagittaria graminea, S. subulata, Eleocharis parvula and Ludwigia palustris (Snyder 1988).

In New York, Heteranthera reniformis is often vigorous and common on open mudflats (including both sandy and silty tidal mud substrates) and marshes, particularly in areas with little competition from other plants. Associates include Sagittaria subulata, Scirpus spp. and Nuphar sp. It commonly occurs as an understory to peltate-leaved emergent and sometimes in "grassy" areas. Populations have also been noted to be most dense and robust near manure dumps and boundaries between marshes and cow pastures. It was also noted to be mat-forming in a freshwater intertidal marsh where it is isolated from other plants along the mudflat (NY NHP 1994).

In North Carolina, this plant is found creeping in mud or floating in shallow water (Radford et al. 1968).

In Ohio, two extant populations occur in the Ohio River, one of which is on a narrow linear strip of mud bar along the Ohio River edge where it is flooded in high water and locally abundant. An adjacent population across the river in West Virginia should perhaps be called the same population (Cusick 1992). The other population is several miles downstream in a muddy area that is highly disturbed because of trampling and erosion caused by fishing along the riverbanks. In both areas, the water levels remain fairly stable due to dams on the river (Cusick 1994).

In South Carolina, the one element occurrence record is from a stream in shallow water (SC HT 1994).

In Virginia, it is noted to occur in swampy and inundated woods (Fernald 1935).

In West Virginia, reported habitats include: a creek under willows, a shallow pool in a river gorge, and muddy riverbanks and shorelines with Ludwigia peploides and L. leptocarpa. (

In Northern Italy, Heteranthera occurs in a rice field where it is becoming quite weedy.)

A 1940 Cuban record is from a water-filled depression in a cane field road (University of Minnesota Herbarium [MIN]).

H. reniformis has been collected in Ecuador from marshy ground and a small pond (Horn 1987a).

In Guatemala, H. reniformis is generally found in mud, along ponds or lakes, or along streams or ditches at 2000 meters or lower. Plants are usually creeping on mud and rarely floating.

In Honduras, collections dated 1948 were made from a marsh along the Rio Charrera and a roadside ditch near the Rio Yeguare (University of Minnesota Herbarium [MIN]).

The species occurs in Mexico (Horn 1985, Urbina 1897). One collection from 1926 was made from swamps and pools in Jalisco (University of Minnesota Herbarium [MIN]).

In Jamaica, it is locally common in ditches, swamps and sluggish streams (Adams 1972).

In Panama, the following habitats are mentioned: swamps in pasture, bogs, and a pool in a savanna (Woodson and Schery 1944). In Paraguay the species is found in "suelo humedo y aguas poco profundas" (moist soil and shallow waters) (Horn 1987b).

Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Management for preservation of Heteranthera reniformis is not a significant issue. H. reniformis is not a rare species, although dramatic populations fluctuations and its mucky habitat make it difficult to track. It is also a species that seems to require little more than rich soil, shallow water, and open sunny places with negligible competition. This mud plantain is found in natural wetlands and rivers as well as in rice field, ditches, and powerline corridors. When environmental conditions are favorable, populations may appear from unknown seedbanks or spread from only a few individual plants to dense mats of vegetation in short periods of time. Populations will disappear just as quickly when environmental conditions are not favorable. Populations will come and go quickly from an area depending on several important environmental factors: it cannot propagate in water much deeper than 15 cm, as the maturing plant will be unable to reach the water surface; it cannot withstand too much shade or competition from other wetland plants. If management and monitoring is a concern, as it may be on the edge of its range, one must keep in mind the above needs.
Species Impacts: Currently it is unknown whether H. reniformis would have an impact on other rarer species in areas where it grows profusely. Although it has the potential to be weedy, it is easily crowded out by competing vegetation and generally grows in areas where other vegetation is not established.
Restoration Potential: If restoration is desirable (e.g., on the edge of its range), the potential is good if water depth is less than 15 cm and there is little competing vegetation. Propagation is relatively easy (Horn 1994).
Preserve Selection & Design Considerations: In these situations, efforts could be made to: (1) protect the biodiversity of its wetland habitats, and (2) maintain related hydrology of the wetland system so that the populations retain appropriate water depths from year to year. It may be preferable that water levels fluctuate somewhat from year to year; however, periods of drought or inundations that last longer than the seedbank viability could eliminate the population.
Management Requirements: Heteranthera reniformis favors open areas with shallow water, rich soil, and little competing vegetation. These simple requirements are met in ditches, power line corridors, rice fields, pond edges, and marshy areas.

Water levels may be allowed to fluctuate; however, the ideal depth (less than 15 cm) allows the plant to send vegetative shoots to the surface. It is speculated that historically this plant has benefitted from beaver activity that caused water levels vary tremendously. The plant also relies on its superior seedbank capabilities to regenerate populations (Horn 1994). Competition from other wetland species will cause populations to die back rapidly; therefore, in some cases, fluctuating water levels may be helpful in maintaining an advantageous vegetative structure (Cusick 1994).

It has been demonstrated that H. reniformis does well following herbicide application to the habitat, presumably because competing species are removed (Horn 1994). Because this destroys biodiversity, it is not a recommended management tool.

Monitoring Requirements: Annual counts are perhaps most important when monitoring this species to record the dramatic population changes that are likely to occur. Monitoring should focus on areas where populations currently exist as well as places that are historic and potential sites. Searches made during wet periods could reveal "new" populations that are likely to sprout from soil seedbanks in wet depressions (Horn 1994).

Management Programs: There are no known management programs, likely because the species is not globally rare and because populations occur in artificial habitats such as rice fields.
Management Research Programs: There is speculation that the seeds of several Heteranthera species could survive in the soil for many years. Horn (1994) is researching this aspect with H. limosa. There are no management research programs known to exist for H. reniformis at this time.
Management Research Needs: A better understanding of the species' seedbank longevity and the causes and effects of population fluctuations would be helpful in determining how much and what kind of management is needed for protection on the edge of its range.
Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 18May1995
NatureServe Conservation Status Factors Author: Hengelfelt, J., 1995; S.L. Neid, 1998.
Management Information Edition Date: 11May1993
Management Information Edition Author: MIKE PENSKAR, MIHP; HENGELFELT, JENNIFER (1994)
Element Ecology & Life History Edition Date: 04May1994
Element Ecology & Life History Author(s): HENGELFELT, JENNIFER (1994)

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Barrett. S. C. H. 1978. Pontederiaceae. In Heywood, V. H. (editor), Flowering plants of the world, New York. Pp. 309-311.

  • Bowles, M.L., et al. 1991. Rarely seen endangered plants, rediscoveries, and species new to Illinois. Erigenia 11:27-51.

  • Correll, D.S. and M.C. Johnston. 1970. Manual of the Vascular Plants of Texas. Texas Research Foundation, Renner, TX.

  • Cusick, A.W. 1988. Noteworthy collections. Castanea 53: 311-314.

  • Deam, C. C. 1940. Flora of Indiana. Division of Forestry, Dept. of Conservation, Indianapolis, Indiana. 1236 pp.

  • Fernald, M. L. 1935. Midsummer vascular plants of Virginia. Rhodora November 1935: 407.

  • Fernald, M. L. 1950. Gray's Manual of Botany, 8th edition. American Book Company, New York.

  • Gleason, H.A. 1952. The new Britton and Brown illustrated flora of the northeastern United States and adjacent Canada. 3 volumes. Hafner Press, New York. 1732 pp.

  • Godfrey, R.K., and J.W. Wooten. 1979. Aquatic and wetland plants of southeastern United States: Monocotyledons. Univ. Georgia Press, Athens. 712 pp.

  • Harvill, A.M, Jr. C.E.Stevens, and D.M.E.Ware. 1977. Atlas of the Virginia Flora, Part 1: Pteridophytes through Monocotyledons. Virginia Botanical Associates. Farmville, VA.

  • Hellquist, C.B. and G.E. Crow 1982. Aquatic vascular plants of New England: part 5. Araceae, Lemnaceae, Xyridaceae, Eriocaulaceae, and Pontederiaceae. New Hampshire Agricultural Experiment Station, University of New Hampshire. Station Bull. 523.

  • Horn, C.N. 1985. A systematic revision of the genus Heteranthera (sensu lato: Pontederiaceae). Doctoral dissertation, Department of Biology, University of Alabama.

  • Horn, C.N. 1987a. Pontedericaeae. In: Flora of Ecuador, Harling, G. and L. Anderson, eds., Nordic Journal of Botany, No. 29. 20pp.

  • Horn, C.N. 1987b. Pontederiaceae. In: Flora del Paraguay, R. Spichiger, ed. Conservatoire et Jardin botaniques de la Violle de Geneve and the Missouri Botanical Garden. 28pp.

  • House, Homer D. 1924. Annotated list of the ferns and flowering plants of New York State. New York State Museum Bulletin 254:1-758.

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  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1996. Species distribution data at state and province level for vascular plant taxa of the United States, Canada, and Greenland (accepted records), from unpublished data files at the North Carolina Botanical Garden, December, 1996.

  • Lagarde, F. et M. Gauthier. 1991. Heteranthera limosa (Sw.) Willd. (Pontederiaceae) en France. Bull. Soc. Bot. Fr. 138, Lettres bot. (3) 239-240.

  • Lelong, M.G. 1988. Noteworthy monocots of Mobile and Baldwin counties, Alabama. SIDA 13: 101-113.

  • Mohlenbrock, R.H. and J.W. Voigt. 1965. An annotated checklist of vascular plants of the Southern Illinois University Pine Hills field station and environs. Trans. Ill. State Acad. Sci. 58:268-301.

  • Ogden, E.C. 1974. Anatomical patterns of some aquatic vascular plants of New York. New York State Museum Bull. 424.

  • Oraze, M. J. and A. A. Grigarick. 1992. Biological control of ducksalad (Heteranthera limosa) by the waterlily aphid (Rhopalosiphum nymphaeae) in rice (Oryza sativa). Weed Science 40: 333-336.

  • Pignatti, S. 1982. Flora D'Italia, Vol. 3. Edagricole, Bologna.

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  • Radford, A.E., H.E. Ahles, and C.R. Bell. 1968. Manual of the vascular flora of the Carolinas. Univ. North Carolina Press, Chapel Hill, NC. 1183 pp.

  • Rhoads, A.F., and W. Klein. 1993. Atlas of the Flora of Pennsylvania: An Annotated Checklist. American Philosophical Society, Philadelphia, PA.

  • Roberts, M.L., and R.L. Stuckey. 1992. Distribution patterns of selected aquatic and wetland vascular plants in relation to the Ohio canal system. Bartonia 57:50-74.

  • Rosatti, T.J. 1987. The genera of Pontederiaceae in the southeastern United States. J. Arnold Arboretum 68: 35-71.

  • Seymour, F.C. 1982. The flora of New England. A manual for the identification of all vascular plants including ferns and fern allies growing without cultivation in New England. Moldenka, Plainfield, New Jersey.

  • Smith, E. B. 1988b. An atlas and annotated list of the vascular plants of Arkansas, 2nd edition. University of Arkansas, Fayetteville.

  • Snyder, D. B. 1988. Heteranthera multiflora in New Jersey: A first look. Bartonia 54: 21-23.

  • Taylor, Norman. 1915. Flora of the vicinity of New York. Memoirs of the New York Botanical Garden vol. V. New York, NY.

  • Urbina, M. 1897. Catalogo de plantas Mexicanas. Mexico (City) Museo Nacional.

  • Woodson, R.E., Jr. and R.W. Schery. 1944. Pontederiaceae. In: Flora of Panama, Annals of the Missouri Botanical Garden 31: 151-157.

  • Wunderlin, R.P. 1998. Guide to the Vascular Plants of Florida. University Press of Florida: Gainesville, Florida. 806 pp.

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