Cyperus houghtonii - Torr.
Houghton's Umbrella-sedge
Taxonomic Status: Accepted
Related ITIS Name(s): Cyperus houghtonii Torr. (TSN 39932)
Unique Identifier: ELEMENT_GLOBAL.2.148502
Element Code: PMCYP061L0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Sedge Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Cyperales Cyperaceae Cyperus
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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: Cyperus houghtonii
Conservation Status
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NatureServe Status

Global Status: G4?
Global Status Last Reviewed: 10Sep2002
Global Status Last Changed: 13Mar1994
Rounded Global Status: G4 - Apparently Secure
Reasons: This species appears to be rare or uncommon throughout its wide northeastern and midwestern range.
Nation: United States
National Status: NNR
Nation: Canada
National Status: N3 (03Dec2017)

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 Illinois (S2), Indiana (S2), Maine (SH), Maryland (S1), Massachusetts (S1), Michigan (S3), Minnesota (S3), New Hampshire (S1), New York (S3), North Carolina (SH), Pennsylvania (S1), Vermont (S2), Virginia (SH), West Virginia (S1), Wisconsin (SNR)
Canada Manitoba (S2S3), Ontario (S3), Quebec (S3)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Minnesota, Wisconsin, Michigan, Indiana, Vermont, New Hampshire, Massachusetts, Pennsylvania, Maryland, Virginia, North Carolina; historic in Maine and Ohio; also in Ontario, Manitoba, and Quebec.

Number of Occurrences: 81 to >300
Number of Occurrences Comments: Thirteen-plus occurrences: Maryland - two occurrences, Michigan - eleven locations. Mapped at 62 localities in Wisconsin and known from 15 extant localities in Ontario (fide Ontario CDC, letter 23Feb94).

Overall Threat Impact Comments:

The threats to this plant that have been cited by biologists familiar with its habitat are destruction of natural habitat, fire suppresion and/or succession, trampling by hikers, and off-road vehicles. The notion of "destruction of natural habitat" needs careful, case-by-case evaluation, however. Some activities that would be considered destructive, and may be regarded as threats to this or other plants, may in fact be beneficial to the species. Such activities could include logging, sand/gravel extraction, or off-road vehicle use.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Minnesota, Wisconsin, Michigan, Indiana, Vermont, New Hampshire, Massachusetts, Pennsylvania, Maryland, Virginia, North Carolina; historic in Maine and Ohio; also in Ontario, Manitoba, and Quebec.

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 IL, IN, MA, MD, ME, MI, MN, NC, NH, NY, PA, VA, VT, WI, WV
Canada MB, ON, QC

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
IN Newton (18111), Porter (18127)
MA Berkshire (25003)*, Franklin (25011)*, Hampden (25013), Middlesex (25017), Norfolk (25021)*, Plymouth (25023)*, Worcester (25027)
MD Allegany (24001), Washington (24043)
ME Kennebec (23011)*
MN Wadena (27159)
NH Cheshire (33005), Grafton (33009)*, Hillsborough (33011)*, Merrimack (33013), Rockingham (33015)
PA Centre (42027), Crawford (42039)*
VA Madison (51113)*, Page (51139)*
VT Chittenden (50007), Windham (50025)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Lower Kennebec (01030003)+*, Nashua (01070004)+, Merrimack (01070006)+, Waits (01080103)+*, West (01080107)+, Middle Connecticut (01080201)+, Westfield (01080206)+, Charles (01090001)+*, Blackstone (01090003)+*, Housatonic (01100005)+*
02 Middle Hudson (02020006)+*, Lower Susquehanna-Penns (02050301)+, North Branch Potomac (02070002)+, Cacapon-Town (02070003)+, South Fork Shenandoah (02070005)+*, Rapidan-Upper Rappahannock (02080103)+*
04 Little Calumet-Galien (04040001)+, Winooski River (04150403)+, Lamoille River (04150405)+, Lake Champlain (04150408)+
05 Shenango (05030102)+*
07 Crow Wing (07010106)+, Kankakee (07120001)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A small sedge with a sharp angled, unbranched stem, narrow leaves, and one or two sessile flowering spikes.
Technical Description: Rhizome: short with cormlike swellings. Culms: 2.0-10.0 dm tall, scabrous above on the sides and sharp angles, unbranched below the inflorescence. Leaves: basal, up to 4.0 mm wide, seldom reaching the inflorescence, smooth or scabrous on the margins. Inflorescence: 1-2 oblong, sessile spikes and 2-5 rays. Flowers: perfect, without perianth, 2 ranked in spikelets. Involucral bracts: divergently ascending or spreading. Spikes: hemispherical, 4-14 flowered. Spikelets: 5-22 mm long, not reflexed, loosely arranged in subcapitate heads, radiating from the summits of very short axis. Scales: with 11-15 well distributed nerves, round to obtuse, with a minute mucro, 2.0-2.5 mm long and 1.0-1.5 mm broad. Achenes: stout, trigonous, rounded below, nearly truncate above, 1.2-1.8 (2) mm long and 0.8-1.2 mm broad, dark brown.
Diagnostic Characteristics: Perennial, spikelets not reflexed, loosely arranged in irregular subcapitate heads, radiating from the summits of very short axes. Scales subcircular, less than 3 mm long, minutely mucronate, with 11-15 nerves. Achenes: trigonous, stout, about 2/3 as wide as long, with concave sides. Stigmas: 3.
Duration: PERENNIAL
Reproduction Comments: n=84-86.
Ecology Comments:

Cyperus houghtonii is a perennial herb, with a tough, corm-like rhizome. Virtually nothing is known about its reproductive biology, but presumably it reproduces both sexually and vegetatively.

Extensive population studies, including morphologic, cytologic and chromatographic analyses have been done, however (Marcks 1967 and 1972), and these studies indicate that Cyperus houghtonii is of backcross hybrid origin to Cyperus lupulinus ssp. macilentus, selected out of postglacially formed hybrid swarms of Cyperus lupulinus ssp. macilentus and Cyperus schweinitzii (Marcks 1974). Marcks hypothesizes that the glaciated habitat in which most populations of Cyperus houghtonii occur provided a new niche to which neither of this species' parents were well adapted, and that the new hybrid was better suited to the habitat. However, the presence of native populations of the plant outside of glaciated areas (these populations were unknown to Marcks) calls this theory into question.

The ecology of this species has not been carefully studied, but numerous published and unpublished accounts suggest that the species is adapted to, and likely dependent upon, some degree of disturbance. Judging from the habitats that are described for the plant, it appears that almost any type of disturbance of the correct magnitude will favor the plant. Fire, wind, water and downslope soil or rock movement are cited as natural disturbances that characterize the plant's habitat. Anthropogenic disturbances are equally common in some places, and in many cases apparently complement natural disturbances in providing suitable habitat for the plant. Among these are trail and road use and maintenance, railroad use and maintenance, mining and other excavation activities. Several botanists familiar with the species suggest, however, that excessive human use is likely to be detrimental to the species; only disturbances that mimic natural events such as fire, erosion and wind are likely to benefit the species.

Terrestrial Habitat(s): Sand/dune
Habitat Comments: Cyperus houghtonii ranges generally from southwest Quebec west to southeast Manitoba, and south to Virginia, Ohio and Illinois. It is known from the following provinces and states: Quebec, Ontario, Manitoba, Maine, New Hampshire, Vermont, Massachusetts, New York, Pennsylvania, Maryland, West Virginia, Virginia, North Carolina, Ohio, Indiana, Illinois, Michigan, Wisconsin and Minnesota.

Marcks (1974) described its habitat as dry exposed sands of jack pine (Pinus banksiana) barrens in glaciated eastern North America. He cites natural disturbance from wind throw and fire as providing suitable habitat for Cyperus houghtonii and its relatives. Other habitats are known for the species, but in general the habitat can be summarized as open, often sandy, dry areas which receive some disturbance, either by fire, wind, water (on shores) or human activity. In most of its range, the habitat is open sand, but in a few places it occurs in rocky habitats. In the southeastern portion of its range, for example, shale barrens are known to provide habitat for this species, and in Massachusetts, the plant occurs on trap rock escarpments. The abundance and habitat of the plant in each of the provinces and states where it occurs are summarized in the following paragraphs:

Quebec: Cyperus houghtonii is a S3 in Quebec. As of 1991 its status has not been fully evaluated. Approximately 18 stations were known, mostly from herbarium records that predate 1970 (the most recent record was 1980). The sizes of these populations were unknown. Most of the records were from the St. Lawrence and Ottawa River valleys. The habitats described on herbarium labels include sandy shorelines, sandy alluvial terraces along shores, dunes, sandy fields and railroad ballast (Hay 1991 and Labrecque 1991).

Ontario: Argus and White (1982) list Cyperus houghtonii in their Atlas of the Rare Vascular Plants of Ontario. As of 1991 approximately 23 records were known; many of these from the 1970's. The most recent record was 1982. Most of the stations were near rivers or lakes. The natural habitats described on herbarium labels include dry open sandplains, open sandy woods, alluvial sand in a blowout, dry Cladonia-Danthonia meadow, open sandhills, and sandy beaches. One collection was made from moist woods, an unusual habitat for this species. Anthropogenic habitats include an abandoned gravel pit, sandy roadsides, old fields, and waste soil near buildings (Crispin 1991). All of the Ontario specimens have been determined by P.W. Ball.

Manitoba: As of 1991 ten records were known from southeast Manitoba, only one of them recent (1986). All of the stations were found along a glacial beach ridge that runs north and south from the south end of Lake Winnipeg south. The ridge has sand, gravel and mud habitat. One of the collections was made from a sandy area, but the exact habitat of the other collections is unknown (Johnson 1991). The forest in the region is boreal: common tree species are Picea glauca, Pinus banksiana, Picea mariana and Larix laricina.

Maine: A single historical locality is known from Maine: the plant was collected in 1905, beside the Sebastocook River in southern Maine (Gawler 1981). Nothing is known of its current status. The species is ranked SH.

New Hampshire: Cyperus houghtonii is listed as S1 in New Hampshire. As of 1991 five stations were known, though only one of these was current. The habitats described were a gravelly field with the topsoil removed, an open sandy bank, a sandy disturbed roadside near a pond, and a sandy sloping dirt raod under a powerline, with Cyperus filiculmis, Cyperus strigosus, Myrica gale, and Andropogon scoparius.

Vermont: Cyperus houghtonii is considered rare in Vermont (it is ranked S2 at present. As of 1991, eleven current localities were known, as well as 5 historical ones (Marshall 1991). All of the sites were in Chittenden County, in the valley of Lake Champlain, where Vermont's only major sand deposits are found. The habitats described in both recent and historical records include open sand, sand spoil piles, sandbanks, sandy disturbed pasture, woods trails, sandpit, open gravelly sand of a testpit, pasture, and railroad crossing. Associates include Paspalum ciliatifolium, Carex muhlenbergii, Trichostema dichotomum, Leptoloma cognatum, Eragrostis spectabilis, Helianthemum canadensis, Helianthemum bicknellii, Panicum depauperatum, Quercus velutina, Pinus rigida, Cyperus filiculmis, Cenchrus longispinus, Lespedeza capitata, Panicum columbianum, Panicum xanthophysum, Panicum latifolium, Carex lucorum, Solidago puberula, Polygonella articulata, Carex umbellata, and Ammophila breviligulata (Gilman 1991, Engstrom 1991, Marshall 1991 and Countryman 1990)

Massachusetts: As of 1991 two current populations and 6 historic ones were known, and the plant is listed as S1. There is some question as to whether the historic populations were native. Both of the known populations are on open traprock escarpments, associated with red pine, and in areas that have burned in recent years. The sites are open to westerly winds and weather. Associates include Pinus resinosa, Betula lenta, Diervilla lonicera, Panicum depauperatum, Erechtites hieracifolia, and Conyza canadensis (Sorrie 1991 and 1989; Weatherbee 1991).

Rhode Island - Marcks (1974) shows a dot indicating that the plant occurs in Rhode Island, but there is no other indication that it is or ever has been known from the state (Enser 1991).

New York: Cyperus houghtonii is rare in New York, listed as S3 by the Natural Heritage Program. As of 1991 seven current localities were known, along with approximately 23 historical localities. The sites are scattered throughout the state. Most of the sites are in sandy habitats. Habitats dscribed include sandy pitch pine and oak woods, sandy roadsides, and railroad yards and tracks. A high percentage of the known sites are in anthropogenic habitats (Young 1991; Zaremba 1991).

Pennsylvania: Cyperus houghtonii is very rare in Pennsylvania. As of 1991 a single current loaclity was known, along with one other historical site. The current locality was a dry, open shale slope at 1150 feet elevation. The other collection was made on railroad ballast along a heavily used railroad line that runs from Lake Erie to Pittsburgh (Wiegman 1991 and Dix 1991).

Maryland: The species is rare in Maryland. The current rank is S1. As if 1991 there were two extant stations for the plant, although the identity of the plants at these sites is in question (Cooley 1991). A third population has been destroyed by road construction. One of the extant populations is found on dry, open sandstone talus, sandy slopes and grassy balds. The other extant population is on a shale barren. The destroyed site was on a shale barren also. Boone (1991) cites drought stress and a history of fire as important in maintaining at least one of the populations.

West Virginia: As of 1991 a single site is known from West Virginia; the plant was collected there in 1979 and misidentified (presumably as Cyperus filiculmis). Tucker (1987) identified the specimen as C. houghtonii. The rank in 2000 is S?.

Virginia: A single historical localty is known from Virginia. The site is a greenstone cliff at about 4000 feet elevation, in Page County. The site has been visited by botanists but the Cyperus houghtonii has not been relocated. Interestingly, however, the site has a number of interesting plants, northern species which are considered glacial relics at this site. Marcks (1974) suggests that the Virginia population was adventive, but Virginia botanists believe that it was a native member of a boreal relic plant community (Ludwig 1991).

North Carolina: A single site is known, from dry soils in the Piedmont. As of 2000 it is ranked SH.

Ohio: A single historical record (1895) is known from Ohio, and the species is listed as SX. The habitat of the plant is presumed to have been open sand dunes, in full sun (Cusick 1991).

Indiana: Cyperus houghtonii is listed as a S2 in Indiana. Deam (1940) lists it from two counties; Swink and Wilhelm (1979) list it from six (in each case these are in the northwestern corner of the state). It is possible (Swink and Wilhelm 1979) that the known populations are not all pure C. houghtonii; various hybrid combinations with C. filiculmis and C. schweinitzii are possible (see discussion of the possible hybrid origin of C. houghtonii in below). The Indiana specimens need careful study, and the status of the plant needs review in the state. The habitat is described as sandy soil and railroad ballast, disturbed sandy portions of prairies, savannas and foredunes (Swink and Wilhelm 1979; Hedge 1991; Pavlovic 1991). Disturbance, either by fire or winter storms with high winds, is thought to be important in maintaining habitat for this species. Associates include Ambrosia artemisiifolia, Eragrostis spectabilis, Euphorbia dentata, Froelichia gracilis, Helianthus petiolaris, Kochia scoparia, Mollugo verticillata, Polanisia graveolens, Setaria viridis, Silene cserei, Tradescantia ohiensis, Cyperus schweinitzii, Carex pensylvanica, Panicum implicatum, Panicum villossissimum, Arabis lyrata, and Krigia virginica.

Illinois: Marcks (1974) does not list Illinois as within the range of the plant. Swink and Wilhelm (1979) show it as occurring in seven counties, and Mohlenbrock (1967) lists it from six (all in northeastern Illinois). Mohlenbrock states that numerous purported collections of this plant were misidentifications, and Swink and Wilhelm suggest the problem of possible hybrid plants. Swink (1991) reiterates this position, suggesting that all Illinois plants may be applicable to a hybrid population. As of 2000 it is listed as a S2.

Michigan: Cyperus houghtonii is a S3 in Michigan. As of 1991, it was known from 18 counties (Voss 1972 and 1991); Voss has records on 70 Michigan collections of the species. The habitat (Voss 1972) is "sandy, usually disturbed places such as dunes, shores, trails and roads in jack pine, oak or aspen woodland." Reznicek (1991) describes the habitat as bare, open sand barrens with sparse tussock grasses and sedges. Both Reznicek and Voss (1991) indicate that it seems to be adapted to disturbance, including fire. Associates include Pinus banksiana, Quercus sp., Polygonella articulata, Krigia virginica, and Helianthemum canadense.

Wisconsin: This plant is not rare in Wisconsin; in fact, it may be more common in Wisconsin than in any other state or province (Marcks 1974). It inhabits a variety of semi-open to open sandy areas, including jack pine-oak barrens, sandy shorelines of river flowages, sand hill blow-outs, sandy roadsides, railroad beds, fire lanes and trails, and sandy edges of gravel and borrow pits (Dobberpuhl 1991). Dobberpuhl indicates that it occurs in disturbed areas and cites fire, fluctuating shorelines, sand blow-outs and mowing as of likely importance in maintaining its habitat.

Minnesota: Cyperus houghtonii is described a S3 in Minnesota. Scattered, small populations occur in transitional/successional habitats. Smith (1991) states that it requires a certain amount of disturbance.

Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: More information on the biology, habitat and management needs of Cyperus houghtonii are needed, but the information presented here makes it clear that in states and provinces where the species is rare, the habitat of the plant should be protected. This usually means that large areas are needed, in order to insure that natural or artificial disturbance (fire in many cases) can be maintained and the plants can survive this disturbance and recolonize. Often the habitat for this plant has other values (as a rare community or habitat for other rare plants or animals), so its protection and management will serve more than just Cyperus houghtonii.
Restoration Potential: Nothing is known about how well this species is able to recover from population decline or loss. No attempts to recover the species are known. Since the plant grows in human-influenced habitats, it is assumed that it is able to recover from a certain amount of disturbance of its habitat, but more information on this is needed.
Preserve Selection & Design Considerations: Protection of this species is appropriate in many of the states and provinces in which it occurs. Protection techniques, however, must be assessed on a case-by-case basis, depending largely upon the physical features of the habitat of the plant. See comments on management under Section 7010, below.
Management Requirements: It is very likely, considering the information on the habitat of Cyperus houghtonii, that maintenance of populations requires active management.

Cyperus houghtonii occurs in open habitats, and several controllong factors in keeping habitat open have been described above. Fire, wind, water, drought, heat and human disturbance have all been cited. Protection of populations of this plant needs to be informed by a knowledge of the long-term disturbance history of the site and the general area, and protection should not be attempted unless this disturbance history can be maintained or duplicated either naturally or artificially.

In the cases where Cyperus houghtonii grows on naturally open, exposed ledges where wind, heat and drought are important factors, then protection may be relatively easy and could involve nothing more than protecting the habitat and a suitable buffer from major human disturbance.

Where water is the major disturbance (as on lake and river shores), protection would require insuring the maintenance of the natural or preexisting regime of water level fluctuations, along with protection from major human impacts on the site itself.

Where wind is a major influence (as in some dune areas along the Great Lakes), protection could be as simple as maintaining the natural vegetation in a large enough area to insure that adequate habitat for the plant is always available.

Where fire seems to be the main determining factor in keeping habitat open, large tracts of land will be needed to maintain the communities with which Cyperus houghtonii is associated. Natural or human-induced fires will be needed to maintain the habitat.

Where human disturbance keeps habitat open by mimicing natural disturbance, every effort should be made to return the habitat to a natural disturbance regime, as by introducing fire. The appropriateness of protecting this plant in highly altered habitats should be examined on a case-by-case basis.

Monitoring Requirements: In states and provinces where Cyperus houghtonii is rare, threatened or of some concern, populations should be monitored with the following questions in mind: What is the longevity of individual plants? What is the reproductive success of the population? How does the habitat change over time? In particular, are other species encroaching to the extent of threatening the Cyperus? How is the population influenced by human intrusion? Other pertinent questions relative to the biology and life history of the species are listed below (Section 6010).

To be effective and to maximize information gained, permanent plots should be established in populations chosen for monitoring. Following is a range of procedures, from less to more labor-intensive, that could be followed: procedures used will depend upon the population and its habitat, and upon the availability of labor.

Photograph the population from several points and from different distances, keeping the location of the camera, angle of view and length of lens the same from year to year. Photography should take place at the same time each year, perhaps when plants are in fruit.

Map the vegetation in and near the population, maintaining accuracy to within 10 cm in the population and to 50 cm outside the population.

Count plants in the population each year, and record number of plants that have set fruit.

Monitor several individual plants, recording size, number of spikes and spikelets, and proximity of other plants (Cyperus houghtonii as well as other species).

Monitoring Programs: In Vermont, (as of 1991) at least one population has been montitored in compliance with a development permit (granted through Act 250, the state's land use law). The population was monitored twice in 1990, in spring and fall. The development plans have been postponed, so monitoring will probably not take place in 1991. 1990 data will be regarded as baseline data (Gilman 1991).
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: 13Mar1994
NatureServe Conservation Status Factors Author: Ormes, M. (1986), rev. L. Morse (1994)
Management Information Edition Date: 03Jun1991
Management Information Edition Author: ELIZABETH H. THOMPSON
Element Ecology & Life History Edition Date: 31Jan1992
Element Ecology & Life History Author(s): ISAAC, J.

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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  • Argus, G.W., and D.J. White, eds. 1982. Atlas of the rare vascular plants of Ontario. Part 1. National Museum Natural Science, Ottawa.

  • Argus, G.W., and K.M. Pryer. 1990. Rare vascular plants in Canada. Our natural heritage. Canadian Museum Nature, Ottawa. 191 pp. + maps.

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  • Gleason, H.A. 1952. New Britton & Brown. Illustrated Flora. Lancaster Press Inc. Lancaster, Pa. B52GLE01PAUS

  • 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.

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  • Gleason, Henry A. 1952. The New Britton and Brown Illustrated Flora of the Northeastern United States and Canada.

  • 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.

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  • Herbarium, Department of Botany, University of Manitoba, Winnipeg, Manitoba, Canada.

  • Herbarium, Museum of Man and Nature, 190 Rupert Avenue, Winnipeg, Manitoba.

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  • Manitoba Conservation Data Centre. 2018. Vascular Plant Species ranking forms from initial CDC ranking.

  • Marcks, B.G. 1974. Preliminary reports on the flora of Wisconsin. No,. 66. Cyperaceae II - Sedge Family II. The genus Cyperus - the umbrella sedges. Trans. Wisc. Acad. Sci. 62:261-284.

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  • Mohlenbrock, R.H. 1976. Illustrated flora of Illinois. Sedges: Cyperus to Scleria. Southern Illinois University Press, Carbondale, IL.

  • Mohlenbrock, R.H. 1976. The Illustrated Flora of Illinois, Sedges cyperus to scleria. Southern Illinois University Press. Carbondale Ill. B76MOH01PAUS.

  • Oldham, M.J., and W.J. Crins. 1998. Atlas of the Vascular Flora of southern Ontario. Draft 2. Natural Heritage Information Centre, Ontario Ministry of Natural Resources, Peterborough, Ontario. 378 pp.

  • RIEFNER, R.E. AND S.R. HILL. 1983. NOTES ON INFREQUENT AND THREATENED PLANTS OF MARYLAND INCLUDING NEW STATE RECORDS. CASTANEA 48:117-137.

  • RIEFNER, R.E., JR. 1981. STUDIES ON THE MARYLAND FLORA VII: ADDITION OF CYPERUS HOUGHTONII TORR. AND JUNCUS TRIFIDUS VAR. MONANTHOS (JACQ.) BLUFF & FING. TO THE STATE FLORA. PHYTOLOGIA 48: 146-150.

  • Radford, A.E., Ahles, H.E., and Bell, C.R. 1968. Manual of the Vascular Flora of the Carolinas. The Univ. of North Carolina Press. Chapel Hill, North Carolina. B68RAD01PAUS.

  • Radford, A.E., Ahles, H.E., and Bell, C.R. 1978. Manual of the Vascular Flora of the Carolinas. The Univ. of North Carolina Press. Chapel Hill, North Carolina. B78RAD01PAUS.

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