Myriophyllum heterophyllum

Distribution Map: Based on vouchered plant specimens only. View county names by placing the mouse cursor over a particular county.

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Family:	Haloragaceae
Species:	Myriophyllum heterophyllum Michx.
Common Name:	various-leaved water milfoil, variable-leaved water milfoil
Habitat:	Lakes, ponds, and quiet water of streams. Sometimes quite abundant.
Associated Ecological Communities:	**
Growth Habit:	Forb/herb
Duration:	Perennial
Category:	Vascular
Plant Notes:	Early floristic accounts of Myriophyllum heterophyllum in NY considered it to be rare and restricted to the western and central part of the state (Beckwith and Macauley 1896, House 1924, Wiegand and Eames 1926, Zenkert 1934). This is inline with recent assessments of the native range of this species (Thum et al. 2011), which recognize its native distribution as the southeastern Atlantic Coastal Plain and interior continental US. Therefore, in NY, we consider this species native. Reports of this species as well as herbarium documentation indicate that it began to show up in eastern and southeastern NY, as well as New England, as early as the 1930s (Muenscher 1935, Les and Mehrhoff 1999). Currently it is widespread in northern, eastern, and southeastern NY (as well as New England). In this northeastern range, it is considered nonnative and invasive (Les and Mehrhoff 1999, Moody and Les 2002). Because it is considered invasive in this region, New York State regulates it as an invasive species and among other things prohibits its sale. So in NY, this species has the odd circumstance of being considered native and being regulated as a nonnative invasive species, but see below.
Taxonomic Notes:	Molecular data indicates that within the native range there are two divergent clusters of genotypes (lineages), which correspond to plants from the interior continental US and southeastern Atlantic Coastal Plain (Thum et al. 2011). Thum et al. (2011) found that plants in the introduced range in New England and nearby NY were the result of multiple introductions and represent the Atlantic Coastal Plain and continental lineages as well as hybrids between M. heterophyllum and M. laxum. Although this hybrid very likely occurs in NY, documentation has not been found. These three separate groups appear to have different growth characteristics with the Atlantic Coastal Plain lineage and hybrids producing more biomass than the continental lineage (Tavalire et al. 2012). Gene flow between the Atlantic Coastal Plain and continental lineage of M. heterophyllum appears not to occur, even when the two lineages grow together (Tavalire et al. 2012). It is possible that some of the differences between lineages represent cryptic speciation (i.e., there may be more than one species in what is currently called M. heterophyllum) and further research is warranted.
Status:	Native, OBL (NCNE), OBL (EMP), S5 (State Rank), G5 (Global Rank), CoC: 4
References:	**

** Not applicable or data not available.

Classification

Supraordinal	Eudicots
Order	Saxifragales
Family	Haloragaceae
Genus	Myriophyllum
Species	Myriophyllum heterophyllum Michx. - various-leaved water milfoil, variable-leaved water milfoil

Citation

Citation	Myriophyllum heterophyllum Michx.
Basionym:	**
Type:	**

** Not applicable or data not available.

Source

County	Year	Herbaria	Notes	Submission Info
Cayuga		NYFA_1990 Herbarium Name Used: none Myriophyllum heterophyllum
Jefferson		NYFA_1990 Herbarium Name Used: none Myriophyllum heterophyllum
Jefferson	1931	BH Herbarium Name Used: Myriophyllum heterophyllum	Werier (2017) voucher!; W.C. Muenscher & B. Maguire 2427	3/6/2018 - David Werier
Monroe		NYFA_1990 Herbarium Name Used: none Myriophyllum heterophyllum
Niagara	1864	BKL – BKL00058808 Herbarium Name Used: Myriophyllum heterophyllum		2/8/2012 - BKL (Steve Glenn)
Niagara		NYFA_1990 Herbarium Name Used: none Myriophyllum heterophyllum
Niagara	1864	BKL – BKL00058809 Herbarium Name Used: Myriophyllum heterophyllum		2/8/2012 - BKL (Steve Glenn)
Oneida		NYFA_1990 Herbarium Name Used: none Myriophyllum heterophyllum
Ontario	1980	NYS Herbarium Name Used: none Myriophyllum heterophyllum
Orange	1990	NYS Herbarium Name Used: none Myriophyllum heterophyllum
Orange	1999	BKL – BKL00016778 Herbarium Name Used: Myriophyllum heterophyllum		2/8/2012 - BKL (Steve Glenn)
Orange	1997	NYS Herbarium Name Used: none Myriophyllum heterophyllum
Oswego	1997	NYS Herbarium Name Used: none Myriophyllum heterophyllum
Oswego	1997	RCFS – accession # 12450 Herbarium Name Used: Myriophyllum heterophyllum		11/17/2009 - RCFS (Andy Nelson)
Oswego		NYFA_1990 Herbarium Name Used: none Myriophyllum heterophyllum
Rockland	1990	NYS Herbarium Name Used: none Myriophyllum heterophyllum
Saratoga		NYFA_1990 Herbarium Name Used: none Myriophyllum heterophyllum
St. Lawrence	2002	BH Herbarium Name Used: none Myriophyllum heterophyllum		Anne Johnson
Suffolk	1991	OBPF – Log_num: 8409A Herbarium Name Used: none Myriophyllum heterophyllum
Suffolk	1975	OBPF – Log_num: 2020 Herbarium Name Used: none Myriophyllum heterophyllum
Suffolk	1974	OBPF – Log_num: 9182 Herbarium Name Used: none Myriophyllum heterophyllum
Ulster		NYFA_1990 Herbarium Name Used: none Myriophyllum heterophyllum
Wayne		NYFA_1990 Herbarium Name Used: none Myriophyllum heterophyllum

Synonyms

No synonyms exist for this species.

No synonyms exist for this species.

Listed Status: New York

Listed Status:	(New York): Rare plants are protected under New York State Environmental Conservation Law section 9-1503. Part (f) which reads as follows: "It is a violation for any person, anywhere in the state to pick, pluck, sever, remove, damage by the application of herbicides or defoliants, or carry away, without the consent of the owner, any protected plant. Each protected plant so picked, plucked, severed, removed, damaged or carried away shall constitute a separate violation." At this time, the Atlas only identifies those species listed as threatened or endangered.
Endangered: 5 or fewer extant sites, or fewer than 1,000 individuals, or restricted to fewer than 4 U.S.G.S. 7 1/2 minute topographical maps, or species listed as endangered by the U. S. Department of Interior, as enumerated in the Code of Federal Regulations 50 CFR 17.11.
Threatened: 6 to fewer than 20 extant sites, or 1,000 to fewer than 3,000 individuals, or restricted to not less than 4 or more than 7 U.S.G.S. 7 1/2 minute topographical maps, or listed as threatened by the U. S. Department of the Interior, as enumerated in the Code of Federal Regulations 50 CFR 17.11.
Rare: 20 to 35 extant sites, or 3,000 to 5,000 individuals statewide.
Exploitably vulnerable:	species which are likely to become threatened in the near future throughout all or a significant portion of their range within the state if causal factors continue unchecked.

Listed Status: US

Listed Status: US	(U.S.) Source - List of Endangered and Threatened Wildlife and Plants under the provisions of the Endangered Species Act of 1973, as amended.
Endangered:	Any species which is in danger of extinction throughout all or a significant portion of its range.
Threatened:	Any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.

WAP: Wetland AssessmentProcedure

Wetland Assessment Procedure (WAP): Source - Southwest Florida Water Management District, Wetland Assessment Procedure Instruction Manual for Isolated Wetlands (March 2005).

AD:	Adaptive Species. Plant species designated as FAC or Upland by DEP, but commonly seen in the transition zone in limited numbers.
D:	Deep Species. Plant species commonly found in the deep zone, and designated either FAC or OBL by DEP.
OD:	Outer Deep Species. Plant species commonly found in the outer deep zone, and designated either FACW or OBL by DEP.
T:	Transition Species. Plant species commonly found in the transition zone, and designated either FACW or OBL by DEP.
U:	Upland Species. Plant species that are not expected to be seen in wetlands.

ANY - WAP critieria is not taken into consideration
Yes - Show results with WAP designations
No - Show results without WAP designations

EPPC: Exotic Pest Plant Council

EPPC:

Source - Florida Exotic Pest Plant Council's 2007 List of Florida's Most Invasive Species

Category I - Species that are invading and disrupting native plant communities in Florida. This definition does not rely on the economic severity or geographic range of the problem, but on the documented ecological damage caused.

Category II - Species that have shown a potential to disrupt native plant communities. These species may become ranked as Category I, but have not yet demonstrated disruption of natural Florida communities.

DEP: Department of Environmental Protection

Wetland Status, Department of Environmental Regulation (DEP): Source - Delineation of the Landward Extent of Wetlands and Surface Waters, Chapter 62-340, Florida Administrative Code. 1994.

OBL:	Obligate wetland. Occurs almost always under natural conditions in wetlands.
FACW:	Facultative Wetland. Usually occurs in wetlands, but occasionally found in non-wetlands
FAC:	Facultative. equally likely to occur in wetlands or non-wetlands.

NWPL: National Wetland Plant List

National Wetland Plant List (NWPL): Source - Lichvar, R.W., M. Butterwick, N.C. Melvin, and W.N. Kirchner. 2014. The National Wetland Plant List: 2014 Update of Wetland Ratings. Phytoneuron 2014-41: 1-42.

OBL:	Obligate Wetland. Occurs almost always (estimated probability 99%) under natural conditions in wetlands.
FACW:	Facultative Wetland. Usually occurs in wetlands (estimated probability 67%-99%), but occasionally found in non-wetlands.
FAC:	Facultative. Equally likely to occur in wetlands or non-wetlands (estimated probability 34%-66%).
FACU:	Facultative Upland. Usually occurs in non-wetlands (estimated probability 67%-99%), but occasionally found in wetlands (estimated probability 1%-33%).
UPL:	Obligate Upland. Occurs in wetlands in another region, but occurs almost always (estimated probability 99%) under natural conditions in non-wetlands in the regions specified.

NWPL: National Wetland Plant List (NCNE and EMP Regions)

National Wetland Plant List (NWPL): Source - U.S. Army Corps of Engineers 2020. National Wetland Plant List, version 3.5 https://wetland-plants.sec.usace.army.mil/nwpl_static/v34/home/home.html U.S. Army Corps of Engineers, Engineer Research and Development Center, Cold Regions Research and Engineering Laboratory, Hanover, NH.

Indicator status rating definitions according to Lichvar et al. 2012.

OBL:	Obligate Wetland Plants - almost always occur in wetlands.
FACW:	Facultative Wetland Plants - usually occur in wetlands, but may occur in non-wetlands.
FAC:	Facultative Plants - occur in wetlands and non-wetlands.
FACU:	Facultative Upland Plants - usually occur in non-wetlands, but may occur in wetlands.
UPL:	Upland Plants - almost always occur in uplands.

Wetland indicator status ratings are provided for each of the two regions that exist in NY, the Northcentral and Northeast Region (NCNE) and the Eastern Mountains and Piedmont Region (EMP). See the Atlas guide for further details.

NWPL: National Wetland Plant List (NCNE and EMP Regions)

Indicator status rating definitions according to Lichvar et al. 2012.

OBL:	Obligate Wetland Plants - almost always occur in wetlands.
FACW:	Facultative Wetland Plants - usually occur in wetlands, but may occur in non-wetlands.
FAC:	Facultative Plants - occur in wetlands and non-wetlands.
FACU:	Facultative Upland Plants - usually occur in non-wetlands, but may occur in wetlands.
UPL:	Upland Plants - almost always occur in uplands.

Persisting

Identifying species that appear as waifs or only periodically appear in the flora for a few seasons.

Any - Persisting critieria is not taken into consideration
Yes - Show results with a Persisting value of Y
No - Show results without Persisting value of N

Duration

Annual:	Plants that perform their entire lifecycle within a single growing season. All roots, stems, and leaves die at the end of the growing season. Over wintering seeds allow the next generation to appear.
Biennial:	A plant that is typically vegetative its first year and blooms the following season. Once it has bloomed and set seed, the plant dies. Garlic mustard is an example of a biennial.
Perennial:	These plants live for three or more seasons. Many perennials may not be mature enough to bloom during its first year. Perennial wildflowers re-grow each season from overwinter root material.

Category

Vascular:	Any of various plants that have the vascular tissues xylem and phloem. The vascular plants include all seed-bearing plants (the gymnosperms and angiosperms) and the pteridophytes (including the ferns, lycophytes, and horsetails). Also called tracheophyte.
Bryophyte:	A large group of seedless green plants including the mosses, liverworts, and hornworts. Bryophytes lack the specialized tissues xylem and phloem that circulate water and dissolved nutrients in the vascular plants. Bryophytes generally live on land but are mostly found in moist environments, for they have free-swimming sperm that require water for transport. In contrast to the vascular plants, the gametophyte (haploid) generation of bryophytes constitutes the larger plant form, while the small sporophyte (diploid) generation grows on or within the gametophyte and depends upon it for nutrition.
Lichen:	The mutualistic symbiotic association of a fungus with an alga or a cyanobacterium, or both. The fungal component of a lichen absorbs water and nutrients from the surroundings and provides a suitable environment for the alga or cyanobacterium. These live protected among the dense fungal hyphae and produce carbohydrates for the fungus by photosynthesis. Owing to this partnership, lichens can thrive in harsh environments such as mountaintops and polar regions. The more familiar lichens grow slowly as crusty patches, but lichens are found in a variety of forms, such as the tall, plantlike reindeer moss. The association between the different organisms in a lichen is so close that lichens are routinely referred to as a single organism, and scientists classify lichens using the name of the fungal component.

(Definitions from: American Heritage Science Dictionary)

Growth Habit

Intro paragraph to be provided by New York.

Vine:	DESCRIPTION TO BE PROVIDED BY NEW YORK.
Shrub:	DESCRIPTION TO BE PROVIDED BY NEW YORK.
Tree:	DESCRIPTION TO BE PROVIDED BY NEW YORK.
Et cetera:	DESCRIPTION TO BE PROVIDED BY NEW YORK.

State Rank

This numeric rank provides the relative rarity for each species based on a scale from 1 (very rare) to 5 (common). These ranks carry no legal status.

S1 - Typically 5 or fewer occurrences, very few remaining individuals, acres, or miles of stream, or some factor of its biology making it especially vulnerable in New York State.
S2 - Typically 6 to 20 occurrences, few remaining individuals, acres, or miles of stream, or factors demonstrably making it very vulnerable in New York State.
S3 - Typically 21 to 100 occurrences, limited acreage, or miles of stream in New York State.
S4 - Apparently secure in New York State.
S5 - Demonstrably secure in New York State.
SE - State exotic or non-native
SH - Historically known from New York State, but not seen in the past 15 years.
SNA - Species for which a rank is not applicable. This is mainly those species which are now excluded from flora for various reasons.
SNR - Not yet ranked
SX - Apparently extirpated from New York State.

Global Rank

Each species' global rank is determined by NatureServe. These ranks carry no legal weight. The global rank reflects the species worldwide rarity.

G1 - Critically Imperiled — At very high risk of extinction or elimination due to very restricted range, very few populations or occurrences, very steep declines, very severe threats, or other factors.
G2 - Imperiled — At high risk of extinction or elimination due to restricted range, few populations or occurrences, steep declines, severe threats, or other factors.
G3 - Vulnerable — At moderate risk of extinction or elimination due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors.
G4 - Apparently Secure — At fairly low risk of extinction or elimination due to an extensive range and/or many populations or occurrences, but with possible cause for some concern as a result of local recent declines, threats, or other factors.
G5 - Secure — At very low risk of extinction or elimination due to a very extensive range, abundant populations or occurrences, and little to no concern from declines or threats.
GH - Possibly Extinct — Known from only historical occurrences but still some hope of rediscovery. Examples of evidence include (1) that a species has not been documented in approximately 20-40 years despite some searching and/or some evidence of significant habitat loss or degradation; (2) that a species has been searched for unsuccessfully, but not thoroughly enough to presume that it is extinct or eliminated throughout its range.
GNA - Not Applicable — A conservation status rank is not applicable because the species is not a suitable target for conservation activities. A global conservation status rank may be not applicable for several reasons, related to its relevance as a conservation target. Typically the species is a hybrid without conservation value, or of domestic origin.
GNR - Global rank not yet assessed.
GX - Presumed Extinct — Not located despite intensive searches and virtually no likelihood of rediscovery.

Filter by County - Counties to Include - ANY versus ALL

Any - An Any search will combine the list of counties to include with a Boolean Or. Plant species returned will be found within at least one of the selected counties.
All - An All search will combine the list of counties to include with a Boolean And. Plant species returned will be found within each of the selected counties.

Filter by County - Counties to Exclude - ANY versus ALL

Any - An Any search will combine the list of counties to exclude with a Boolean Or. Plant species returned will not be found within at least one of the selected counties.
All - An All search will combine the list of counties to exclude with a Boolean And. Plant species returned will not be found within any of the selected counties.

Associated Ecological Communities

View a List of All Ecological Communities

For more information, contact: David Werier or Kyle Webster

Web Development: USF Water Institute

A member of the University of South Florida family of PlantAtlas.org sites

Citation Information:

Werier, David, Kyle Webster, Troy Weldy, Andrew Nelson, Richard Mitchell†, and Robert Ingalls†. 2024 New York Flora Atlas. [S. M. Landry and K. N. Campbell (original application development), USF Water Institute. University of South Florida]. New York Flora Association, Albany, New York.

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Definition: Vouchered Specimen

A voucher specimen is a pressed and thoroughly dried plant sample deposited in a herbarium, and is intended to be a permanent record supporting research purposes. A voucher may be a record of a plant's occurrence in a particular area, or a specific example of a plant used in a scientific investigation.

Proper vouchers display all the necessary attributes for complete identification of the plant, and are to be accompanied by accurate locality, habitat, collection time, and collector data.

Only plant populations vouchered by specimens deposited in Index Herbariorum (http://sweetgum.nybg.org/science/ih/) recognized herbaria are represented on this map.

Myriophyllum heterophyllum

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Classification

Citation

Source

Synonyms