floristic reevaluation of a created wetland in portsmouth, new hampshire

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Floristic reevaluation of a created wetland inPortsmouth, New HampshireAuthor(s): Kassandra J. Jahr and Garrett E. CrowSource: Rhodora, 107(929):87-102. 2005.Published By: The New England Botanical Club, Inc.DOI: http://dx.doi.org/10.3119/04-12.1URL: http://www.bioone.org/doi/full/10.3119/04-12.1

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RHODORA, Vol. 107, No. 929, pp. 87–102, 2005

FLORISTIC REEVALUATION OF A CREATED WETLAND

IN PORTSMOUTH, NEW HAMPSHIRE

KASSANDRA J. JAHR AND GARRETT E. CROW1

Department of Plant Biology, University of New Hampshire,

Durham, NH 038241e-mail: [email protected]

ABSTRACT. Long-term reassessment of floristic diversity in created wetlands is

needed to gain an understanding of how wetlands created for mitigation mature

floristically. A thorough floristic survey of a 17-year old created wetland in

southeastern New Hampshire was conducted to compare current data to a 1992

floristic study of the site. The flora in 2002 included 110 species, whereas the total

number of species recorded in 1992 was 101. Not only had diversity increased, but

the flora had changed in a 10-year span; the floristic lists of the two years showed 79

shared species. Sørensen’s Index of Similarity revealed a floristic similarity of 75%.

Carex atherodes, new to the site in 2002, represents a new state record for New

Hampshire. As there is a great need for long-term evaluation of mitigation wetlands,

these data contribute toward a better understanding of the maturation of created

wetlands, and can be used to make more meaningful floristic comparisons with

natural wetlands and evaluate the long term success of wetland mitigation projects.

Key Words: created wetlands, wetland mitigation, floras, floristic diversity, aquatic

plants, wetland vegetation, similarity index

Wetland creation, as compensation for wetlands lost through

commercial and private development, is an endeavor that has increased

in frequency since the 1990s. While a substantial body of literature on

wetland mitigation is developing, most papers are based on short-term

studies. Thus, a paucity of research on the longer-term outcome of these

projects has left a void in the wetland mitigation knowledge base. Little

appears to be known as to how created wetlands mature, or if they will

develop as designed, thus ultimately achieving the mitigation goals.

Furthermore there is a general lack of information, especially in-

corporating total botanical inventories, on how the floristic diversity of

created wetlands change as they age. If resource managers are to have

confidence in wetland creation as a mitigation tool, then documenting the

flora and understanding the changes that take place in species

composition over time during the maturation of diverse wetland

communities is sorely needed.

Mitigation projects are becoming larger and more complex as the field

of mitigation grows. One goal of wetland mitigation is to create

87

a wetland such that the biodiversity (species richness) is comparable to

an undisturbed wetland, or to the type of wetland it was created to

replace (Brown and Veneman 2001; Mitsch and Gosselink 2000;

Whigham 1999). Whigham (1999) observed that although efforts to

create ‘‘in kind’’ wetlands are taking place, the replacements are often

floristically vastly different from natural wetlands. Research in floristic

diversity in mitigation wetlands is limited (Atkinson et al. 1993; Padgett

and Crow 1993a; Reinartz and Warne 1993), yet badly needed.

Long term evaluation of created wetlands is another area lacking in

research (Atkinson et al. 1993; La Peyre et al. 2001; Reinartz and Warne

1993), resulting in a gap in our understanding of floristic development

over time. Although functional mitigation success is estimated to take

15–20 years in some cases, typically little monitoring of mitigation

projects in the United States is conducted after the third or fourth

growing season (Brown and Veneman 2001; Cole 2002; Dennison

1997). In the case of a forested wetland, successful establishment can

conceivably take a human lifetime to attain (Mitsch and Gosselink

2000). Long term evaluation of created wetlands is needed to ensure that

creation projects are successful, and to establish baseline data on floristic

maturation. Toward that purpose we reevaluated the species richness/

floristic diversity of a created wetland previously studied in 1992, and

assessed changes in the flora after 10 years of maturation.

SITE DESCRIPTION

The mitigation wetland was created as a 13-acre freshwater wetland

complex located within the City of Portsmouth, New Hampshire,

approximately one mile south of Lang Road on Route 1 during the

winter of 1985–86 (Garlo 1992; Padgett 1993; Padgett and Crow 1994).

It was created as compensation for wetlands lost in the expansion of the

Portsmouth Regional Hospital’s parking area.

The mitigation site was chosen by the Portsmouth Conservation

Commission primarily due to proximity to another conservation land

parcel, and location adjacent to a natural forested wetland. The site was

an abandoned gravel pit, badly degraded, and therefore in need of

habitat enhancement. Construction of the wetland consisted of land

excavation to groundwater level in the degraded areas to create

depressional areas (pools) linked by channels. The pools averaged

approximately 2 meters at their deepest. Several areas designated as

‘‘Mixed Forested Wetland’’ and ‘‘Deciduous Shrub Wetland’’ were

88 Rhodora [Vol. 107

protected during construction as sanctuary for wildlife and as additional

seed sources for revegetation, and would remain as terrestrial areas

between depressional pools (Garlo 1992).

Muck soils were translocated from the impacted wetland and spread

as a thin layer at the created site to increase nutrient and organic content

of the soils, as well as provide a natural seed and propagule cache (Garlo

1992). Natural revegetation was then allowed to occur. However, this

was augmented by plantings of native shrubs from a preselected list of

species. The original mitigation plan also allowed for additional

plantings at the discretion of the planners if sufficient vegetation had

not been established by the end of the first growing season (Padgett and

Crow 1994).

The hydrology of the wetland was not influenced by any streamlet

inflow, and was regulated mainly by inputs from runoff and groundwater

discharge. Beaver activity, however, blocked the small outlet stream on

the western side of the site, thus increasing the actual water level of the

wetland by approximately two feet over the designed level (Garlo 1992).

Such alterations of hydrology by beaver in created wetlands are well

documented (Cronk and Fennessy 2001; Hammer 1992).

The primary goal of this mitigation project was to create suitable

wildlife habitat, but not necessarily to increase biodiversity (Normandeau

Associates, Inc., Bedford, NH, unpubl. report, 1986). Mitigation

requirements for this project did not include specifications for monitoring

reports, so limited data on changes in the wetland exist before the 1992

study by Padgett and Crow (Garlo 1992; Padgett and Crow 1994).

MATERIALS AND METHODS

Floristic study. The botanical investigation in 2002 was carried out

at the site during the 17th growing season after creation in order to

establish a total inventory of plant species for the created wetland. To

ensure a thorough inventory, all macro- and micro-vegetation types

throughout the wetland were examined, rather than restricting sampling

to transects. Sampling and collecting of voucher specimens to document

the flora was conducted from the beginning of June through the end of

August. The site was visited at least once every 10 days to ensure the

inclusion of all plants in good fertile condition as they matured through

the season.

The primary references for plant identifications were Aquatic andWetland Plants of Northeastern North America (Crow and Hellquist

2005] Jahr and Crow—Floristic Reevaluation of Created Wetland 89

2000a, 2000b), and Manual of Vascular Plants of Northeastern UnitedStates and Adjacent Canada (Gleason and Cronquist 1991). Voucher

specimens were deposited in the Hodgdon Herbarium (NHA) at the

University of New Hampshire, as was the case in the 1992 study

(Padgett and Crow 1994).

Indices of similarity. Sørensen’s Index of Similarity was used to

assess the similarity of species composition between the 1992 and the

2002 floras by calculating the number of species shared. Sørensen’s

Index (Mueller-Dombois and Ellenberg 1974) is calculated as follows:

Sørensen’s Index ¼ ½2c 4 ðaþ bÞ�3 100

where (c) is the number of species shared and (aþ b) is the total number

of the two floras. Sørensen’s Index of Similarity was calculated

comparing the total floras in 1992 (Padgett and Crow 1994) and 2002.

Comparison of community composition and structure. Al-

though a plot-based community analysis was not conducted, it was

possible to assess abundance as part of the floristic inventory. The

vegetation map from the 1992 study was utilized to determine if the

vegetation cover types reported by Padgett and Crow (1994) were still

recognizable, or if changes in species dominance in those cover types

had occurred.

RESULTS

Floristic study. In 2002 the wetland consisted of several depres-

sional pools, which tended to be dominated by Potamogeton natans and

P. amplifolius (Pondweeds), with the westernmost pool having an

abundance of Brasenia schreberi (Water-shield). Some of these pools

were connected by shallow channels that were characterized by a dense

growth of Sparganium eurycarpum (Bur-reed), S. americanum, and

Pontederia cordata (Pickerel-weed). Several upland ‘‘islands’’ occurred

scattered among the depressional pools and were characterized by

terrestrial vegetation of trees, shrubs, and other mesic species. A moat-

like channel occurred along the northwestern side of the wetland,

serving as the limit of the created wetland on that side. Several plant

communities surrounded the created wetland. To the west a natural low,

wet Acer rubrum (Red Maple) woods with an abundance of

Symplocarpus foetidus (Skunk Cabbage) occurred, whereas the


southeastern border of the wetland consisted of a steep bank, sparsely

planted with Pinus strobus (White Pine), and a dry, sandy area of highly

disturbed open upland. The northeastern border was a buffer strip

consisting of a steep wooded hillside with Robinia pseudoacacia (Black

Locust), among other tree species, that separated the created wetland

from residential apartments.

The vascular flora of the wetland in 2002 consisted of 110 plant

species, whereas the survey conducted in 1992 (Padgett and Crow 1994)

reported 101 species (Table 1). Of the 101 species documented in 1992,

22 species were not recorded in the 2002 study. One notable absence

from the 2002 study was Najas minor, a submersed aquatic species that

was reported as a new state record for New Hampshire (Padgett and

Crow 1993b, 1994); considered an invasive species, this annual plant

has disappeared. Thirty-one species recorded in 2002 were not present

in 1992. Notable species included Typha 3glauca, a hybrid of T.latifolia and T. angustifolia, and Carex atherodes, a rare plant in New

England and a new state record for New Hampshire (Jahr and Crow

2004).

Based on a reexamination of voucher specimens, two species found in

1992 were determined to have been misidentified. Alisma subcordatumwas reported as A. triviale in the 1992 study; Myrica pensylvanica was

misidentified as M. gale. These appear corrected on Table 1. Three

species included in the 1992 flora (Padgett and Crow 1994), Solidagorugosa, Panicum rigidulum, and P. villosissimum, were deemed to be

marginal terrestrial species by the first author, and therefore excluded

from the 1992 list on Table 1.

Similarities of floras. With floristic totals of 101 in 1992 and 110

species in 2002, not only had diversity increased, but the flora had

changed in a 10-year span; the floristic lists of the two years showed 79

shared species. Sørensen’s Index of Similarity, employed to determine

the floristic similarity after ten years of maturation, revealed a 75%

similarity between the two total floras.

Comparison of community composition and structure. The

plant communities and their distributions recognized in the 1992 study

(Padgett and Crow 1994) appear to have changed in the past 10 years. In

1992, seven vegetation cover types (CT) in two groups were identified.

Open Water Cover Types included Potamogeton natans CT, Chara sp.

CT, and P. pusillus CT; Emergent Cover Types included Juncuseffusus–Phalaris arundinacea CT, Typha latifolia CT, Carex stricta CT,


and Eleocharis smallii CT. Overall, the species that dominated these

plant communities were still a major presence in the wetland’s landscape

in 2002, with an increased abundance of several other species. The only

true replacement of a 1992 cover type was Brasenia schreberi replacing

the Chara sp. as a cover type. Although Chara sp. (a macrophytic alga)

was still encountered, it was not considered abundant, whereas

B. schreberi was very abundant in several of the westernmost depres-

sional pools.

DISCUSSION

Comparison of floras. Floristic studies provide a ‘‘snap-shot’’ of

the species present in a landscape at a particular point in time. However,

floras can change over time due to ecological shifts as well as human-

induced stresses (Oredsson 2000). Therefore, a total floristic study

reassessing floristic diversity has provided an opportunity to gain some

understanding of the maturation of a created wetland.

The difference in floristic composition between the two evaluations

was most likely due to the fact that the site was a relatively young

wetland. It has been suggested that created wetlands take at least 15–20

years to mature into fully-functioning, stable wetlands (Atkinson and

Cairns 2001; Atkinson et al. 1993; Mitsch and Gosselink 2000). Thus,

the Portsmouth site in 2002, at year 17 from creation, would still be in

the maturation phase of its development. Floristic composition may

continue to change as the wetland advances in age. However, Brown

and Veneman (2001) found no evidence that the created wetlands within

their study in Massachusetts were becoming more similar to natural

wetlands as they matured. Over the next decade, soil conditions can be

expected to develop anaerobic characteristics (Cronk and Fennessy

2001) and to accumulate additional organic matter, becoming more like

soils characteristic of natural wetlands (Atkinson and Cairns 2001;

Mitsch and Gosselink 2000). Atkinson and Cairns (2001) found that the

rate of decomposition in the soil litter of a 20-year-old created wetland

was greater than that of one that was only 2 years old. However,

decomposition rates still lagged behind those that were reported for

natural wetlands. Hydrology may change as organic matter builds in

emergent and open-water zones of the wetland (Mitsch and Gosselink

2000; Zentner 2001). Soil conditions affect floristic composition of

wetlands in turn.

At the Portsmouth site, there had already been substantial losses and

gains of species in just 10 years time. Of the 22 species lost, 10 were


characterized in the 1992 study as ‘‘uncommon’’ (Padgett and Crow

1994). For these species to be absent from the flora 10 years later was

not surprising. Of the ‘‘uncommon’’ species only Hypericum canadenseand Echinochloa crusgalli were annuals (U.S.D.A., NRCS 2002).

Echinochloa crusgalli, a non-native species widespread throughout

North America (Gleason and Cronquist 1991) is considered a weed in

the Northeast (Uva et al. 1997). This species of disturbed sites was low

in abundance in 1992 and most likely disappeared as the wetland

matured and other wetland species became established. The disappear-

ance of H. canadense in this wetland may be linked to the fact that it is

typically an annual or short-lived perennial species (Gillett and Robson

1981), often in disturbed soils. The remainder of the ‘‘uncommon’’species no longer present in 2002 were short-lived perennials (U.S.D.A.,

NRCS 2002). Species unable to establish and maintain viable

populations are quite likely to be lost from an ecosystem (Smith

1992), and these had apparently simply died out. This would be in line

with the findings of a study of primary succession in created wetlands in

Virginia by DeBerry and Perry (2004) whereby annuals comprised

a very high percentage (49.1%) of the species of created wetlands in

Virginia, in contrast to a mere 3.7% of the flora consisting of annuals in

their natural reference wetland.

The disappearance of long-lived perennial species abundant in 1992

were more difficult to explain. It was not clear why species such as

Eleocharis obtusa (Blunt Spike-rush) and Juncus articulatus (Jointed

Rush), described as being both frequent throughout the wetland and

locally abundant in 1992 (Padgett and Crow 1994), would not have

persisted 10 years later. Two other common species, Viola lanceolata(Lance-leaved Violet) and Dulichium arundinaceum (Three-way

Sedge) described as being locally abundant in the 1992 study (Padgett

and Crow 1994), have also disappeared from the site. However, with the

exception of D. arundinaceum, we have noted that these tend to be

pioneer species, occurring primarily on sites with sparse cover, and

therefore might be expected to be impacted by greater establishment of

vegetation on such open sites. This appears to be borne out by the studies

of DeBerry and Perry (2004).

Several species present in 2002, but not encountered in the 1992

survey, are noteworthy. Brasenia schreberi (Watershield) is a species

that is now predominant in one area of the wetland. The ‘‘sudden’’abundant appearance of B. schreberi may have resulted from seeds that

had been part of the seed bank in the soils translocated from the

impacted wetland, but conditions within the newly created wetland may


not have initially been favorable for germination. On the other hand, B.schreberi is also a fairly common food for waterfowl. It is reported that

the species is used by ducks as food, and can be a locally important

food source in some areas (Fassett 1940; Martin and Uhler 1939).

Thus, this species may have been dispersed into the wetland by

waterfowl.

Another interesting new and abundant occurrence was Sparganiumamericanum (Burreed). The fruits of S. americanum exhibit hydrochory,

having a pericarp with large intercellular chambers allowing the seeds to

float (Cronk and Fennessy 2001). With no inflow to the wetland,

hydrochory can account for only local dispersion. Thus, a more likely

vector of dispersal in this case is wildlife, since the nutlets of this species

are a common food for wildfowl, and often are preferred by deer (Fassett

1940; Martin and Uhler 1939).

Comparison of community composition and structure. While

the species that dominated the plant communities recognized in the 1992

study were still a major presence in the wetland’s landscape, some

vegetation cover types could be renamed as a result of the 2002 as-

sessment. The Potamogeton natans CT recognized in 1992 (Padgett and

Crow 1994) remained, but P. amplifolius codominated in 2002. The P.pusillus CT was concentrated in one small area in 1992, but the species

was abundant enough in 2002 to codominate, or exist as a subdominant

species within other open water areas.

The Eleocharis smallii (Spike-rush) CT and the Carex stricta CT

remained largely unchanged. Interestingly, the E. smallii CT area had

a peaty substrate and therefore supported several peatland plant

species, including Drosera intermedia (Sundew), Vaccinium macro-carpon (Cranberry), and Sphagnum sp. (Sphagnum Moss), and was

restricted to a relatively small section of the wetland. These

occurrences were also reported in the 1992 study (Padgett and Crow

1994), and although they remained scarce in the landscape in 2002,

they did persist.

The vegetation cover type dominated by Typha latifola (Common

Cattail) was, and continued to be, a predominant feature in the wetland.

Differing from the 1992 study, however, were the codominants and

subdominants identified within this plant community. Among the

differences was the conspicuous presence of Typha 3glauca. Sev-

eral species in 2002 were found to be abundant or frequent and oc-

curred almost exclusively within the dense Typha stands. For instance,

both Proserpinaca palustris (Mermaid-weed) and Ludwigia palustris


(Water-purslane) were found inhabiting the emergent areas within the

Typha stands, the former an amphibious plant of shallow waters and the

latter floating in the shallow waters, between the thick Typha stems.

Commonly found within the less inundated Typha stands was Galiumpalustre (Marsh-bedstraw), as well.

One vegetation cover type that appeared to have changed significantly

since 1992 was the Juncus effusus–Phalaris arundinacea CT. This cover

type was one of the most diverse floristically in the 1992 study. The

largest change in this community involved species abundance and extent

within the wetland. In 2002, this cover type was less abundant than in

1992 (Padgett and Crow 1994). Although still common, in 2002 it was

not a codominant. Species that had gained in abundance within this cover

type included Lythrum salicaria (Purple Loosestrife) and Calamagrostiscanadensis (Bluejoint).

Much of the extent of the Juncus effusus–Phalaris arundinacea CT

had been taken over by a new set of emergent species. While the

J. effusus–P. arundinacea CT had extended somewhat into the Typhalatifolia CT on the northern side of the wetland, Sparganiumeurycarpum, S. americanum, and Pontederia cordata were predominant

in the shallow channels between depressional pools throughout the

wetland. Although a rare species in the state of New Hampshire (New

Hampshire Natural Heritage Bureau 2003), S. eurycarpum, a clonal

species, can form extensive rhizomatous monocultures (Cronk and

Fennessy 2001). This capability may enable S. eurycarpum to achieve

greater dominance in the future.

Overall, the species composition of the communities, the levels of

dominance of principal species, and the dispersion of diversity resulted

in a changed wetland. Since most literature on wetland mitigation has

focused on short-term studies, this data contributes to a better

understanding of the maturation of created wetlands. There is a great

need for long-term evaluation of mitigation wetlands in order to be

able to make more meaningful floristic comparisons with natural

wetlands and for assessing the long-term success of wetland mitigation

projects.

ACKNOWLEDGMENTS. We are grateful to Drs. Janet R. Sullivan and

David M. Burdick, and two anonymous reviewers for their helpful

comments on the manuscript. Geoff Terragni served as an undergraduate

field assistant. This paper is Scientific Contribution No. 2245 of the New

Hampshire Agriculture Experiment Station; financial support from the

AES is gratefully acknowledged.


Table 1. Comparison of species encountered in a created wetland in Portsmouth,

NH, 1992 versus 2002.

Taxon 1992 2002

PTERIDOPHYTES

DRYOPTERIDACEAE

Onoclea sensibilis L. X X

EQUISETACEAE

Equisetum arvense L. X X

OSMUNDACEAE

Osmunda cinnamomea L. X

Osmunda regalis L. X X

THELYPTERIDACEAE

Thelypteris palustris Schott X X

ANGIOSPERMS – DICOTYLEDONS

ACERACEAE

Acer rubrum L. X X

ANACARDIACEAE

Toxicodendron vernix (L.) Kuntze X

APIACEAE

Cicuta bulbifera L. X X

Sium suave Walter X X

AQUIFOLIACEAE

Ilex verticillata L. X X

ASCLEPIADACEAE

Asclepias incarnata subsp. pulchra(Ehrh. ex Willd.) Woodson

X X

ASTERACEAE

Aster lanceolatus var. simplex (Willd.) A.G. Jones X

Aster racemosus Elliott X X

Bidens connatus Muhl. ex Willd. X X

Bidens cf. frondosus L. X X

Eupatorium dubium Willd. ex Poir. X

Eupatorium perfoliatum L. X X

Euthamia graminifolia (L.) Nutt. ex Cass. X X

BALSAMINACEAE

Impatiens capensis Meerb. X X

BETULACEAE

Alnus incana subsp. rugosa (Du Roi) Clausen X X

CABOMBACEAE

Brasenia schreberi J.F. Gmel. X


Table 1. Continued.

Taxon 1992 2002

CALLITRICHACEAE

Callitriche verna (¼ C. palustris L.) X X

CAMPANULACEAE

Campanula aparinoides Pursh X

CLUSIACEAE

Hypericum boreale (Britton) E.P. Bicknell X X

Hypericum canadense L. X

Hypericum dissimulatum E.P. Bicknell X

Hypericum ellipticum Hook. X X

Hypericum mutilum L. X

Triadenum fraseri (Spach) Gleason X X

CORNACEAE

Cornus amomum subsp. obliqua (Raf.)

J.S. Wilson

X X

Cornus stolonifera Michx. X X

DROSERACEAE

Drosera intermedia Hayne X X

ERICACEAE

Lyonia ligustrina (L.) DC. X X

Vaccinium corymbosum L. X X

Vaccinium macrocarpon Aiton X X

HALORAGACEAE

Proserpinaca palustris L. X X

LAMIACEAE

Lycopus americanus Muhl. ex Barton X

Lycopus uniflorus Michx. X X

Scutellaria galericulata L. X X

LENTIBULARIACEAE

Utricularia gibba L. X

Utricularia minor L. X X

Utricularia vulgaris L. X

LYTHRACEAE

Lythrum salicaria L. X X

MYRICACEAE

Myrica pensylvanica Loisel. X X

NYMPHAEACEAE

Nuphar variegata Engelm. ex Durand X X


Table 1. Continued.

Taxon 1992 2002

ONAGRACEAE

Epilobium ciliatum Raf. subsp. ciliatum X

Epilobium palustre L. X

Ludwigia palustris (L.) Elliott X X

POLYGONACEAE

Polygonum amphibium var. emersum Michx. X X

Polygonum arifolium L. X

Polygonum lapathifolium L. X X

Polygonum pensylvanicum L. X

Polygonum punctatum Elliott var. punctatum X X

Polygonum sagittatum L. X X

Rumex crispus L. X

Rumex cf. pallidus Bigelow X

Rumex cf. verticillatus L. X

PRIMULACEAE

Lysimachia terrestris (L.) Britton,

Sterns & Poggenb.

X X

RANUNCULACEAE

Ranunculus sceleratus L. subsp. sceleratus X

RHAMNACEAE

Rhamnus frangula L. X

ROSACEAE

Rosa palustris Marshall X

Spiraea latifolia (Aiton) Borkh. X X

Spiraea tomentosa L. X X

RUBIACEAE

Galium palustre L. X X

SALICACEAE

Salix eriocephala Michx. X

Salix lucida Muhl. X

Salix nigra Marshall X X

SAXIFRAGACEAE

Penthorum sedoides L. X X

SCROPHULARIACEAE

Agalinis purpurea (L.) Pennell X X

Chelone glabra L. X

Mimulus ringens L. X X

SOLANACEAE

Solanum dulcamara L. X X


Table 1. Continued.

Taxon 1992 2002

URTICACEAE

Boehmeria cylindrica (L.) Sw. X X

VERBENACEAE

Verbena hastata L. X X

VIOLACEAE

Viola lanceolata L. X

ANGIOSPERMS – MONOCOTYLEDONS

ALISMATACEAE

Alisma subcordatum Raf. X X

Sagittaria latifolia Willd. X X

ARACEAE

Symplocarpus foetidus (L.) Nutt. X

CYPERACEAE

Carex atherodes Spreng. X

Carex canescens L. X

Carex comosa Boott X X

Carex lenticularis Michx. X

Carex lupulina Willd. X X

Carex lurida Wahlenb. X X

Carex pseudocyperus L. X X

Carex scoparia Schkuhr ex Willd. X X

Carex stipata Muhl. ex Willd. X

Carex stricta Lam. var. stricta X X

Carex utriculata Boott X

Carex vulpinoidea Michx. X X

Cyperus strigosus L. X X

Dulichium arundinaceum (L.) Britton X

Eleocharis acicularis (L.) Roem. & Schult. X X

Eleocharis elliptica Kunth X

Eleocharis obtusa (Willd.) Schult. X

Elecocharis smallii Britton X X

Eleocharis tenuis (Willd.) Schult. var. tenuis X

Rhynchospora capitellata (Michx.) Vahl X

Scripus atrocinctus Fernald X X

Scripus cyperinus (L.) Kunth X X

Scripus hattorianus Makino X

Scripus pungens Vahl X X

Scripus tabernaemontani K.C. Gmel. X X

HYDROCHARITACEAE

Vallisneria americana Michx. X


Table 1. Continued.

Taxon 1992 2002

IRIDACEAE

Iris versicolor L. X X

Sisyrinchium atlanticum E.P. Bicknell X

JUNCACEAE

Juncus acuminatus Michx. X

Juncus articulatus L. X

Juncus canadensis J. Gay X

Juncus effusus L. X X

LEMNACEAE

Lemna minor L. X X

Wolffia columbiana Karst. X

NAJADACEAE

Najas gracillima (A. Br.) Magnus X

Najas minor All. X

POACEAE

Calamagrostis canadensis (Michx.) P. Beauv. X X

Echinochloa crusgalli (L.) P. Beauv. X

Glyceria borealis (Nash) Batch. X

Glyceria canadensis (Michx.) Trin. X X

Leersia oryzoides (L.) Sw. X

Phalaris arundinacea L. X X

Poa palustris L. X X

PONTEDERIACEAE

Pontederia cordata L. X X

POTAMOGETONACEAE

Potamogeton amplifolius Tuck. X X

Potamogeton bicupulatus Fernald X

Potamogeton foliosus Raf. X

Potamogeton natans L. X X

Potamogeton pusillus subsp. tenuissimus(Mert. & Koch) R.R. Haynes & Hellq.

X X

SPARGANIACEAE

Sparganium americanum Nutt. X

Sparganium eurycarpum Engelm. in A. Gray X X

TYPHACEAE

Typha angustifolia L. X X

Typha latifolia L. X X

Typha 3glauca Godr. X

TOTAL SPECIES 101 110


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