Potamogeton hillii - Morong
Hill's Pondweed
Other Common Names: Hill's pondweed
Taxonomic Status: Accepted
Related ITIS Name(s): Potamogeton hillii Morong (TSN 39034)
French Common Names: potamot de Hill
Unique Identifier: ELEMENT_GLOBAL.2.129028
Element Code: PMPOT030F0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Pondweed Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Najadales Potamogetonaceae Potamogeton
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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: Potamogeton hillii
Conservation Status
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NatureServe Status

Global Status: G3
Global Status Last Reviewed: 31Jul2015
Global Status Last Changed: 15Oct1986
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G3 - Vulnerable
Reasons: Relatively uncommon throughout a somewhat-limited range.
Nation: United States
National Status: N3
Nation: Canada
National Status: N2N3 (08Sep2016)

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 Connecticut (S1), Massachusetts (S3), Michigan (S2), New York (S2), Ohio (S1), Pennsylvania (S1), Vermont (S3), Virginia (S1), Wisconsin (S1)
Canada Ontario (S2S3)

Other Statuses

Canadian Species at Risk Act (SARA) Schedule 1/Annexe 1 Status: SC (15Aug2006)
Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Special Concern (05May2005)
Comments on COSEWIC: Reason for designation: An inconspicuous, rooted, aquatic plant currently known from fewer than 20 Canadian populations and occupying a very small total area of habitat. No imminent limiting factors have been identified that would have significant impacts on this globally rare species, but invasive exotic plants may be impacting some populations.

Status history: Designated Special Concern in April 1986. Status re-examined and confirmed in May 2005.

NatureServe Global Conservation Status Factors

Range Extent Comments: Potamogeton hillii occurs in Vermont, Massachusetts, Connecticut, New York, Pennsylvania, Ohio, Michigan, Wisconsin, and Ontario.

Number of Occurrences: 21 to >300
Number of Occurrences Comments: There are approximately 87 documented occurrences (post-1970 occurrences with specific locational information): Connecticut (1), Massachusetts (22), Vermont (27), New York (10), Pennsylvania (3), Ohio (4), Michigan (8), and Ontario (12). Likely over 100 occurrences are scattered across the range.

Population Size Comments: Several populations in Massachusetts and Vermont are extensive -- with thousands of plants reported.

Overall Threat Impact Comments:

Pollution and dredging appear to be the primary threats to this species over much of its range (Haynes 1974). Potamogeton hillii may rely on maintenance of high water quality, cool water temperatures and a natural habitat, although it has been known to persist in the vicinity of developments (Crispin and Penskar 1990).

According to Bissell (pers. comm.), increased turbidity in glacial lakes has had a significant negative impact on the diversity of aquatic flora in Ohio. Development of lake shorelines accompanied with septic tank discharge and agricultural field and lakeshore runoff, has led to the plummeting of aquatic plant species diversity in recent years. Bissell (pers. comm.) stated that the glacial lake aquatic community may be the most threatened plant community in the state.

Draining of wetlands for agricultural, residential and other types of development also appears to be a major threat (Nepstad 1981). Such was the fate of the type population of the species in Michigan (Voss 1965). Excessive pumping for irrigation or other uses has been known to destroy aquatic plant populations at some sites (Bissell pers. comm.).

Nepstad (1981) suggested that poor seed production, seed dispersal or establishment abilities may be the primary reason for this species rarity. Hellquist (1984), however, stated that the species produces large amounts of seeds, as well as winter buds, and has suggested that the species reproduces adequately. It is more likely that seed dispersal to proper habitats is the critical reason for its apparent rarity.

Nepstad (1981) also suggested that critically low population numbers may be the primary threat to the survival of P. hillii in Michigan. Currently, there is no sound population biology data concerning this issue.

Short-term Trend Comments: Trends in the number of individuals and occurrences are not known, but likely show a decline due to reduction in water quality since settlement.

Intrinsic Vulnerability Comments: Fairly susceptible to changes in habitat quality.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Potamogeton hillii occurs in Vermont, Massachusetts, Connecticut, New York, Pennsylvania, Ohio, Michigan, Wisconsin, and Ontario.

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 CT, MA, MI, NY, OH, PA, VA, VT, WI
Canada ON

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CT Litchfield (09005)
MA Berkshire (25003)
MI Charlevoix (26029), Cheboygan (26031), Emmet (26047), Kalkaska (26079), Mackinac (26097), Missaukee (26113)*, Otsego (26137), Presque Isle (26141)
NY Columbia (36021), Dutchess (36027), Essex (36031), Jefferson (36045), Lewis (36049), St. Lawrence (36089), Tompkins (36109)*, Warren (36113), Washington (36115)
OH Ashtabula (39007), Geauga (39055)
PA Bedford (42009), Crawford (42039)*, Erie (42049), Fulton (42057), Lancaster (42071)*, Mifflin (42087)*, Warren (42123)
VA Bath (51017)
VT Bennington (50003), Chittenden (50007), Franklin (50011), Rutland (50021), Washington (50023), Windham (50025), Windsor (50027)
WI Florence (55037)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Black-Ottauquechee (01080106)+, West (01080107)+, Middle Connecticut (01080201)+, Housatonic (01100005)+
02 Upper Hudson (02020001)+, Hudson-Hoosic (02020003)+, Middle Hudson (02020006)+, Raystown (02050303)+, Lower Juniata (02050304)+*, Lower Susquehanna (02050306)+*, Conococheague-Opequon (02070004)+, Upper James (02080201)+
04 Brule (04030106)+, Muskegon (04060102)+*, Manistee (04060103)+, Boardman-Charlevoix (04060105)+, Brevoort-Millecoquins (04060107)+, Lone Lake-Ocqueoc (04070003)+, Cheboygan (04070004)+, Black (04070005)+, Cuyahoga (04110002)+, Salmon-Sandy (04140102)+, Seneca (04140201)+*, Black (04150101)+, Oswegatchie (04150302)+, Indian (04150303)+, Raquette (04150305)+, Mettawee River (04150401)+, Otter Creek (04150402)+, Winooski River (04150403)+, Lamoille River (04150405)+, Missiquoi River (04150407)+, Lake Champlain (04150408)+
05 Upper Allegheny (05010001)+, French (05010004)+, Shenango (05030102)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A fully-submersed aquatic plant with very narrow leaves and stems up to 1 m.
Technical Description: Stem: green to olive, slightly compressed, heavily rigid, 30-60 cm long, 0.5-1.0 mm in diameter. Leaves pale-green to olive-green, delicate 3 nerved, 2.0-6.0 cm long, 0.6-2.5 (-4.0) mm wide; apex apiculate to bristle tipped: glands present or absent, brown to green, 0.1-0.3 mm diam. lacunae of 1-2 rows each side of midrib; lateral nerves joining midrib (0.4-) 0.7-1.7 mm from apex. Stipules white to light brown, slightly fibrous, rarely shredding at the tip, convolute, 7.0-16.0 mm long, 0.6-2.2 mm diam. Winter buds rare, terminal 2.8-3.0 cm long, 1.5-3.0 mm wide; inner leaves undifferentiated; outer leaves 3-4 per side, acute to apiculate, without corrugations at the base. Peduncles slightly clavate, axillary or terminal, rarely recurved, 6.0-13.5 mm long, 0.3-1.0 mm diam. Spike globose, (2.0-) 4.0-7.0 mm long, 4.6-7.0 mm diam; verticels 1-2, when 2 these crowded, 0.5-1.0 mm apart. Perianth segments 1.3-1.5 mm long, 1.1-1.5 mm wide. Fruit brown to light greenish-brown, dorsally and laterally keeled, 2.3-4.0 mm long, 2.0-3.2 mm wide; keels forming ridges, without undulations, to 0.2 mm high; beak central, rarely forward, 0.3-0.7 mm long, 0.2-0.6 mm diam; sides rounded rarely centrally depressed; wall texture rough. (Haynes 1974).
Diagnostic Characteristics: Rhizomes undeveloped, stem terete or nearly so, submersed leaves less than 4 mm wide, spikes with 1-5 verticels of flowers; fruit rounded on the sides and with 3 low, ridge like keels.
Duration: PERENNIAL
Reproduction Comments: n=13. Produces numerous winter buds and fruit.
Ecology Comments:

According to Hellquist (1984), Hill's pondweed is locally abundant at most of its locations. Apparently, the numerous winter buds and fruits produced by the plant enhance survival and facilitate spread to new sites (Hellquist 1984). Over-wintering buds as a means of vegetative reproduction, are produced in the fall and germinate in the spring (Crispin and Penskar 1990).

Plants are presumably water-pollinated (Haynes 1974). Mature fruits are formed in late July and August in Michigan (Crispin and Penskar 1990). Potamogeton hillii fruits are a favorite food of waterfowl which probably act as the major dispersal agents for this species of pondweed (Haynes 1974), although wind currents may serve to disperse seeds within a given aquatic system (Brownell 1986). The seeds of P. hillii are buoyant and facilitate dispersal by waterfowl through adhesion and by wind currents in water (Brownell 1986) and ingestion (Haynes 1974). In the digestion process, the mesocarp and exocarp are digested, but the endocarp protecting the inner viable seed is left intact.

When abundant, P. hillii may vastly increase the amount of surface area available to aquatic organisms (Brownell 1986). The species provides cover for amphibians, fish and other small organisms such as insects and snails. Potamogeton species have long been known as a food source for waterfowl, muskrats and other vegetarian animals (Martin and Uhler 1939), but no specific records apparently exist for P. hillii (Brownell 1986).

Riverine Habitat(s): Low gradient, SPRING/SPRING BROOK
Lacustrine Habitat(s): Shallow water
Habitat Comments:

Potamogeton hillii is known from western New England and New York to southern Ontario and northern Michigan, south to Pennsylvania, New York and eastern Ohio (Crispin and Penskar 1990, Cook 1982, Hellquist and Crow 1980). The species is most common in western New England, eastern New York and northern Michigan (Hellquist and Crow 1980).

Potamogeton hillii is found in the highly alkaline, hard-water lakes, ponds and streams of New England (Cook 1982, Hellquist and Crow 1980). Only in Berkshire County, Massachusetts is it locally abundant (Hellquist and Crow 1980). Waters inhabited by P. hillii typically possess an average alkalinity of 148.6 mg bicarbonate/liter, with a range of 53.0 to 290.0 mg/l Calcium carbonate (Hellquist 1984). Readings of pH in these habitats average 7.5, with a range of 7.2 to 8.2 (Hellquist and Crow 1980). Hellquist (1984) later observed through field observation that it could be found:

"in clear, cold, alkaline water in small, slow flowing streams, ponds, and beaver ponds with a muddy substrate. In streams, it often appears on the upstream side of road culverts where more marshy conditions occur. In beaver ponds and marshes, it often grows among stumps and fallen trees, or in shallow water among rushes and sedges. In ponds, P. hillii is occasionally found in deeper waters up to 1.5 meters."

According to Hellquist (1984), the vast majority (94%) of known populations occur in waters over dolomitic limestone or marble. The species is also restricted primarily to clear cold waters, often around springs and small inlets in ponds and marshes (Hellquist 1984). This association with high carbonates has also been noted by Mitchell and Sheviak (1981). Haynes (1974) described the typical habitat as cold, stagnant or slow-moving, often brown, water.

Mitchell and Sheviak (1981) stated that P. hillii is found in situations where aquatic succession is taking place. Consequently, they do not persist at a given location for a long length of time. Typical associates include Potamogeton foliosus, P. natans, P. pusillus var. tenuissimus, P. amplifolius, and P. gramineus. Conversely, it is rarely found with P. strictifolius, P. friesii, and P. pectinatus which are common in more eutrophic waters (Hellquist 1984). For a specific list of all known sites throughout the range of the species as of 1984, see Hellquist (1984).

As of 1984, approximately 12 historical and extant sites were known from the species in New York (Hellquist 1984). Mitchell and Sheviak (1981) stated that the species is restricted to lakeshores, beaver ponds and artificial impoundments in New York, submerged in 1-4 feet of water. Additional habitats include small streams, ponds and ditches within marshlands (Hellquist 1984).

In Connecticut, plants have been found growing in a sandy-bottomed pond in shallow water among cat-tails and in a river (CT NDD 1989).

Massachusetts currently has 32% of all the known P. hillii stations (Sorrie pers. comm.). Weber (1940) found a large population of P. hillii in a small pond at South Egremont, Massachusetts, growing in small, slow-flowing streams which fed the pool. Listed associates included P. natans, Najas flexilis and a species of Chara. Other sites include ponds, flooded marshes, river bordered by Alnus, beaver ponds and swamps (MA NHP 1989, Hellquist 1984). Additional associates include P. foliosus, Carex spp., Eleocharis flexilis and Nymphaea odorata (MA NHP 1989).

In Michigan, P. hillii is known from 11 extant sites (Crispin and Penskar 1990). Habitats include clean, often cool streams or backwaters (occasionally lakes) on sandy, mucky and marly substrates (Crispin and Penskar 1990). Nepstad (1981) described the Michigan habitat as muck/marl-bottomed small lakes, muck-bottomed, slow-moving or stagnant backwaters and lake outlets, sand-bottomed, brown-water streams and sandy lake-margin Scirpus marshes, usually growing in 3-10 dm of water. Associates include Nuphar spp., Potamogeton natans, P. amplifolius, Nymphaea odorata and Chara spp. (Crispin and Penskar 1990), Hippuris vulgaris, Scirpus acutus, Elodea canadensis, Potamogeton pectinatus, P. richardsonii, P. amplifolius, P. gramineus, Typha latifolia, Polygonum amphibium var. stipulaceum, Utricularia sp. and Myriophyllum sp. (MI NFI 1990, Nepstad 1981).

In Ohio, P. hillii was originally discovered in a stagnant pool of water in Ashtabula County (Morong 1880). Later, the species was collected from sites in Portage (Braun 1967, Fernald 1932), Ottawa and Erie Counties (Spooner 1981). Both the Erie and Ottawa County records probably resulted from a misidentification and are not considered reliable (Snyder and Burns 1984, Spooner 1981). The species was believed extirpated from Ohio for several years prior to its rediscovery at Pyamatuning Creek Fen in Ashtabula County in 1982 (Snyder and Burns 1984). Currently, two populations separated by 3 miles occur in the watershed of Pyamatuning Creek (Bissell pers. comm.). Both populations occur in beaver dam impoundments. One population occurs in a tributary to Pyamatuning Creek in water 1 m deep, while the second occurs on the main channel of the creek in water 0.5 m deep. Both sites occur in an area characterized by fen seepage, in highly calcareous, pristine, alkaline water (pH = 8.0). Associates include P. pusillus ssp. tenuisimus, Ceratophyllum demersum and Elodea canadensis (Bissell pers. comm.).

In Vermont, P. hillii is restricted to Bennington and Rutland Counties in the southwestern portion of the state (Fichtel pers. comm.). This highly calcareous area is known as the Valley of Vermont, an area situated between two mountain ranges. Populations have been documented at 13 sites, occurring in streams and ponds. Historic records are also known from Windsor and Orange Counties in the east-central portion of the state, collected in 1913 and 1970, respectively. The Orange County site is listed as a bog, but was likely a fen (Fichtel pers. comm.). Known associates in Vermont include P. natans, Elodea canadensis, Equisetum fluviatile and Rhamnus alnifolia (VT NHP 1989).

In Ontario, extant populations are known from twelve sites scattered across Wellington, Peel and Bruce Counties and the Manitoulin District (Brownell 1984). An additional extirpated population once occurred in Elgin County. Populations are known from sluggish brooks, ditches, streams, swamps and lakes. Hill's pondweed occupies highly calcareous waters within the province.

Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Focus on the preservation of the successional changes within an aquatic system with respect to the ephemeral habitat the species inhabits. Maintenance of high-quality, pollution-free aquatic systems is a must.
Restoration Potential:

The recovery potential of P. hillii has not been addressed in any research program to date. However, due to its inherent periodicity assumed by occupying successional habitats, it can be assumed that the recovery potential of the species is very good. The random appearance and disappearance of the species in its habitat suggests a well-developed and active dispersal regime.

Preserve Selection & Design Considerations:

Since P. hillii is an aquatic species, land protection must address the entire watershed within which an occurrence exists. This is exaggerated by the fact that this species occupies successional habitats and may not remain at a given site for long periods of time. Protection of selected areas within a watershed will not suffice. Reduction and maintenance of low levels of siltation and other forms of pollution is necessary for continued survival within a given watershed.

Management Requirements:

Management needs must focus on the biology of P. hillii, its ephemeral nature (Metzler pers. comm.), and the quality of its habitat. The maximum benefit that can be obtained through management is the retention or enhancement of habitat quality. Since P. hillii is a species inhabiting successional habitats, it is not likely to occur over a long length of time at a single site. Consequently, specific management of a given site is not likely to produce any long-term benefits for the species. Management of an entire watershed within which the species occurs would provide the only real, lasting benefits through water quality and habitat enhancement and maintenance. Although more time-consuming and expensive, this would be the only feasible management worth the effort.

Management for P. hillii must address the watershed within which the species occurs. Protection of water quality and habitat through soil conservation and pollution control measures is essential. Strict measures which would provide for riparian buffer strips, and eliminate risks posed by pesticide, soil erosion and point-source pollution should be adopted. Each could significantly reduce the viability of any population. In some areas, restrictions on development of lakeshores may need to be implemented to ensure the integrity of lakes possessing high-quality habitats.

Monitoring Requirements:

Individual states may see a need to monitor the status of this species due to the degree of rarity within their particular state. In some portions of its range (Massachusetts, etc.), P. hillii has been found to be particularly common and may not require detailed monitoring. Monitoring of habitat quality should also be undertaken at sites where population monitoring is underway.

Populations may be difficult to monitor because of their aquatic habit, particularly if populations are large. Individual clones can cover surface areas of 0.5 meters in diameter and if such clones are numerous, distinguishing between individual clones may be difficult or impossible. In any case, individual counts or estimations of clone abundance should be attempted.

Habitat quality measurements (water quality, alkalinity, temperature, pH, turbidity, presence of pollutants) should be taken at sites where other monitoring activities are underway.

Monitoring Programs:

The Cleveland Museum of Natural History is currently conducting an inventory and monitoring program in northern Ohio and adjacent Pennsylvania for aquatic plants within the glacial lakes of that region. The program started in 1973 and there are plans to inventory all the glacial lakes within the next five years. These sites, including those with P. hillii, will be monitored every 10 years. Contact: James Bissell, Curator of Botany, Cleveland Museum of Natural History, Wade Oval, University Circle, Cleveland, OH 44106. Telephone No. (216) 231-4600 (ext. 219).

Management Research Programs:

The Lakes and Ponds Unit of the Vermont Department of Environmental Conservation has an active aquatic plant survey program which would turn up new P. hillii occurrences in any surveyed lake or pond. The program has been active since 1982 (Bove pers. comm.). Contact: Sue Warren, Water Quality Division, Department of Environmental Conservation. Telephone No. (802) 244-5638.

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: 11Jul1990
NatureServe Conservation Status Factors Author: Ostlie, W.R. (1990); K. Crowley (1995); S.L. Neid (1998).
Management Information Edition Date: 30Jun1990
Management Information Edition Author: WAYNE OSTLIE
Element Ecology & Life History Edition Date: 31Jan1992
Element Ecology & Life History Author(s): ISAAC, J.; W. OSTILE (1990)

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
Help
  • Argus, G.W., K.M. Pryer, D.J. White and C.J. Keddy (eds.). 1982-1987. Atlas of the Rare Vascular Plants of Ontario.. Botany Division, National Museum of National Sciences, Ottawa.

  • Braun, L.E. 1967. The Monocotyledoneae: cat-tails to orchids. Vol. One. Ohio State Univ. Press, Columbus, Ohio. 464 pp.

  • Britton, N. L. and A. B. Brown. 1913. An Illustrated Flora of the Northern United States, Canada, and the British Possessions. 2nd Edition in 3 Volumes. Charles Scribner's Sons, New York. B13BRI01PAUS.

  • Britton, N. L. and A. Brown. 1913. An Illustrated Flora of the Northern United States and Canada. 3 vol. Dover Publications, Inc., N. Y. 2052 pp.

  • Brownell, V. R. 1986. Status report on Hill's pondweed (Potamogeton hillii). Report to the Committee on the Status of Endangered Wildlife in Canada, Ottawa, Ontario. 27 pp.

  • COSEWIC 2005. COSEWIC assessment and update status report on the Hill's pondweed Potamogeton hillii in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 19 pp. (www.sararegistry.gc.ca/status/status_e.cfm).

  • Crispin, S. and M. Penskar. 1990. Potamogeton hillii. Unpublished abstracts, Endangered species manual, Michigan Natural Features Inventory. 2pp.

  • Crow, G.E. 1982. New England's rare, threatened, and endangered plants. USWFS Northeast Region, Newton Corners, MA.

  • Crow, Garrett E. and C. Barre Hellquist. 2000. Aquatic and Wetland Plants of Northeastern North America: A revised and enlarged edition of Norman C. Fassett's a Manual of Aquatic Plants. Volume One: Pteridophytes, Gymnosperms, and Angiosperms: Dicotyledons. The University of Wisconsin Press. Madison, Wisconsin. 536 Pages.

  • Fassett, Norman C. 1940. A Manual of Aquatic Plants, 1st ed. New York: McGraw-Hill. B57FAS01PAUS.

  • Fassett, Norman C. 1940. A Manual of Aquatic Plants. McGraw- Hill Book Company, New York, New York. 382 p.

  • Fernald, M.L. 1932. The Linear-leaved North American Species of Potamogeton Section Axillares in Memoirs of the Gray Herbarium of Harvard University 3: 1-183. A32FER01PAUS.

  • Fernald, M.L. 1932b. The Linear-leaved North American Species of Potamogeton Section Axillares. Memoirs of the American Academy of Arts and Sciences, New Series, 17(1):1-183.

  • Fernald, M.L. 1949. Gray's Manual of Botany, Eighth edition. American Book Co. New York. B49FER01PAUS

  • Fernald, M.L. 1950 Gray's Manual of Botany, 8th ed. American Book Company, New York. 1632 pp.

  • Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.

  • Flora of North America Editorial Committee. 2000. Flora of North America north of Mexico. Vol. 22. Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae. Oxford Univ. Press, New York. xxiii + 352 pp.

  • Flora of North America Editorial Committee. 2000. Flora of North America north of Mexico. Vol. 22. Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae. Oxford Univ. Press, New York. xxiii + 352 pp.

  • Gleason, H.A. & Cronquist, A. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second Edition. The New York Botanical Garden. Bronx, NY 10458. U.S.A. B91GLE01PAUS.

  • Gleason, H.A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. New York Botanical Garden, Bronx, New York. 910 pp.

  • Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.

  • Haynes, R.R. 1974. A Revision of North American Potamogeton Subsection Pusilli: Potamogetonaceae. Rhodora 76:564-649. A74HAY01PAUS.

  • Haynes, R.R. 1974. A Revision of North American Potamogeton Subsection Pusillii (Potamogetonaceae). Rhodora 76: 564-649.

  • Haynes, R.R. 1974. A revision of North American Potamogeton subsection Pusilli (Potamogetonaceae). Rhodora 76: 564-567; 587; 592-593: 624-626.

  • Hellquist, C. B. 1984. Observations of Potamogeton hillii Morong in North America. Rhodora 86:101-111.

  • Hellquist, C.B. 1977. Observations on some Uncommon Vascular Plants in New England. Rhodora 79:445-452. A77HEL01PAUS.

  • Hellquist, C.B. 1977. Observations on some uncommon vascular plants in New England. Rhodora 79:445-452.

  • Hellquist, C.B. 1980. Correlation of alkalinity and the distribution of POTAMOGETON in New England. Rhodora 82(830):331-344.

  • Hellquist, C.B. 1980. Correlation of alkalinity and the distribution of Potamogeton in New England. Rhodora 82: 331-344.

  • Hellquist, C.B. 1984. Observations of Potamogeton hillii Morong in North America 1984. Rhodora 86:101-111. A84HEL01PAUS.

  • Hellquist, C.B. 1984. Observations of Potamogeton hillii Morong in North America. Rhodora 86: 101-111.

  • Hellquist, C.B. and G.E. Crow 1980. Aquatic Vascular Plants of New England: Part 1. Zosteraceae, Potamogetonaceae, Zannichelliaceae, Najadaceae. New Hampshire Agricultural Experiment Station University of New Hampshire. Station Bull. 515.

  • Hellquist, C.B. and G.E. Crow. 1980. Aquatic vascular plants of New England: Part 1. Zosteraceae, Potamogetonaceae, Zannichelliaceae, Najadaceae. New Hampshire Experiment Station, Durham, New Hampshire. 66 p.

  • Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.

  • 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.

  • Martin, A. C. and F. M. Uhler. 1939. Food of game ducks in the United States and Canada. USDA and Technology Bull. 634. 156 pp.

  • McCance, R.M. and Burns, J.F. eds 1984. Ohio Endangered and Threatened Vascular Plants: Abstracts of State-Listed Taxa, Division of Natural Areas and Preserves. Department of Natural Resources, Columbus, Ohio 635p. B84MCC01PAUS.

  • McCance, R.M., Jr., and J.F. Burns, eds. 1984. Ohio endangered and threatened vascular plants: Abstracts of state-listed taxa. Division Natural Areas and Preserves, Ohio Dept. Natural Resources, Columbus. 635 pp.

  • Mitchell, R. S. and C. J. Sheviak. 1981. Rare plants of New York State. New York State Museum, Bull. 445. 96 pp.

  • Mitchell, Richard S. and Gordon C. Tucker. 1997. Revised Checklist of New York State Plants. Contributions to a Flora of New York State. Checklist IV. Bulletin No. 490. New York State Museum. Albany, NY. 400 pp.

  • Morong, C. 1881. Potamogeton hillii, n. sp. Bot. Gaz. 6:290.

  • Morong, Coult. 1881. Potamogeton hillii, n. sp. Bot. Gaz. 6:290. A81MOR01PAUS.

  • Morong, T. 1880. A new species of Potamogeton, with notes upon some published forms. Bot. Gaz. 5: 50-53.

  • Nepstad, D.C. 1981. Potamogeton hillii Morong, Hill's pondweed, (Potamogetonaceae) in Michigan. Michigan Department of Natural Resources: Endangered Species Program, Wildlife Division and Natural Features Inventory. Lansing, MI

  • New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.

  • Oldham, M.J. 1996. COSSARO Candidate V,T,E Species Evaluation Form for Hill's Pondweed (Potamogeton hillii). Unpublished report prepared by Natural Heritage Information Centre for Committee on the Status of Species at Risk in Ontario (COSSARO), Ontario Ministry of Natural Resources. 4 pp.

  • Oldham, M.J. 2005. COSSARO Candidate Species at Risk Evaluation Form for Hills Pondweed (Potamogeton hillii). Natural Heritage Information Centre. Prepared for Committee on the Status of Species at Risk in Ontario (COSSARO), Ontario Ministry of Natural Resources, Peterborough. 12 April, 11 pp.

  • Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.

  • Riley, J.L. 1979. Ontario's Pondweeds (Genus Potamogeton). Ontario Field Biologist 33(2): 1-26.

  • Snyder, D. and J. F. Burns. 1984. Potamogeton hillii Morong. In McCance, R. M. and J. F. Burns (eds.), Ohio Endangered and Threatened Vascular Flora. Ohio Department of Natural Resources, Columbus. 635 pp.

  • Spooner, D. M., A. W. Cusick, B. Andreas and D. Anderson. 1983. Notes on Ohio vascular plants previously considered for listing as federally endangered or threatened species. Castanea 48(4): 250-258.

  • Spooner, D.M. 1981. Ohio Status of Potamogeton hillii Morong. Report submitted to U.S. Fish and Wildlife Service. Ohio Department of Natural Resources, Columbus, OH. 6pp.

  • Voss, E.G. 1965. Some rare and interesting aquatic vascular plant of northern Michigan with special reference to Casino Lake (Schoolcraft Co.). Michigan Botanist 4: 11-24.

  • Weber, W. A. 1940. Potamogeton hillii in Berkshire County, Massachusetts. Rhodora 42: 95.

  • Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://wwws.nyflora.org/, Albany, New York

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