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Plant Species

of Special Concern

and

Plant Associations of

Sheridan County, Montana

Prepared for:
U.S. Fish and Wildlife Service

Prepared by:
Bonnie Heidel, Stephen V. Cooper, and Catherine Jean

September, 2000

MONTANA

Natural Heritage
Program

Plant Species of

Special Concern

and

Plant Associations of

Sheridan County, Montana

State Library Building • P.O. Box 201800 • 1515 East Sixth Avenue • Helena, MT 59620-1800 • 406-444-3009

USFWS Agreement Number 1448-60181-98-J378
Task Order Number 16

U. S. Fish and Wildlife Service
100 North Park,Suite 320
Helena, Montana 59601

This document should be cited as follows:

Heidel, B., S. V. Cooper, and C. Jean. 2000. Plant species of special concern and plant
associations of Sheridan County, Montana. Report to the U.S. Fish and Wildlife Ser-
vice. Montana Natural Heritage Program, Helena. 22 pp. plus appendices.

Acknowledgements

This report is dedicated to the memory of our
esteemed colleague, Jim Reichel, who had initiated
a biological inventory within the study area at the
time of his tragic passing.

The expertise and interest of U.S. Fish and Wildhfe
Service staff was integral to this project, which
greatly benefited by the coordination and expertise
of Mike Rabenberg. It also benefited from discus-
sions and help of the entire Medicine Lake Office.

The access permission and kindness of landowners
and leasees contacted in this study are acknowl-
edged with gratitude. Special thanks are also
extended to all who provided information on the
plant life of Sheridan County, or the county in
general, including Mike Rabenberg (USFWS),
Aldon Joyes, Doug Smith, Cherryl Wagner, Ted
Nordhagen, Monica Friedrich (NRCS) and Terry
Angvick (Extension Service).

Duane Lund (Natural Resource Information
Service) designed the shaded relief map. Cedron
Jones (Montana Natural Heritage Program) created
all other maps. Martin Miller processed plant
association and species records. John Hinshaw
scanned images and provided system support. Ryan
Rauscher prepared the climate graph. Debra
Tirmenstein computerized the plot data. Margaret
Beer professionally formatted the final report and
helped orchestrate all of the above-mentioned
work. Sue Crispin contributed expert editing. The
report also reflects the interest and technical
zoology support of Paul Hendricks. This work
benefited from the contributions of many people,
while any shortcomings rest with the authors.

This project was supported by a challenge cost-
share agreement between the U.S. Fish and Wild-
life Service and the Montana Natural Heritage
Program.

Executive Summary

Inventory was conducted in Sheridan County for
plant associations and plant species of special
concern. Forty-two plant associations are known
from the county, of which five are described for the
first time, and another nine are documented for the
first time in Montana, in addition to information
gathered on 15 undescribed types that are under
review. They include highly productive grasslands,
wet meadows, and sandhill plant associations that
are significant within Montana, and may be of
significance in the United States or the Great Plains
as a whole.

Fifteen plant species of special concern or watch
species are known from the county, of which eight
were documented for the first time, and one is
restricted to the county. Almost all of the plant
species of special concern are restricted to wet
meadow or sandy habitats. For almost half of the
15 species, Sheridan County populations represent
the largest known population in Montana. They are
rare strictly from a state perspective, though some
may be vulnerable to range wide decline.

The alkali lake systems, sandhills, and prairie
pothole mosaic of wetlands and grasslands in
Sheridan County are some of the largest identified
in eastern Montana. Range management, noxious
weed control, and related grassland/wetland
conservation measures are important to their long-
term management.

The compiled information is offered as a reference
to:

• Identify management opportunities for main-
taining rare species and high quality natural
vegetation on public lands,

• Re-evaluate plant species and natural vegeta-
tion types as they do or do not actually warrant
consideration as features of special concern,
and

• Profile biological features and areas unique to
the county for consideration in watershed
coordination and county wide planning.

This study also identified areas of high quality
vegetation and concentrations of different plant
species of special concern and plant associations.
The Missouri Coteau and the Medicine Lake areas
at the eastern end of Sheridan County have the
greatest diversity of high quality plant associations
and the highest numbers and concentrations of
special concern plant species in the county, in part
because they encompass the most extensive and
diverse wetland habitats. Upper reaches of the Big
Muddy valley and tributaries are also intact in
places and significant for their plant associations.

Table of Contents

I. Introduction 1

II. Study Area 1

B ackground 1

Climate 3

Geology and soils 3

Wildlife 7

III. Methods 7

Vegetation ecology methods 8

Botany methods 10

IV. Results 11

Overview 11

Vegetation ecology results 15

Botany results 16

V. Conclusions 18

VI. Literature cited 20

Figure 1. Sheridan County study area 2

Figure 2. Topography of Sheridan County area 5

Figure 3. Climate of Plentywood, Montana 6

Figure 4. Maximum extent of continental ice margins in the Great Plains. .6

Figure 5. Vegetation study areas in Sheridan County 9

Figure 6. Photographs of the Medicine Lake area 12

Figure 7. Photographs of the Missouri Coteau prairie pothole area 13

Figure 8. Photographs of the Big Muddy headwaters area 14

Figure 9. Plant species of special concern in Sheridan County 17

Appendix A. Animal species of special concern in Sheridan County

Appendix B . Equivalent scientific names for characteristic plants in Sheridan County

Appendix C. Plant species inventory targets in Sheridan County

Appendix D. Summary table of Sheridan County plant associations

Appendix E. Sheridan County plant associations

Appendix F. Characteristic plant associations of Sheridan County

Appendix G Range sites, ecological units, and plant associations of Sheridan

County
Appendix H. Summary table of Sheridan County plant species of special concern

and watch species
Appendix I. Sheridan County plant species of special concern and watch species
Appendix J. Flora of Sheridan County

III

Introduction

0 bjectives

The purpose of this study was to conduct a system-
atic inventory of plant species of special concern
and plant associations that represent the natural
vegetation of Sheridan County. It serves to:

• Identify management opportunities for main-
taining rare species and high quality natural
vegetation on public lands,

• Re-evaluate plant species and natural vegeta-
tion types as they do or do not actually warrant
consideration as features of special concern,
and

• Profile biological features and areas unique to
the county for consideration in watershed
coordination and county wide planning.

This study was conducted by the Montana Natural
Heritage Program (MTNHP), which collects,
maintains and provides statewide information on
features of biological significance, including
species of special concern and natural vegetation.
MTNHP serves as a clearinghouse, assembling
information from secondary sources such as
museum specimens, published articles, and reports,
and supplementing it with field studies.

Terms

This study focuses on plant "species of special
concern," which are native species that are consid-
ered vulnerable to extirpation across their range or
across the state due to inherent rarity, significant
loss of habitat, or sensitivity to human-caused
mortality or habitat disturbances. These are also
referred to as "tracked" species, since information
on their distribution and status is systematically
compiled and continuously maintained by MTNHP.
This study also addressed "watch species," which
do not currently meet the criteria described above.
These species may be in decline in Montana, or
there may simply be too little information to
accurately assess their status.

"Natural vegetation" refers to recurring associa-
tions of native plants ("plant associations") with
characteristic composition and structure and

relatively uniform environmental conditions.
Natural vegetation provides habitat for native
plants and animals, and includes the entire assem-
blage of interdependent species in a given environ-
ment. Specific forms of natural vegetation are
referred to as "plant associations". In this report,
we refer to plant associations by the names of one
or more dominant plant species.

Study Area

B ackground

Sheridan County is an area of 1,720 square miles in
the extreme northeast comer of Montana
(Figure 1). It was originally part of Big Horn
County in 1864, successively split off into smaller
counties as part of Dawson County in 1889, Valley
County in 1893, and finally Sheridan County with
Plenty wood as the county seat in 1913 (Aasheim
1970). Big cattle company operations were in
place before farming, and "Northeastern Montana
was not merely the cowman' s last frontier, it was
his paradise" (Aasheim 1970).

When the Great Northern Railroad was constructed
along the Missouri River in 1887 to connect
Minneapolis to Helena, special transportation rates
were offered to prospective settlers seeking quarter-
sections of land to farm under the Homestead Act.
A second major flurry of homesteading took place
with the construction of a Great Northern branch
line directly to Plentywood in 1910, about the time
that an amendment to the original Homestead Act
was made in 1909 to allow two quarter sections of
land per homesteader for settlement. Barely 60
years later in 1971, over half of the total acreage in
the county was dedicated to small grain production
(Richardson and Hanson 1977). The county's
greatest natural resource is its soil (Richardson and
Hanson 1977) and an agricultural landscape
prevails over much of Sheridan County today.

Against this backdrop of an agricultural landscape,
we focused this study on three areas with the least
extensive cropland. These areas coincide with some
distinguishing landscape features that are described
in the following text and represented in a map
showing the topography of the Sheridan County
area (Figure 2).

Figure 1. Sheridan County study area

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Sheridan County Boundary

Federal Lands

State Lands

Tribal & Allotted Lands

Lakes & Reservoirs

Focus Areas Mentioned in Report

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Scale in Miles

April 11,2000

Big M uddy headwaters

Big Muddy Creek traverses Sheridan County,
flowing southward into the Missouri River. The
headwaters area includes segments that have
continuous unplowed valleybottoms, slopes, and
surrounding uplands. As the largest watercourse
and valley in the county, it is a key landscape
feature and provides connectivity for both wildlife
and plants. The headwaters are located within the
northwestern part of the county (Figure 1), and the
headwaters extend into Saskatchewan.

Medicine Lake area

Medicine Lake National Wildlife Refuge (NWR)
contains the largest lake in the county. Wind has
moved sand from the lakebed to create large
sandplains to the southeast of Medicine Lake,
bordered on the north and east by Sand Creek.
They are some of the most extensive wind-borne
sand deposits in eastern Montana (from Ross et al.
1955), with topography and substrate that distin-
guish them from the rest of the county. Lake Creek
feeds into Medicine Lake, connecting it with
extensive wet meadows and other wetlands up-
stream. It is located within the southeastern part of
the county, including and east of Medicine Lake
NWR (Figure 1).

M issouri Coteau prairie potholes

The Missouri Coteau is a rolling physiographic
region that cuts a diagonal swath across the north-
eastern corner of Sheridan County (Figure 1). The
Missouri Coteau Region generally has a high
density of wetlands, with a tremendous range of
size, depth, and alkalinity. These wetlands are
collectively called "prairie potholes" in reference
to the plains setting and rolling topography. This is
the only part of Sheridan County without surface
connection to the Big Muddy watershed, instead
being made up of a series of small, closed-basin
watersheds with limited development of water-
courses.

Climate

Sheridan County has a continental climate with
cold winters, warm summers, and peak rainfall
early in the growing season. Rainfall patterns
throughout the county are those typically condu-
cive to agriculture, where precipitation is in excess
of evapotranspiration (Figure 3). The growing

season is usually 1 10-125 days long, with roughly
80% of annual precipitation concentrated during
that period. Annual precipitation ranges from 12-13
inches annually over the northwestern part of the
county to 14-15 inches over the southeastern part.
Steady, gentle rains usually occur in May, June and
September, with the rest of growing season rainfall
arriving in thundershowers (Richardson and
Hanson 1977). It lies in the Eastern Glaciated
Plains, 10-14" zone, as used to characterize state
range sites (Ross and Hunter 1976).

As is typical of continental climates, precipitation
varies greatly from year to year. For example, in
Redstone, MT, one year in ten will have a total
annual precipitation of less than 8.0 inches or more
than 18.0 inches (1954-1970; Richardson and
Hanson 1977). Similarly, Medicine Lake shows one
in ten years with total annual precipitation of less
than 9.5 inches or more than 19.1 inches (1941-
1970; Richardson and Hanson 1977).

Average daily minimum temperatures in Redstone
and Medicine Lake are at -5 degrees F in January
and average daily maximum temperatures at 85
degrees F in July. However, even these figures
mask the extremes — Medicine Lake holds the
state record for the highest temperature on record at
117 degrees F. To the casual observer, daily tem-
perature extremes may be the most noticeable.

Annual precipitation in 1998-99 when this work
was conducted was close to the mean and generally
favorable for the field study. In Redstone, the total
for 1998 and 1999 was 16.62 in. and 12.66 in.,
respectively (NO A A). In Medicine Lake, the total
for 1998 and 1999 was 14.68 and 13.4 in., respec-
tively (NO A A).

Geology and Soils

The plains landscape of Sheridan County has a
modest elevation range of 1,933-2,600 ft
(Richardson and Hanson 1977) that belies a
dramatic glacial history of repeated advances that
forced the Missouri River out of the Hudson Bay
watershed. The glacial deposits and topography
dictate over soil characteristics, which are dis-
cussed in tandem for the three study areas.

Big M uddy headwaters

One of the most pronounced landforms in the
county is the Big Muddy Creek channel, a valley
that is one to three miles wide, and originally 300 ft
deep in places, partially filled with outwash and
alluvium (Figure 2; Witkind 1959). It contains the
Big Muddy Creek, a perennial stream that is no
more than 10 feet wide in most places, and repre-
sents the largest watercourse in the county. The
north end of the Big Muddy valley and major
tributaries make up the Big Muddy headwaters,
where there are some of the largest areas of
unplowed valley and adjoining uplands.

This broad valley, which is oversized for the stream
now occupying it, is a major outwash channel
formed near the margin of a glacial front over
12,000 years ago (Clayton et al. 1980). It has
valleybottom deposits over 100 feet deep in places,
including alluvial clay and outwash (Witkind
1959). The valley is bordered by terraces that are
both pre-glacial and post-glacial in origin. In its
northern reaches, it cuts through Fort Union
Formation bedrock, variously made up of
claystone, calcareous siltstone, and sandstone. Its
headwaters and tributaries also cut into Flaxville
gravel that top the Fort Union Formation in places.

Soils in the Big Muddy headwaters area are mainly
well-drained silty clay loams and clay loams
(Lambert-Zahill association) on the valley breaks
and uplands. The valleybottoms are mainly well-
drained silt loams and silty clay loams (Havrelon-
Cherry association) on floodplains and fans
(Richardson and Hanson 1977). The fine-textured
soils and the steep topography along the valley
signify distinctly more arid conditions despite
modest differences in average precipitation in
comparing this area with the following areas.

Medicine Lake area

Another pronounced landform in the county is
Medicine Lake, a large, shallow lake that fills an
ancient valley. Medicine Lake, the adjoining
sandhills, and contiguous valley of Lake Creek are
centered along the other large glacial outwash
channel in Sheridan County, the Dagmar outwash
channel. This channel is broader than the Big
Muddy Creek channel but nearly filled with
outwash and alluvium (Figure 2). Part of its course
may have been the pre-glacial valley of the Mis-

souri River Valley (Witkind 1959). As a glacial
meltwater channel, it was an arteriole of glacial
run-off. Associated with Medicine Lake are large
sand deposits that originate from the bed of the
outwash channel. Most of the sand deposits are a
thin veneer over till and bedrock. The dunes and
gently rolling plains around them make up the
Medicine Lake sandplains. In places, they have
been reworked by the wind into small ridge sys-
tems parallel with the prevailing winds, forming
choppy dunes.

Running northeast/southwest from Medicine Lake
is Lake Creek, occupying what is thought to be a
pre-glacial route of the Missouri River, now filled
with outwash so that the wide valley is not very
deep. Water levels were modified by a spillgate on
the Lake, and a series of dikes above it that created
shallow impoundments in the valley.

Most soils in the Medicine Lake area are well-
drained to excessively drained soils on uplands,
varying in sand or gravel content and drainage.
They include the Blanchard association throughout
the sandhills, composed of well-drained and
droughty fine sands and loamy sands, and the
Lihen-Parshall association throughout the gentle
sandplains, composed of well-drained loamy fine
sands and fine sandy loams. The broad Dagmar
channel immediately northeast (upstream) from
Medicine Lake has the contrasting McKenzie
association, composed of poorly drained silty clay
loams across the lowlands.

■Missouri Coteau prairie potholes

The outwash terrain around Westby and the col-
lapsed moraine landscape around Comertown make
up the Missouri Coteau prairie potholes area, with
its high density and diversity of wetlands. The
associated topography does not show up at the
scale of the topographic map in Figure 2, except for
the largest alkali lakes. But it represents the most
complex and irregular topography in the county.
This area experienced at least three episodes of
glacial advances, indicated by maximum ice-
margin positions (Figure 4). The most recent
entered the northeastern corner of the county, and
left hummocky collapsed glacial sediment fringed
by outwash channels.

Figure 2. Topography of Sheridan County area

Figure 3. Climate of Plenty wood, MT. Diagram showing average monthly temperature and precipitation.
Growing season length is the number of frost-free days, i.e., with mean daily minimum above 0 degrees C.

3
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Plentywood, MT (625 m/2040 ft) (5.7 C/42.2 F) (332 mm/13.1 in) (1948 -1999)

Temperature
Precipitation

Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Figure 4. Maximum extent of continental ice margins in the Great Plains

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Hummocky topography is thought to result from
lateral slumping and sliding of the sediment that
overlies the glacier as it melts and collapses in
place (from Clayton et al. 1980), sometimes
referred to as "dead-ice moraine" (Kantrud et al.
1989). Steep hummocky terrain is a characteristic
feature in the Comertown area, producing wetland
basins of all sizes and shapes and high wetland
densities. Glacial outwash was deposited on
stagnant ice, and the overlying sand and gravel
slumped to form irregularly hilly terrain with many
wetlands, often including large, shallow, saline
lakes. Outwash channels around Westby are
comprised of bedded glacial sediments that lie in
topographic low points in closed-basin watersheds.
They form some of the most extensive alkali lake
systems in the state and act like large evaporation
ponds where salts accumulate.

A great variety of soil textures are reflected in these
glacial deposits. Tills in moraines are generally
silty and clayey materials that are not very perme-
able, while outwash deposits also include sand and
gravel layers (Kantrud et al. 1989). Soils over
much of the moraine deposits are mapped as Zahill-
Williams-Dimmick association. Clay loams and
loams prevail in the first two series (slopes 15-
45%). The Dimmick association is made up of
poorly-drained silty clays in wetland basins.

Wildlife

The most popular game animals of the county
include white-tailed deer, waterfowl, grouse,
partridge, and pheasant, as highlighted in the
county soil survey (Richardson and Hanson 1977).
The full array of wildlife resources of Sheridan
County are best-documented in Medicine Lake
NWR. The refuge was established in 1934 in
recognition of its outstanding waterfowl nesting
habitat for Canada geese and ducks. It has since
been recognized for its value for colonial nesting
birds, for migratory waterfowl, and as habitat for
upland grassland birds, including passerines and
upland game birds. It has been the center of activity
for most wildlife studies in Sheridan County and
adjoining areas.

In addition, there are animal species of special
concern or watch species known from breeding
records in the county (Appendix A), including
species of birds, reptiles, an amphibian, and

insects. Most of them are birds, and most of these
occupy wetlands or lakes. The ones that are depen-
dent on open water are restricted to Medicine Lake
NWR. Only the Piping Plover (Charadrius
melodus) is federally listed as threatened. Sheridan
County has the largest numbers of Piping Plovers
in Montana, and a relative abundance of grassland
birds, some of which are in decline elsewhere over
much of their range.

M ethods

0 verview

The purpose of this systematic inventory was to
identify those native plant species and plant
associations that are the least common in the state
or throughout their range, as well as high quality
examples of more common plant associations. We
began by compiling and reviewing available data in
the county and adjacent counties, states, and
provinces. We then conducted targeted field
surveys to fill information gaps for plant species
and plant association types.

Field surveys for plants and plant associations were
conducted in the summers of 1998 and 1999. The
first year was aimed at developing a list of plant
species of special concern and starting to document
the plant associations that were known or suspected
from the county. We also evaluated the distribution
and rarity of species and plant associations, to
prioritize them for further survey work.

The second year was aimed at more thoroughly
documenting priority species and plant associa-
tions, focusing on areas of relatively intact vegeta-
tion. Areas of relatively unbroken landscape and
localized vegetation features were identified using
color infrared aerial photos (NWI; 1:65,000; taken
in 1983). We transcribed notes onto U.S.G.S.
topographic maps (7.5') that were carried in the
field. In the case of some areas with complex
patterns, copies of black-and-white aerial photos
(8"=1 mile) were ordered from the USD A Farm
Service Agency for use in fieldwork. The soils
information in the county soils survey (Richardson
and Hanson 1977) was also used for reference in

the field. We obtained a great deal of valuable
information by talking with people familiar with
the county's species and landscapes.

Our principle floristic references were the Great
Plains Flora Association (1977, 1986), Dorn
(1984), and Hitchcock and Cronquist (1973).
Looman (1982) was consulted to the extent that
vegetative grass identification was needed. Nomen-
clature used in this report is generally consistent
with these references, except for revisionary
taxonomic treatments, mainly for grasses (Kartesz
1994). This means incorporating unfamiliar-
sounding names for some dominant and indicator
species, particularly the wheatgrasses (Agropyron
and Elymus in the traditional sense). Thus, western
wheatgrass, called Agro/Jjron smithii in Booth
(1950) and Elymus smithii in Dorn (1984), is
referred here as Pascopyrum smithii. Synonymous
names for the plant species of concern are cross-
referenced with the information on each species.
Synonymous names of dominant and indicator
plants are cross-referenced in Appendix B. We
have also cross-referenced each species by both
scientific name and common name the first time the
species is mentioned under each heading. Common
names are based mainly on the list developed by
the U.S. Forest Service of Region 1, generally
consistent with major floras.

Records for all populations of plant species of
special concern and for the best examples of plant
associations were transcribed from field forms onto
standardized forms, geo-referenced, and incorpo-
rated into the Heritage databases as representing
noteworthy occurrences of biological diversity.

Vegetation ecology
methods

The first year of vegetation survey took into
account the range of environmental conditions; our
survey spanned the diversity of "habitat extremes"
in order to chronicle the range of natural vegetation
in the county. In addition to photointerpretation
results, we were aided by experts who identified
unusual or specific habitats worthy of investiga-
tion. These features were concentrated in the
Medicine Lake area, Missouri Coteau prairie
potholes area, and the Upper Big Muddy area.

First year survey results were compared against our
list of known Montana plant associations to iden-
tify new discoveries or uncommon plant associa-
tions. Based on the findings, we designed the
second year of vegetation sampling to characterize:

• Well-developed examples of common plant
associations in outstanding condition;

• Plant associations of potential statewide or
range wide rarity and significance;

• Provisional new plant associations or ones
not previously known from northeastern Mon-
tana.

Plant associations were documented in terms of
their plant species composition, structure and
associated abiotic environmental conditions in 1 17
ecology plots (Figure 5), eight of which were
previously sampled at Medicine Lake NWR
(Cooper and Heidel 1999). We included three plots
outside the county but within a mile's distance and
useful in describing county features. To document
species composition, we sampled vegetation in the
representative 1/10 acre plots (37.2 ft radius or
equivalent). Ecology plots were placed to represent
homogeneous natural vegetation and uniform
environmental conditions across the plot, and the
least disturbance. Canopy cover values for all
species present, plot location and environment
characteristics were recorded on a survey form that
was later computerized for analysis and permanent
data storage. After each plot was subjectively
assigned to a plant association, average plant cover
and constancy by plant association type was
calculated using Eco analysis (V.9.12.2) computer
software. The results were used to describe plant
associations of Sheridan County.

Vegetation sampling focused on herbaceous
grassland plant associations at the outset because
grasslands are the prevailing vegetation of the
county, representing well over 90% of the existing
natural vegetation. After the first year, it also
became apparent that they are among the distin-
guishing vegetation features as well. Also after the
first year, we compared wetland observations with
wetland classification information in Montana
(e.g., Hansen et al. 1995). It became apparent that
there were many wetland plant associations present
in the county that have not been documented in the

Figure 5. Vegetation study areas in Sheridan County

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Scate in Mites

state. Wetlands are also distinguishing ecological
features of the county. We used the wetland vegeta-
tion work conducted elsewhere in the Missouri
Coteau region by the Northern Prairie Biological
Research Station (Stewart and Kantrud 1971, 1972,
and Kantrud et al. 1989) to start documenting
wetland plant associations that are "new" to
Montana.

Vegetation classification followed the National
Vegetation Classification System (NVCS;
(Grossman et al. 1998), a system that:

• Is defined in terms of recurring vegetation
attributes;

• Emphasizes natural existing conditions;

• Uses a classification hierarchy based on
structure and floristic composition;

• Can identify vegetation units based on both
quantitative and in some cases qualitative data.

The NCVS classification is hierarchical and
combines floristics at the lowest levels (associa-
tions and alliances) and structure (physiognomy)
and overarching climate conditions at the highest
levels. The plant association is defined in terms of
the dominant species of the uppermost vegetation
layer, and any co-dominant species, diagnostic
species, or the dominant species of shorter vegeta-
tion layers. Literature review and stand data

analysis had been conducted in Montana to pro-
duce an initial working list of the plant associations
in the state.

Prior to this study, the natural vegetation of
Sheridan County and northeastern Montana was
represented by scattered references. Range sites of
Sheridan County are described in the soil survey
(Richardson and Hanson 1977) and provide a
forage-production perspective on the most common
grassland vegetation. More detailed vegetation
descriptions were available for the Medicine Lake
Sandhills, and to a lesser degree in the Comertown
Prairie (Lesica 1987a, 1987b, respectively). In
1990, vegetation plots were sampled near but not
within Sheridan County in a vegetation study of
northeastern Montana (DeVelice et al. 1995). In
1997, vegetation was sampled at several sites in
Medicine Lake National Wildlife Refuge (NWR) in
a study of Research Natural Areas that included
vegetation ecology and botany (Cooper and Heidel
1999). Apart from these sources, most pertinent
vegetation information was from studies in adjoin-
ing counties, states and provinces and from the
recently compiled state and regional NVCS classi-
fications representing Great Plains states (Reid et
al. 1999, Faber-Langendoen 1999). We have drawn
on those references to provide background informa-
tion, to help build a broad picture of vegetation
diversity in the county, and to refine the working
list of plant associations in the state. The literature
that was reviewed to describe each of the Sheridan
County plant associations in the appendix is
incorporated in the Literature Cited section at the
end of the report.

Such a classification approach offers a refinement
of the sweeping generalizations that have com-
monly been used in characterizing Great Plains
vegetation as indicated by grass height (tallgrass,
mixed-grass, short-grass). Even though environ-
mental modifiers have been used with this system
to characterize "ecological sites," or "natural
communities" (e.g., Heidel 1992), such an ap-
proach has only limited consistency within state
boundaries, and quickly loses cohesion over the
expanse of North American mid-continental
grasslands as the most extensive formation on the
continent.

Botany methods

Prior to conducting fieldwork, we prepared a
"search list" of species and their habitats to use as a
reference in planning and conducting field surveys
(Appendix C). It represented those Montana plant
species of special concern previously documented
from the county or from adjoining counties,
consistent with the most current species of Mon-
tana special concern list (Heidel 1999). It also
included native plant species not known from
Montana but occurring in nearby areas of North
Dakota and Saskatchewan that may have suitable
habitat in Montana. Information on the phenology,
habitat needs, and known distribution of these
target plant species was assembled from Natural
Heritage Program databases, published and unpub-
lished literature, and species checklists from
adjoining states and provinces.

Aerial photographs, USGS topographic maps,
geologic maps, and soil survey maps were con-
sulted to identify areas of potential habitat for
ground survey. We targeted previous records of
plant species for re-visit if there were questions on
the species' location, setting, or population num-
bers. Botany fieldwork was conducted mainly in
the second year of study, often in tandem with
vegetation ecology work.

During fieldwork, data were collected on the
biology, habitat, population size, and any indica-
tions of trend for the target species. Locations of
target species were mapped onto U.S.G.S. topo-
graphic maps (7.5'). Information gathered in the
field was entered into the MTNHP data system, and
mapped locations were digitized if the population
extended beyond a single place on the landscape.
Voucher specimens were collected if population
numbers were sufficiently large to avoid impact
(Montana Native Plant Society 1993).

Previous collection records of the plant species of
special concern in Sheridan County have already
been compiled in the MTNHP database from the
major herbaria of the state and most major herbaria
of the region, as well as from the literature. For
other questions of species distribution, as in the
case of watch species, we used two references with
county dot maps (Booth 1966, Great Plains Flora
Association 1977), the general descriptions of state
distribution that are in Dom (1984), and prehmi-

nary checklists in unpublished reports. We also
reviewed a set of plant specimens collected on
Medicine Lake NWR for any collections of plant
species of special concern, and as habitat indica-
tors. We maintained a running list of the vascular
flora over the course of the field surveys, and
collected species that could not be positively
identified in the field for later determination.
Specimens will be deposited at the University of
Montana (MONTU).

We reviewed current plant taxonomy literature and
other sources of information in making determina-
tions and assembling the most current status
information on each of the species and evaluating it
in light of study results. The literature review for
each of the plant species that are described in the
appendix is incorporated in the Literature Cited
Section at the end of this report.

Results

Overview

This study identified 42 plant associations and 12
plant species of special concern plus three watch
species in Sheridan County. Five of the plant
associations are newly-described types, and nine
more are new to the state. They include highly
productive grasslands, wet meadows, and sandhill
plant associations. These are particularly signifi-
cant as the only and best of known examples within
Montana, and may be of significance in the United
States or the Great Plains as a whole.

Eight of the fifteen plant species of special concern
were documented in Sheridan County for the first
time. Results significantly expand their known state
distribution. Only Sisyrinchium septentrionale
(northern blue-eyed grass) is known in Montana
only from Sheridan County. Three of the 15 species
were not successfully relocated but survey work
was not adequate for saying that they are no longer
present.

Results of the vegetation ecology and botany work
are highlighted in this section. They are detailed in
tables and text that are in the appendix with de-
scriptions of each plant associations and plant

species identified in this study. The descriptions
include a summary of their distinguishing charac-
teristics, habitat, status, state and county distribu-
tion, and management considerations.

The eastern end of the county supports the greatest
diversity of native vegetation types and significant
plant species, in part because it has the most
extensive and diverse wetland habitats. These are
concentrated in the Medicine Lakes area and the
Missouri Coteau prairie potholes region. Another
diverse area with good ecological diversity and a
number of significant species is the Big Muddy
Creek headwaters. The biological diversity and
significance of these three study areas is summa-
rized below.

Medicine Lake area

The Medicine Lake area has the most extensive
open water habitat in the county. Medicine Lake is
the largest lake in the county, and Brush Lake is the
deepest lake in the county, both lying along the
Dagmar outwash channel. Medicine Lake is the
defining feature of Medicine Lake NWR, estab-
hshed in 1934 for its high value in providing
nesting habitat for waterfowl. Water bodies near
Medicine Lake and Brush Lake support Piping
Plovers (Charadrius melodus), a threatened shore-
bird. Brush Lake has also provided insight in to the
ecological history of the area through research on
its uninterrupted sediment records (e.g.,
Umbanhowar 1996).

The Medicine Lake NWR has already been docu-
mented as harboring seven bird species of special
concern that require open water, some of them
occurring nowhere else in the county. They include
American White Pelican (Pelecanus
erythwrhynchos). Black Tern (Chlidonias niger).
Black-crowned Night-heron (Nycticorax
nycticorax), Caspian Tern {Sterna caspia).
Forester's Tern {Sterna f or steri), Franklin's Gull
{Larus pipixcan), and Great Blue Heron {Ardea
herodias). Altogether, this area supports at least 15
Montana animal species of special concern, includ-
ing the Ottoe Skipper {Hesperia ottoe), a butterfly
which usually feeds on the nectar of purple cone-
flower {Echinacea angustifolia).

Figure 6. Photographs of the Medicine Lake area

The Medicine Lake sandiiills aie among the largest sand deposits in eastern
Montana, with intact uplands made up of the needle-and-thread - lemon
scurfpea plant association.

Choppy sand dunes and associated blowouts are uncommon in the
sandhills, and three of the plant species of special concern are
concentrated in these small, scattered areas, including Schweinitz'
flatsedge (lower right).

Medicine Lake is the largest lake in the county, with major waterfowl and
shorebird values, and use by seven bird species of special concern that
require open water.

Peatland communities made up of parallel bands of
"chalky" marl pools and mounds are uncommon along
outwash channels, including Lake Creek.

Figure 7. Photographs of the Missouri Coteau prairie pothole area

Closed-basin alkali lakes provide some of the most significant piping
plover breeding habitat in the state.

Pale-spike lobelia is among four Montana plant species of
special concern that are in prairie pothole landscapes and
restricted to wetland margins.

The rolling prairie pothole topography encompasses a mosaic of grassland and wetland plant
associations, including the northern porcupine grass plant association (left of wetland), with
its rich forb and shrub component that turns north-facing hillsides into swaths of early-
summer color.

Figure 8. Photographs of the Big Muddy headwaters area

Intact valley bottom segments and bordering
tablelands distinguish the Big Muddy
headwaters area.

Valley segments with intact spring-fed wetlands and woodlands are even less
common than the typically dry, open valley settings along the Big Muddy and
its tributaries.

Also present are remnants of some of the more
extensive wet meadows in the county in widely-
scattered pockets. One of the wet meadow types,
the Panicum virgatum - Muhlenbergia
richardsonis - (Schizachyrium scoparium) plant
association, is newly-described. This once-wide-
spread community is reduced to small tracts. Small,
isolated pockets of peatland that were never
extensive are also found in the area.

The nearby sandplains are among the largest wind-
borne sand deposits in eastern Montana judging by
the geologic map of the state (Ross et al. 1955).
They harbor five plant species of special concern,
at least three of which have their highest known
numbers for the state in this area where they are
scattered across the landscape, including
Schweinitz' flatsedge {Cyperus schweinitzii),
Fendler cat's-eye {Cryptantha fendleri), and plains
phlox {Phlox andicola). One of the sandhill vegeta-
tion types, the Stipa comata - Psoralidium
lanceolatum plant association, is described here for
the first time, corroborating reports in earlier work
by Lesica (1987a). A composite view of distin-
guishing Medicine Lake area features is presented
in Figure 6.

Missouri Coteau prairie potholes

The rolling Missouri Coteau prairie pothole terrain
contains the highest diversity of plant associations,
highest densities of wetlands, and some of the
largest unbroken prairie landscapes in the county
(Figure 6). This rich mosaic of grassland and
wetland associations is part of the North American
Prairie Pothole Region, a region that supports 50%
of continent's annual duck production in an average
year though it covers an area that is only 10% of
the net waterfowl breeding area (Smith et al. 1964;
in Kantrud et al. 1989).

Five Montana wetland plant species of special
concern have been found here. Four occupy the
dynamic, vulnerable wetland perimeter, including
many-headed sedge (Carex sychnocephala),
chaffweed {Centunculus minimus), pale-spike
lobelia {Lobelia spicata) and northern blue-eyed
grass (Sisyrinchium septentrionale). Three of the
grassland plant associations are "newly-described,"
based on vegetation sampling data, review, and
synthesis of the literature; also corroborating a
report of the Elymus lanceolatus - Stipa comata
plant association by Lesica (1987b). All nine of the
wetland plant associations that are new to Montana

are in this area, and most of them were not found
outside of it.

Closed-basin alkali lakes are best-developed and
most extensive in this area, with specialized stress-
tolerant plant associations and some of the most
significant Piping Plover (Charadrius melodus)
breeding habitat in the state. Other wetland bird
species of special concern are also known from this
habitat, or the springs and seeps feeding into them.
In our sampling, the alkali lake systems had the
highest concentration of plant associations that did
not correspond with any of those documented in
existing vegetation classification literature, includ-
ing both upland and wetland associations domi-
nated by species of wheatgrass. A composite view
of distinguishing Missouri Coteau prairie pothole
features is presented in Figure 7.

Big M uddy headwaters

The Big Muddy headwaters bring together species
of the Canadian Parklands, Great Plains, and the
American Southwest, in its intact bottomlands and
adjoining tablelands. It includes areas of well-
developed Badlands and spring-fed tributaries. The
results are a biogeographic melting pot of sorts,
although there are few species of special concern
here. Two woodland plant species that are on the
state watch list, lavender hyssop (Agastache
foeniculaceum) and common agrimony (Agrimonia
gryposepala), were found in or near this area for
the first time in the county in the course of the
study.

The Big Muddy Creek in and below the headwaters
area is a low-gradient perennial stream. It traverses
the county in an open-water corridor, providing a
landscape link between the Medicine Lake area and
the Big Muddy headwaters. It supports a produc-
tive submergent plant association that includes
sago pondweed (Potamogeton pectinatus), com-
mon watermilfoil (Myriophyllum spicatum), and
homed pondweed (Zannichellia palustris). A
composite view of distinguishing Big Muddy
headwaters features is presented in Figure 8.

Other areas

Below the headwaters, a number of tributary
valleys and side coulees along the west side of the
Big Muddy valley support luxuriant spring-fed
coulees, intact but dry bottoms in outstanding

condition, and cool, shady ravine woodlands. Even
higher in the uplands, escarpments rise to the
southwest, and their most sheltered slopes contain
the largest woodlands in the County, outlying
habitats that greatly contribute to plant and animal
diversity. In places, the Green Ash Woodland gives
way to sheltered pockets of Aspen Woodland.

Vegetation Ecology Results

We identified a total of forty-two plant associations
in Sheridan County through field survey. This
includes five that are described and documented as
plant associations for the first time, and nine that
were not previously known from Montana, though
they had been previously described elsewhere
(Appendix D, Appendix E). The large number of
plant associations identified as new to Montana
point to the paucity of vegetation information that
has been available for eastern Montana in general
and the Missouri Coteau in particular.

The five newly-documented plant associations are
all grassland types. Three of these are dominated
by species not widely recognized as forming
discrete plant alliances in the United States,
including thick- spike wheatgrass (Elymus
lanceolatus) and northern porcupinegrass (Stipa
curtiseta). These are northern species of wheat-
grass and needlegrass that are more common in
Canada than they are in the U.S., and are not
poorly-represented in the vegetation ecology
hterature of the United States. Major Canadian
references on vegetation have not been completely
integrated into plant association classification, and
for this study, we have simply confirmed the
presence or variants of these types in Montana,
cross-referencing them to the Canadian literature.
The three "newly-documented" plant associations
of the northern plains include:

• Elymus lanceolatus - Stipa comata Herbaceous
Vegetation

• Elymus lanceolatus - (Koeleria macrantha)
Herbaceous Vegetation

• Stipa curtiseta Herbaceous Vegetation

The other newly-described associations are more
characteristic of the plains to the east:

• Panicum virgatum - Muhlenbergia
richardsonis - (Schizachyrium scoparium)
Herbaceous Vegetation

• Stipa comata - Psoralidium lanceolatum
Herbaceous Vegetation

A series of schematic landscape cross-sections
shows the placement of the most characteristic
grassland plant associations in the three study areas
(Appendix F). We have also developed a prelimi-
nary cross-reference between the range sites and
the plant associations to help relate our results to
soil survey data and range management literature
(Appendix G). These were created after fieldwork
when it became apparent that so many of the plant
associations were not recognized in existing
compiled classifications.

Most of the plant associations identified as new to
Montana are wetland types. Wetland classification
work conducted in the Missouri Coteau outside
Montana generally applies in Sheridan County
(e.g., Kantrud et al. 1989, Stewart and Kantrud
1972), which characterizes the vegetation for all of
the common prairie pothole wetland settings in
Sheridan County. One of the more unusual and
intrinsically rare wetlands is the few-flowered
spike-rush (Eleocharis quinqueflora) marl fen, a
patterned rich fen representing a form of alkaline
peatland, otherwise only reported from North and
South Dakota. It occurred not only in the "string-
and-flark" peatland patterning that has been
reported for related peatlands in European litera-
ture, but in bands formed in concentric circles
around springheads in patterns suggesting dome-
building accretion and collapse.

We ran vegetation analysis on 117 vegetation
sampling plots (including 8 plots from earlier
work). Of the 57 plant associations, only 11 are
documented by four or more vegetation sampling
plots, including most of the types which are newly-
described or new to Montana. The sample size for
our characterizations is limited.

Appendix E includes descriptions of all the plant
associations we identified. Those described in
greatest detail are newly-documented types, types
documented for the first time in Montana, or types
occurring extensively in the county. They are
organized into the groups presented in Table 2,

with the exception that wetland types have been
grouped separately from grassland types rather than
combined under "herbaceous vegetation." We
present grassland types first as the predominant
vegetation of the county.

Fifteen of the fifty-seven plant associations that we
sampled in this study were noted from no more
than two plots or observations, and they do not
correspond to plant associations described for
immediately adjoining areas of the Great Plains.
Most of these are localized features, and many are
associated with alkali lake systems. They warrant
expanded field investigation and further consulta-
tion with vegetation ecologists in Saskatchewan,
Alberta, and North Dakota. They are listed at the
end of Table 2 as undescribed types, and treated at
the end of the grassland, wetland, shrubland, and
woodland sets in Appendix E.

Botany Results

This study identified twelve Montana plant species
of special concern documented for the county and
three that are on the state watch list (Appendix H,
Appendix I). Seven of the species are restricted to
wetlands of the Missouri Coteau and Medicine
Lake areas, and five are restricted to sandhills of
the Medicine Lake area (Figure 9). They reflect
requirements for some of the habitats that are
particularly well-developed in the county, namely
wetlands and sandplains. It is important to note that
most of the species are at the western margins of
their distribution and are widespread elsewhere.
Some may be vulnerable to range wide decline.
Most of them are known from few places in the
county, though they may be locally common at
those sites. These species are key parts of county
biological diversity.

About half of these fifteen species were docu-
mented for the first time in Sheridan County in the
course of this study, though none are new to the
state flora.

The five plant species of special concern that are
newly documented in the county include:

• Chaffweed (Centunculus minimus)

• Mealy primrose (Primula incana)

• Ovalleaf milkweed (Asclepias ovalifolia)

• Silky prairieclover (Dalea villosa var. villosa)

• Smooth goosefoot (Chenopodium subglabrum)

Figure 9. Plant species of special concern in Sheridan County

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The three watch list plants species newly docu-
mented in the county are:

• Common agrimony (Agrimonia gryposepala)

• Kalm' s lobelia {Lobelia kalmii)

• Lavender hyssop (Agastache foeniculaceum)

Hairy four o' clock {Mirabilis hirsuta), was re-
cently dropped from the Montana plant species of
special concern list because we found it in a broad
range of natural and disturbed habitats, occurring
repeatedly in the Medicine Lake area (Cooper and
Heidel 1999). It is possible that some species like
plains phlox (Phlox andicola) are much more
widespread in native grasslands of the Medicine
Lake sandplains than previously known, however

we were unable to survey their habitats extensively
at the right times to make such a determination.

One other species that had been recommended for
addition to the state watch list has been dropped
from consideration based on this study. We found
rush aster (Aster junciformis) to be present in the
various peatland habitats of the county, and com-
mon in many of them. It has a distribution in
Montana much like Kalm's lobelia (Lobelia
kalmii), in the northwest and northeast corners, but
is known from more stations and a much wider
range of habitats.

Two wetland plant species of special concern that
were historically known from the Medicine Lake

NWR were sought and not found. They are pale-
spike lobelia (Lobelia spicata), which we did find
on the Missouri Coteau, and slender bulrush
(Scirpus heterochaetus). Neither did we
relocate many-headed sedge (Carex
sychnocephala) near Comertown, a wetland plant
which had been collected little more than a decade
ago, or have the correct location information to
search for northern blue-eyed-grass (Sisyrinchium
septentrionale), another wetland plant.

Though not in Sheridan County, American german-
der (Teucrium canadense) was collected at a
Waterfowl Production Area nearby in Roosevelt
County. This native species had previously been
"reported" for Montana according to Dorn (1984),
and we added it to the state watch list for further
evaluation.

The fifteen significant plant species that we
identified are profiled in Appendix G, presented in
alphabetical order by scientific name. The infor-
mation includes description of each species, its
distribution in the state and the county, its habitat
in the state and the county, and comments that note
any unresolved status questions, potential threats,
or management information.

We compiled and augmented information on the
known flora of the county as well (Appendix J),
underscoring county biological diversity. There are
over 530 species of vascular plants collected or
reported from the county to date, and over 10% of
these are species not previously documented in
northeastern Montana.

Conclusions

The goal of this project was to document the
diversity of natural vegetation and plant species of
special concern in Sheridan County, and to clarify
their distribution and significance within the
county, the state, and the Great Plains. In the
process of this work, we also identified three
landscape areas within the county that support the
most intact areas of native vegetation, as well as
concentrations of significance species and vegeta-
tion types. One of these areas centers on the
Medicine Lake NWR, and another on the Missouri
Coteau prairie pothole area that has been a focus
area for the USFWS conservation easement pro-
gram. This reflects the value of the USFWS Refuge
and easement programs in helping to conserve the
county's prairie and wetland resources.

Information that we gathered has provided the basis
for updating and documenting status ranks and for
expanding and refining the vegetation classification
for Montana as a whole. This study also suggests
many opportunities that may exist to help maintain
the county's special and diverse biological re-
sources in concert with efforts to protect rangeland
values, promote watershed management, provide
hunting and other recreational opportunities, and
control noxious weeds.

While rangelands have become increasingly
fragmented, and pressures on ranchers continue or
increase, there is growing emphasis on maintaining
and enhancing rangeland soil, water, and other
natural resources. Sheridan County has many areas
with potential for showcasing the successful habitat
management that supports its diverse flora and
fauna, through collaboration among landowner and
conservation programs that support the private
landowner. We have included a cross-reference
between plant associations and the county's range
sites (Appendix G) for use in range management
coordination, planning, and education, especially in
the rolling prairie pothole landscape, alkali lake
systems, and sandhills.

Approximately half of the Sheridan County plant
species of special concern and plant associations
identified in this study are wetland features. Even
though surface connectivity between wetlands and

the Big Muddy drainage is limited, wetlands and
their vegetation components are a key part of
watershed planning.

At present, noxious weed infestations are restricted
in the county. While eight of Montana's noxious
weeds are present, they are not pervasive in native
rangeland. The Invaders Database (2000) lists
Hoary Cress (Cardaria draba). Spotted Knapweed
(Centaurea maculosa), Russian Knapweed (Cen-
taurea repens), Canada Thistle (Cirsium arvense).
Field Bindweed {Convolvulus arvensis). Leafy
Spurge {Euphorbia esula), Dalmatian Toadflax
{Linaria dalmatica), and Common Tansy
{Tanacetum vulgare) as present in Sheridan County.

One of the biggest threats to rangeland values,
watershed protection, many plant species of special
concern and native plant associations is the estab-
lishment and spread of Leafy Spurge {Euphorbia
esula). It is highly competitive and resilient, and
reported to survive underground over many years
of cultivation. It is present in the Big Muddy
drainage, including the valleybottom, some of the
adjoining ravines. Medicine Lake, and the adjoin-
ing sandhills. It is dispersed by water and wildlife,
and has the potential to expand throughout the
county, threatening rangeland values and the health
of native species and landscapes.

A number of areas and features within the county
need additional survey to better document their
distribution and status in the county. They are
listed and described below:

• In the Missouri Coteau prairie potholes area

Expand survey to re-locate many-headed

sedge {Carex sychnocephala) and northern

blue-eyed grass {Sisyrinchium

septentrionale)

Expand survey and documentation of alkali

lake plant associations

• In the Medicine Lake area

Expand survey to re-locate slender bulrush

{Scirpus heterochaetus) and pale-spike

lobelia {Lobelia spicata)

Expand survey of plains phlox {Phlox

andicola)

There is also a need for further surveys that include
but may also extend beyond Sheridan County:

• Expand the wetland vegetation sampling in the
Missouri Coteau, including the Sheridan
County segment, to better document the
diversity and nature of prairie pothole wetlands
in Montana.

• Complete wetland and grassland vegetation
descriptions and keys for the county and the
northern glaciated plains as a region. Emphasis
should be placed on further documenting all
plant associations that are restricted to the
northern Missouri Coteau region, that are
known in Montana only from Sheridan County,
or which may be uncommon range wide.

• Conduct baseline inventories of small mam-
mals, key invertebrate groups, and reptiles and
amphibians, with emphasis on species of
special concern.

Further inventory and assessment will be needed to
determine the full extent of "northern plains"
grasslands, alkali lake systems, sandhills, and
wetland complexes in the state and region, and
whether those in Sheridan County are indeed the
most extensive or highest quality of their types.

In summary, Sheridan County harbors 12 plant
species of special concern that are rare strictly from
a state perspective, and outstanding examples of
many of the 42 plant associations that are present
in the county. Fourteen of the plant associations are
newly-described or at least new to the state. Areas
of the county are remarkably intact, and range
management, noxious weed control, and related
conservation measures are important in the long-
term to these areas that support concentrations of
Sheridan County's unique biological diversity.

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Appendix A. Animal species of special concern in Sheridan County

Scientific name

Common name

Global
Rank

State
Rank

Status

Reptiles and Amphibians

Rana pipiens

Northern Leopard Frog

S3S4

Tracked

Liochlorophis vernalis

Smooth Green Snake

S2S3

Tracked

Heterodon nasicus

Western Hognose Snake

Tracked

Birds

Pelecanus erythrorhynchos

American White Pelican

S2B

Tracked

Ardea herodias

Great Blue Heron

S4B

Watch

Nycticorax nycticorax

Black-crowned Night-heron

S2S3B

Tracked

Buteo regalis

Ferruginous Hawk

S3B

Tracked

Coturnicops noveboracensis

Yellow Rail

SIB

Tracked

Charadrius melodus

Piping Plover

S2B

Tracked

Lams pipixcan

Franklin's Gull

G4G5

S3B

Tracked

Sterna caspia

Caspian Tern

S2B

Tracked

Sterna forsteri

Forster's Tern

S2B

Tracked

Chlidonias niger

Black Tern

S3B

Tracked

Athene cunicularia

Burrowing Owl

S3B

Tracked

Anthus spragueii

Sprague's Pipit

S4B

Proposed
for Watch

Lanius ludovicianus

Loggerhead Shrike

S4B

Watch

Ammodramus bairdii

Baird's Sparrow

S3S4B

Tracked

Ammodramus leconteii

LeConte's Sparrow

S1S2B

Tracked

Ammodrammus nelsoni

Nelson's Sharp-tailed Sparrow

SIB

Tracked

Insects

Hesperia ottoe

Ottoe Skipper

G3G4

Tracked

Phycioides batesii

Tawny Crescent

S2S3

Tracked

A-1

Appendix B. Equivalent scientific names for characteristic plants in Sheridan
County.

Common name

In: Booth (1950), (1966)

or Great Plains Flora

Assoc. (1986)

In: Dorn (1984)

In: Kartesz (1994)

Thickspike
Wheatgrass

Agropyron
dasystachyum

Elymus lanceolatus

Western
Wheatgrass

Agropyron smithii

Elymus smithii

Pascopyrum smithii

Little Bluestem

Andropogon scoparius

Schizachyrium scoparium

Bluebunch
Wheatgrass

Agropyron spicatum

Elymus spicatus

Pseudoroegneria spicata

Sun Sedge

Carex heliophila

Carex pensylvanica

Carex inops

Saltgrass

Distichilis spicata var.
stricta

Distichilis stricta

Distichilis spicata

Few-headed
Spike-rush

Eleocharis pauciflora

Eleocharis quinueflora

Common Milfoil

Myriophyllum spicatum

Myriophyllum
excalbescens

Water
Smartweed

Polygonum coccineum

Polygonum amphibium

Shrubby
Cinquefoil

Potentilla fruticosa

Pentaphylloides
floribunda

Lemon Scurfpea

Psolarea lanceolata

Psoralidium lanceolatum

Northern
Porcupinegrass

Stipa curtiseta

Stipa spartea
(imphcit as S. s. var.
curtiseta)

Stipa curtiseta

Green
Needlegrass

Stipa viridula

Nasella viridula

Sea Blite

Suae da depressa

Suaeda calceoliformis

B-1

Appendix C. Plant species inventory targets in Sheridan County

Scientific Name

Common Name

Global Rank

State Rank^

Agastache foeniculum

Lavender Hyssop

G4G5

SU WATCH

Agrimonia gryposepala

Common Agrimony

SU WATCH

Ammania coccinea

Scarlet Ammannia

Amorpha canescens

Leadplant

Anemone quinquefolia

Wood Anemone

Asclepias ovalifolia

Ovalleaf Milkweed

Aster frondosus

Alkali Aster

Astragalus racemosus

Creamy Poison Vetch

G5T4

Bacopa rotundifolia

Waterhyssop

Bidens frondosa

Leafy Beggarticks

SU WATCH

Carex assiniboinensis

Assiniboin Sedge

Carex bicknellii

Bicknell's Sedge

Carex gravida

Pregnant Sedge

G5T5

Carex hallii

Hall's Sedge

Carex meadii

Mead's Sedge

Carex peckii

Peck Sedge

Carex prairea

Brown-fruited Sedge

G5?

Carex sychnocephala

Many-headed Sedge

Carex tetanica

Tetan Sedge

Celastrus scandens

American Bittersweet

Centunculus minimus

Chaffweed

Chenopodium subglabrum

Slimleaf Goosefoot

G3G4

Corylus americana

American Hazelnut

Cryptantha fendleri

Fendler's Cryptantha

Cyperus erythrorhizos

Redrooted Flatsedge

Cyperus odorata

Slender Flatsedge

Cyperus rivularis

Shining Flatsedge

Cyperus schweinitzii

Schweinitz's Flatsedge

Dalea villosa var. villosa

Silky Prairie Clover

G5T?

^ Species which have blanks in the rank columns are not known to occur in Montana, but they are reported
in adjoining areas of North Dakota or Saskatchewan, and were considered in this study.

C-1

Appendix C. (cont.)

Scientific Name

Common Name

Global Rank

State Rank^

Desmodium canadense

Canada Tickclover

Eleocharis acicularis

Needle Spikerush

Eleocharis compressa

Flatstem Spikerush

Eleocharis ohtusata

Blunt Spikerush

Elodea longivaginata

Longsheath Waterweed

G4G5

Eupatorium maculatum

Joepye Weed

Gentianopsis macounii

Macoun's Gentian

Gerardia aspera

Rough Gerardia

Gerardia tenuiflora

Slenderleaf Gerardia

Geum canadense

White Avens

SU WATCH

Hutchinsia procumbens

Hutchinsia

Hemicarpha drummondii

Drummond's Dwarf Bulrush

G4G5

Hypoxis hirsuta

Yellow Stargrass

Lathyrus palustris

Marsh Peavine

Lobelia kalmii

Kalm's Lobeha

SU WATCH

Lobelia spicata

Palespike Lobelia

Mirabilis hirsuta

Hairy Four o'clock

Penstemon angustifolius

Narrow Beardtongue

Phacelia thermalis

Hot Spring Phaceha

G3G4

Phlox andicola

Moss Phlox

Plagiobothrys leptocladus

Slenderbranched Popcomflower

Polygala senega

Senica Snakeroot

Polygonatum biflorum

Solomon's Seal

Primula incana

Mealy Primrose

Prunus pumila

Sand Cherry

Psilocarphus brevissimus

Dwarf Woollyheads

Ribes hirtellum

Hairy Gooseberry

Rudbeckia hirta (R. serotina)

Blackeyed Susan

Salix petiolaris

Meadow Willow

Species which have blanks in the rank columns are not known to occur in Montana, but they are reported
in adjoining areas of North Dakota or Saskatchewan, and were considered in this study.

C-2

Appendix C. (cont.)

Scientific Name

Common Name

Global Rank

State Rank^

Scirpus heterochaetus

Slender Bulrush

Senecio congestus

Swamp Ragwort

Sisyrinichium angustifolium

Northern Blue-eyed Grass

G3G4

Solidago sparsiflora

Threenerved Goldenrod

Solidago speciosa

Showywand Goldenrod

Sorghastrum nutans

Indian Grass

Spiranthes spp.

Ladiestresses

Spiranthes cernua

Ladiestresses

Stellaria crassifolia

Thickleaved Starwort

Teucrium canadense

American Germander

SU WATCH

Vernonia fasciculata

Western Ironweed

Viburnum lentago

Nannyberry

Species which have blanks in the rank columns are not known to occur in Montana, but they are reported
in adjoining areas of North Dakota or Saskatchewan, and were considered in this study.

C-3

Appendix D. Summary table of Sheridan County plant associations

Scientific and common names of plant associations

Global
Rank

State
Rank

#of

Sample

Plots

T3
T3

O =8
%6

.a
O

Woodland

Fraxinus pennsylvanica / Primus virginiana Woodland

G3?

S2S3

Green Ash / Common Chokecherry Woodland

Populus tremuloides / Symphoricarpos albus Woodland

G3?

S3?

Quaking Aspen / Common Snowberry Woodland

Shrubland

•

Artemisia cana / Pascopyrum smithii Shrubland

Silver sagebrush - Western Wheatgrass Shrubland

Elaeagnus commutata Shrubland

G2?

S2?

Silverberry Shrubland

Eriogonum pauciflorum - Gutierrezia sarothrae Badlands Sparse Vegetation

Few-flowered Wild Buckwheat - Broom Snakeweed Badlands Sparse Vegetation

Prunus virginiana Shrubland

G4Q

Common Chokecherry Shrubland

Sarcobatus vermiculatus / Pascopyrum smithii Shrub Herbaceous Vegetation

Black Greasewood / Western Wheatgrass Shrub Herbaceous Vegetation

Shepherdia argentea Shrubland

G3G4

S3?

Buffaloberry Shrubland

Symphoricarpos occidentalis Shrubland

G4G5

S4S5

Western Snowberry Shiubland

Herbaceous

Calamovilfa longifolia - Stipa comata Herbaceous Vegetation

Prairie Sandreed - Needle-and-thread Herbaceous Vegetation

Carex atherodes Herbaceous Vegetation

G3G5

Awned Sedge Herbaceous Vegetation

Carex lanuginosa Herbaceous Vegetation

G3?

Woolly Sedge Herbaceous Vegetation

Carex praegracilis Herbaceous Vegetation

Clustered Field Sedge Herbaceous Vegetation

Distichlis spicata Herbaceous Vegetation

Saltgrass Herbaceous Vegetation

Eleocharis palustris Herbaceous Vegetation

Common Spike-rush Herbaceous Vegetation

Eleocharis quinqueflora Marl Fen Herbaceous Vegetation

Gl?

Few-flowered Spike -rush Marl Fen Herbaceous Vegetation

Elymus lanceolatus - (Koeleria macrantha) Herbaceous Vegetation

Thick-spike Wheatgrass - Prairie Junegrass Herbaceous Vegetation

Elymus lanceolatus - Stipa comata Northern Great Plains Herbaceous Vegetation

Thick-spike Wheatgrass - Needle-and-thread Northern Great Plains Herbaceous

Hordeum jubatum Herbaceous Vegetation

Foxtail Barley Herbaceous Vegetation

Oryzopsis hymenoides - Psoralidium lanceolatum Herbaceous Vegetation

G3Q

Indian Ricegrass - Lemon Scuripea Herbaceous Vegetation

Panicum virgatum - Muhlenbergia richardsonis - Schizachyrium scoparium

Switchgrass - Mat Muhly - Little Bluestem Herbaceous Vegetation

Pascopyrum smithii Herbaceous Vegetation

G3G5Q

Western Wheatgrass Herbaceous Vegetation

Pascopyrum smithii - Distichilis spicata Herbaceous Vegetation

Western Wheatgrass - Saltgrass Herbaceous Vegetation

D-1

Appendix D. (cont.)

Scientific and common names of plant associations

Global
Rank

State
Rank

#of

S ample

Plots

en s

O M

Pascopyrum smithii - Stipa comata Northern Herbaceous Vegetation

Western Wheatgrass - Needle-and-thread Northern Herbaceous Vegetation

Pascopyrum smithii - Stipa comata - Bouteloua gracilis Herbaceous Vegetation

Western Wheatgrass - Needle-and-thread - Blue Grama Herbaceous Vegetation

Pascopyrum smithii - Nassella viridula Herbaceous Vegetation

Western Wheatgrass - Green Needlegrass Herbaceous Vegetation

Polygonum amphibium Herbaceous Vegetation

G3?

Water Smartweed Herbaceous Vegetation

Potamogeton pectinatus - Myriophyllum spicatum Herbaceous Vegetation

G3G4

SIQ

Sago Pondweed - Common Water-milfoil Herbaceous Vegetation

Puccinellia nuttalliana Herbaceous Vegetation

G3?

Nuttall's Alkaligrass Herbaceous Vegetation

Ruppia maritima Great Plains Herbaceous Vegetation

Widgeon-grass Great Plains Herbaceous Vegetation

Salicornia rubra Herbaceous Vegetation

S2?

Red Glasswort Herbaceous Vegetation

Schizachyrium scoparium - Muhlenbergia cuspidata Herbaceous Vegetation

G3?

Little Bluestem - Plains Muhly Herbaceous Vegetation

Scirpus acutus Herbaceous Vegetation

Hardstem Bulrush Herbaceous Vegetation

Scirpus maritimus Herbaceous Vegetation

Alkali Bulrush Herbaceous Vegetation

Scirpus pungens Herbaceous Vegetation

G3G4

Common Threesquare Herbaceous Vegetation

Scolochloa festucacea Herbaceous Vegetation

G4G5

Sprangletop Herbaceous Vegetation

Spartina pectinata Herbaceous Vegetation

G3?

Prairie Cordgrass Herbaceous Vegetation

Stipa comata - Bouteloua gracilis Herbaceous Vegetation

Needle-and-thread - Blue Grama Herbaceous Vegetation

Stipa comata - Psoralidium lanceolatum Herbaceous Vegetation

Needle-and-thread - Lemon Scurfpea Herbaceous Vegetation

Stipa curtiseta Herbaceous Vegetation

Northern Porcupinegrass Herbaceous Vegetation

Triglochin maritimum Herbaceous Vegetation

Common Arrow-grass Herbaceous Vegetation

Typha latifolia Western Herbaceous Vegetation

Common Cattail Western Herbaceous Vegetation

Undescribed types

Calamagrostis stricta Herbaceous Vegetation

Narrow-spiked Reedgrass Herbaceous Vegetation

Carex aquatilis Great Plains Herbaceous Vegetation

Water Sedge Herbaceous Vegetation

Crataegus chrysocarpa Woodland

Yellow -fruit Hawthorn Woodland

Pentaphylloides floribunda / Stipa curtiseta Shrubland

Shrubby Cinquefoil / Northern Porcupinegrass Shrubland

Elymus lanceolatus - Bouteloua gracilis Herbaceous Vegetation

Thick-spike Wheatgrass - Blue Grama Herbaceous Vegetation

D-2

Appendix D. (cont.)

S cientific and common names of plant associations

Global
Rank

State
Rank

#of

Sample

Plots

T3
T3

en s

Elymus trachycaulus Herbaceous Vegetation

Bearded Wheatgrass Herbaceous Vegetation

Elymus trachycaulus - Distichlis spicata Herbaceous Vegetation

Bearded Wheatgrass - Saltgrass Herbaceous Vegetation

Elymus trachycaulus - Spartina gracilis Herbaceous Vegetation

Bearded Wheatgrass - Alkali Cordgrass Herbaceous Vegetation

Juniperus horizontalis / Elymus lanceolatus Shrubland

Creep ing Junip er / Thick-sp ike Wheatgrass Shrubland

Panicum virgatum - Spartina pectinata Herbaceous Vegetation

Switchgrass - Prairie Cordgrass Herbaceous Vegetation

Pascopyrum smithii - Bouteloua gracilis Herbaceous Vegetation

Western wheatgrass -Blue Grama Herbaceous Vegetation

Sarcobatus vermiculatus / Distichlis spicata - (Puccinellia nuttalliana) Saline Shrub

Black Greasewood / Saltgrass - (Nuttall's Alkaligrass) Saline Shrub Herbaceous

Scirpus nevadensis Herbaceous Vegetation

Nevada Bulrush Herbaceous Vegetation

Spartina gracilis Herbaceous Vegetation

Alkali Cordgrass Herbaceous Vegetation

Stipa comata - Muhlenbergia cuspidata Herbaceous Vegetation

Needle-and-Thread - Plains M uhly Herbaceous Vegetation

D-3

Appendix E.

Sheridan County
Plant Associations

Plant associations are presented in eight sets.
The first four are herbaceous. They are listed
alphabetically by dominant species within each set.

Characteristic Grassland Types

Minor and Under Review Grassland Types

Wetland Types

Wetland Types Under Review

Shrubland Types

Shrubland Types Under Review

Woodland Types

Woodland Types Under Review

Types that are newly-proposed with documentation
are automatically assigned state and global ranks
with a question mark, pending review inside and
outside the state. Types that do not fit existing
classifications and do not have adequate
documentation in this study to propose them for
addition have state and global ranks omitted.

C haracteristic G rassland
Types

Grasslands are the most extensive natural vegeta-
tion in Sheridan County historically and at present.
The following plant associations are common or
well-developed types that are characteristic of the
county. Grasslands are also referred to as prairie or
steppe. A few grass-dominated plant associations
are wetland types, treated separately.

Native grass dominants are commonly
characterized by stature, growth form, and
photosynthetic pathway. The following plant
associations include many complementary
"species-pairs" of contrasting characteristics. Mid-
height grasses and short grasses are often paired
together, hence the characterization of the
prevailing plains vegetation as "mixed grass
prairie." Bunch-forming grasses and rhizomatous
grasses are often present together, also contributing
to the pattern of grassland cover and enhancing
water adsorption abilities. Cool-season grasses
increase with importance at these northern
latitudes, but warm-season grasses like blue grama
are often present in abundance with peak
photosynthetic efficiency at warm temperatures.

The most widespread Sheridan County grassland
plant associations correspond within the silty range
site, comprised of midgrass species with or without
a shortgrass component. This is also among the
most arable range sites and the most productive
rangeland, present in fragments throughout the
county. Sand prairie plant associations are
restricted mainly to the Medicine Lake sandplains.
We could only begin to characterize grasslands of
fine-textured valley soils because this habitat has
been widely converted and altered, with exception
of the more salt-affected and poorly-drained
settings. We had a dual focus of documenting the
outstanding examples of widespread, representative
grassland types and the best remaining examples of
other well-developed types that are more restricted
by nature or by land-use history.

Elymuslanceolatus- Stipa comata

N orthern G reat Plains H erbaceous

Vegetation

T hick-spike Wheatgrass- Needle-and-thread
H erbaceous Vegetation

Global rank: G? State rank: S?

Summary: The thick-spike wheatgrass - needle-
and-thread herbaceous vegetation is a productive
prairie plant association found in the northern
Great Plains provinces and areas of adjoining states
in glaciated landscapes on well-drained slopes with
fine-textured soils, and on gently rolling uplands of
silt or silt loam. It may be restricted to the
northeasternmost corner of Montana and adjoining
glacial drift plains and the collapsed moraine of
Saskatchewan and North Dakota where the topog-
raphy is gentle, and may have been a prevalent
plant association. It is a priority for exchanging
vegetation and range management information with
ecologists from North Dakota and Saskatchewan.
It is presented in this study as a "new" plant
association, though it has been previously sampled
and treated as part of other plant associations.

In Sheridan County, it is a major part of the prairie
pothole landscape mosaic in the northeastern
corner, also scattered in the drift plains to the south
and west and in limited areas elsewhere. It may
have been one of the most widespread plant
association types in the county. Most large tracts of
it have been plowed.

E-1

Vegetation: This plant association has a graminoid
cover of 90-100%, and both Elymus lanceolatus
and Stipa comata usually have at least 30% of total
graminoid cover. It is a midgrass plant association
that has a minor component of short graminoids,
most often including sedges {Carex stenophylla, C.
filifolia) and traces of blue grama (Bouteloua
gracilis). Species diversity is moderate compared
to other grassland associations, and there are no
forb species reaching their highest cover values
here with the possible exception of white milkwort
(Polygala alba), reflecting the "melting pot" nature
of this plant association type. Other common
associated species include Hood's phlox (Phlox
hoodii), yarrow (Achillea millefolium), Pasque-
flower (Anemone patens) and American vetch
(Vicia americana).

Environment: The typical setting for this plant
association type is on dry, well-drained upland
slopes on fine-textured soils. Some of the best
examples in Sheridan County were found on the
more gently -rolling of Missouri Coteau prairie
pothole areas, all mapped as part of Zahill-Will-
iams-Dimmick complex, and on glacial drift with
Lambert silty clay loams in upland escarpment
areas in the southwestern portion of the county. It is
not only a prevalent upland type but an intermedi-
ate feature along slope and topographic position
gradients; common on toeslopes and the well-
drained areas of bottomland along the Big Muddy
Creek valley where the Havrelon silt loam contains
a distinctly sandy component or inclusion.

Comments: This cool-season, mid-grass plant
association is distiniguished by thick-spike wheat-
grass (Elymus lanceolatus) as co-dominant, replac-
ing western wheatgrass (Pascopyrum smithii) as
the most widespread wheatgrass in the northern
Missouri Coteau of northwestern North Dakota and
northeastern Montana (Heidel pers. obs.). This
vegetation phenomenon has not been published in
the technical literature to our knowledge.

Elymuslanceolatus- (Koeleria macrantha)
H erbaceous Vegetation

Thick-spike Wheatgrass- Prairiejunegrass
H erbaceous Vegetation

Global rank: G?; State rank: S?

Summary: The thick-spike wheatgrass - prairie
junegrass herbaceous vegetation is a productive
prairie plant association found in the northern
Great Plains provinces and northernmost areas of
adjoining states in glaciated landscapes on fine
textured soils. It is prevailing vegetation on clay
deposits occupying the beds of former glacial lakes
in the provinces, and otherwise a mosaic compo-
nent on the finely-textured clay loam and silt loam
soils on outwash channels and till deposits in both
states and provinces. It is presented in this study as
a "new" plant association, though it has been
previously sampled and described in related
Canadian vegetation classification systems.

In Sheridan County, it is an integral part of the
prairie pothole landscape mosaic in the northeast-
ern corner, and scattered widely across the rest of
the county on top of gentle hills and ridges, as well
as on benches and terraces of glacial meltwater
valleys. It has been plowed as it occurred on level
terrain elsewhere.

Vegetation: This plant association has a graminoid
cover of 70-100% with Elymus lanceolatus making
up at least half of total cover and is sometimes the
sole dominant. Koeleria macrantha is present and
variously comprises less than 1% to almost half of
total cover. It is a midgrass plant association that
has a minor component of short graminoids, most
often including sedges (Carex stenophylla, C.
filifolia) and traces of blue grama (Bouteloua
gracilis). It usually appears dense and homoge-
neous, occasionally interrupted by relatively sparse
pockets of forbs in patches. The number of differ-
ent forb species and their abundance tend to be
very low. The most common and characteristic
associated species include blue flax (Linum
lewisii), spiny goldenweed (Machaeranthera
pinnatifida), and red globe-mallow (Sphaeralcea
coccinea). Total forb canopy cover is less than 5%.

This is one of the more species-poor upland
associations in the study area, as indicated by mean
number of species per vegetation sampling plot, yet
it is also one of the most productive, and lends
itself to both landscape structural heterogeneity and

E-2

mosaic richness. Intact prairie pothole tracts may
represent some of the best-developed and most
extensive examples in Montana.

Environment: The typical environment for this
plant association type has been characterized as
lacustrine clay soils that were deposited as glacial
lake beds (Coupland 1950, 1960). It was prevalent
in this habitat but the landscape has been exten-
sively broken in the provinces, and is poorly
represented further south in Montana, where at one
representative glacial lakebed site it appears that
western wheatgrass (Pascopyrum smithii) achieves
dominance with green needlegrass (Nasella
viridula; Cooper and Heidel 1999).

The typical Canadian environment where it was
prevalent provides a context for understanding its
environment at the southern limits of its range. In
the Missouri Coteau of Sheridan County, is wide-
spread in mosaic and large patch patterns on
collapsed moraine, where it is consistently present
at high points on the landscape. It encompasses the
near-level upland segments of the silty and clayey
range sites. It is consistently found on Zahill series
soils derived from clay loam glacial till; often in
mosaic patterns combined with the Williams series
on steeply rolling collapsed moraine simply
mapped as Zahill-Williams complex, hilly, 15-25%
slope (Richardson and Hanson 1977). Despite the
rolling nature of the landscape, this plant associa-
tion is restricted to nearly level (0-5%) upland
hilltop positions where its extent is determined in
large part by the degree that the landscape includes
level terrain.

Comments: The two major species of wheat-
grasses have the highest productivity among
dominant mixed grass prairie species (Coupland
1950). Thick-spike wheatgrass achieves much
higher density and canopy cover than western
wheatgrass (Heidel pers. obs). Clipping studies
have documented that the "wheatgrass-junegrass
faciation" has the highest forage yield (tons acre) in
the mixed grass prairie landscape (Coupland 1950).
Where Elymus lanceolatus - (Koeleria macrantha)
Herbaceous Vegetation makes up more than a trace
of primary range, the task of maintaining or restor-
ing its condition is important in planning livestock
use while maintaining cover, productivity, and
landscape diversity. It is subject to heavy litter
build-up and declines in forb numbers under idle
conditions.

Oryzopashymenoides- Psxalidium
lanceolatum H erbaceous Vegetation

I ndian Ricegrass- Lemon Scurfpea
H erbaceous Vegetation

Global rank: G3Q; State rank: S?

Summary: The Indian ricegrass - lemon scurfpea
herbaceous vegetation is a sparse grassland re-
stricted to slopes and crests of sand dunes recently
disturbed by wind erosion (Lesica 1987). It is the
driest and earliest successional stage of grassland
types on sandplains. It may be distributed in
adjoining states and provinces where dunes formed,
e.g., in association with glacial lakes. Within
Montana, the Medicine Lake sandhills are the
largest area where it is known. Even though it
covers a very small area in the county, it is consid-
ered a defining point of reference in sandhills
succession.

Vegetation: The sparse graminoid cover is domi-
nated by Oryzopsis hymenoides, usually comprising
20% or less canopy cover. Sand dropseed
(Sporobolus crytandrus) is present, and more
abundant in this association than elsewhere on the
landscape, comprising up to 10% cover. Other
grasses present include sand bluestem (Andropogon
hallii) and needle-and-thread (Stipa comata). Grass
cover is often approached or exceeded by the forb
cover of Psoralidium lanceolatum, with values of
20% or greater. Wild begonia (Rumex venosus) is
also characteristic of this setting, and two rare
species are almost restricted to this habitat, includ-
ing Schweinitz' flatsedge (Cyperus schweinitzii)
and smooth goosefoot (Chenopodium subglabrum).
The Fendler cat's-eye (Cryptantha fendleri) is
another rare plant that is present here, but it is not
restricted to this plant association.

Environment: This plant association is found in
blow-outs, and is the driest and earliest stage of
succession making up the sands range site. There
is no soil development, and almost all of the
groundcover is bare, unconsolidated sand. This
habitat is maintained by the forces of wind.

Comments: This plant association is affected by
efforts to heal dune blowouts and stabilize
sandhills. Crested wheatgrass (Agropyron
cristatum) has been seeded and widely-established
in some pastures of the Medicine Lake sandhills.

E-3

Even in this harshest of sandhills grassland types,
leafy spurge (Euphorbia esula) has become estab-
lished, signifying the potential of this noxious
species to occupy the full range of sandhills
habitats barring intervention.

PasDopyrum smith! i - Stipa comata -
Bouteloua gradlisH erbaceous Vegetation

Western Wheatgrass- Needle-and-thread -
Blue Grama H erbaceous Vegetation

Global rank: G4; State rank: S4

Summary: The western wheatgrass - needle-and-
thread - blue grama herbaceous vegetation is a
widespread Great Plains type centered in North and
South Dakota, Montana and Wyoming, extending
into adjoining states and provinces. It is prevalent
in unglaciated plains within the "mixed grass
prairie zone," widespread across the unglaciated
"shortgrass prairie zone," and common to prevalent
in the glaciated Great Plains. It is codominated by
Pascopyrum smithii, Stipa comata, and Bouteloua
gracilis.

In Sheridan County, it is found on well-drained
benches and terraces along Big Muddy and Wolf
Creeks, and to some extent on the Flaxville Gravel
uplands to the west. The uplands around nearby
Homestead Lake NWR appear to have this associa-
tion, though perhaps with more Koeleria
macrantha than Pascopyrum smithii, and abun-
dance of Artemisia biennis that may indicate a
history of heavy grazing.

Vegetation: This plant association is co-dominated
by mid- and short-height grasses, with generally
high vegetation cover of 60-100%, and intermedi-
ate productivity. Pascopyrum smithii and Stipa
comata are mid-height grasses usually totaling over
half of net canopy cover, and prairie junegrass
(Koeleria macrantha) is also present in most
stands, but usually contributing 10% or less cover.
The cover of Bouteloua gracilis, a shortgrass
species, is usually comparable or exceeding that of
the midgrass species, sometimes replaced by
thread-leaved sedge (Carex filifolia) or sun sedge
(C. heliophila). Typical forbs include Hood's phlox
(Phlox hoodii), red globe-mallow (Sphaeralcea
coccinea), scarlet gaura (Gaura coccinea), white
penstemon (Penstemon albidus), rush-like
skeletonweed (Lygodesmia juncea), fringed sage

(Artemisia frigida), Nuttall's pussy-toes
(Antennaria microphylla), purple prairie clover
(Dalea purpurea) and rough pennyroyal (Hedeoma
hispidum). In southeastern Montana and northeast-
ern Wyoming, stands of this association often
contain big sagebrush (Artemisia tridentata ssp.
wyomingensis) though at cover values too low for
this association to be considered shrubland or shrub
herbaceous vegetation.

Environment: This plant association is found on
flat or gently sloping terrain ranging from valley
toeslopes to uplands. Surface layers of soils are
usually clay loams, although stands of this type
may also be found on loams, silt loams, silty clays
and clays (Hanson and Whitman 1938, Hansen and
Hoffman 1988). In Alberta and Saskatchewan this
association grows on loamy sands to sandy loams
in the center of the plains (Coupland 1960).

Comments: The cover contribution oi Pascopyrum
smithii and Bouteloua gracilis have been found to
vary inversely in periods of drought or high rain-
fall, so that plots originally read in drought years
dominated by Stipa comata - Bouteloua gracilis
were re-read over a decade later and determined to
include western wheatgrass co-dominance
(Coupland 1960). The midgrass component also
declines under heavy grazing.

Exotic brome grasses, especially hairy brome
(Bromus commutatus) and cheatgrass (B. tectorum),
are present in many stands of this association and
they commonly contribute substantial cover
(Hanson and Dahl 1956, Hansen et al. 1984,
Hansen and Hoffman 1988).

Stipa comata - Psxaiidium ianceoiatum
H erbaceous Vegetation

N eedle-and-thread - Lemon Scurfpea
H erbaceous Vegetation

Global rank: G?; State rank: S?

Summary: The needle-and-thread - lemon
scurfpea herbaceous vegetation is restricted to
wind-blown sand deposits with undeveloped soils,
spanning almost all topographic positions except
swales. It is found on both choppy dunes and
rolling plains. It is thought to represent a serai stage
between the barely- stabilized open dune vegetation
with Indian ricegrass - lemon scurfpea plant
association (Oryzopsis hymenoides - Psoralidium

E-4

lanceolatum) and the western wheatgrass - needle-
and-thread plant association (Pascopyrum smithii -
Stipa comata; Lesica 1987a). It is presented in this
study as a "new" type, though it has been previ-
ously reported in this earlier work, but not de-
scribed or incorporated in the state classification to
date.

The distribution may include dunes formed in
association with glacial lakes in adjoining states
and provinces. The Medicine Lake Sandhills are
the largest setting where it is known from in
Montana.

Vegetation: Grass cover, almost all of which is
Stipa comata, is generally 20-40%, and forb cover
represented primarily by Psoralidium lanceolatum
approaches or exceeds it. Despite comparatively
high cover values, litter accumulation is low and
bare soil is exposed at the surface (20-60%).
Characteristic species include Fendler cat's-eye
(Cryptantha fendleri), purple prairie clover (Dalea
purpurea), and western spiderwort {Trade scantia
occidentalis). Grazing increasers are consistently
present, but take on high cover values where
grazing has induced shift in dominance. The
increasers include biennial wormwood (Artemesia
biennis), brittle pricklypear (Opuntia fragilis), and
hoary aster (Machaeranthera canescens).

Environment: This plant association occurs on
stabilized and semi- stabilized sandhills. The
topography of the reworked sand is irregularly
rolling to choppy, forming very many dips and
rises. The Medicine Lake sandhills and fringes are
mapped as Blanchard fine sands, 4-20 degrees
slope, and the plant association represents the
prevalent form of "sands range site" in the county.
Soil profile development is limited and litter
accumulation is low so that bare sand is visible at
the surface. The affects of wind erosion are limited,
baring concentrated use as around windmills, or
major reductions in standing cover.

Comments: Medicine Lake sandhills infestations
of leafy spurge (Euphorbia esula) occur within this
type, at early stages of invasion.

Stipa curtiseta H erbaceous Vegetation

N orthern Porcupinegrass H erbaceous
Vegetation

Global rank: G?; State rank: S?

Summary: The northern porcupinegrass herba-
ceous vegetation is an extremely productive prairie
type of sheltered hillslopes in prairie pothole and
prairie parkland regions of the provinces and
adjoining northern Great Plains states. It is rich in
species numbers, particularly forbs, and includes
grasses and forbs that are restricted to or reaching
their peak frequency in this plant association
compared with surroundings. It corresponds with
the Stipa spartea var. curtiseta - forb community
described by Redmann (1975) from one plot on a
north-facing slope, north of the Missouri River in
western North Dakota.

In Sheridan County, it had been previously reported
from Medicine Lake NWR (Cooper and Heidel
1999) under the plant association name for it from
the Canadian Prairie Parklands, Stipa curtiseta -
Elymus lanceolatus Herbaceous Vegetation. It is
presented in this study as a "new" plant association
of the northern plains, building upon the earlier
one-plot studies, and distinct at some level from the
Stipa curtiseta - Elymus lanceolatus Herbaceous
Vegetation of the Canadian Parklands.

Vegetation: The northern porcupinegrass herba-
ceous vegetation has over 70% cover of northern
porcupinegrass {Stipa curtiseta), and total canopy
cover approaching or exceeding 100% with the
bunchgrass life-form giving it a densely-tufted
appearance. Shrub cover ranges from 1-10% and
variably includes prairie rose {Rosa arkansana),
western snowberry {Symphoricarpos occidentalis),
and sometimes silverberry {Elaeagnus commutata).
Small-winged sedge {Carex stenophylla) is usually
present and spike-oat {Helictotrichon hookeri) is
restricted to this plant association in the study area.
Among the diverse forbs, pasqueflower {Anemone
patens), old man's whiskers {Geum triflorum) and
northern hedysarum {Hedysarum boreale) are
particularly abundant. Remann (1975) describes a
unique feature of this plant association as the
abundance of moss understory in places, a phenom-
enon that was noted in this study as well. The
bryophyte flora and role may be important to exam
further.

E-5

Environment: The typical setting for this plant
association is on glacial till, usually restricted to
cool, moist north-facing slopes with loamy soils.
The most examples were found in the Missouri
Coteau prairie pothole areas around Comertown,
but it was also noted where glacial meltwater cut
through till or outwash. Soils in the former are
mapped as Zahill- Williams complex, hilly. The
soils are well-drained, and mantled by a deep layer
of litter exposing little or no bare soils. Some sites
seemed to have such dense root networks as to
form turf. The association is limited by both slope
and aspect to relatively steep, mainly north-facing
slopes of 10% or greater.

Comments: This plant association type may be the
most productive of all upland grassland types in the
study area. Northern Porcupine grass had the
highest yield per basal area percentage compared to
all other prairie grasses in the Canadian northern
Great Plains except for rough fescue (Festuca
scabrella; Coupland 1960), which was not found in
the county. However, the awns of northern porcu-
pine grass deter grazing during the early summer
period of peak growth and yield according to
ranchers.

Response to fire has been tested on Medicine Lake
National Wildlife Refuge, warranting close investi-
gation and documentation. Despite the consistent
presence of woody vegetation, there were no sites
observed where shrubs appeared to be encroaching
and assuming dominance.

It was characterized as the ''Stipa curtiseta -
Elymus lanceolatus Herbaceous Vegetation" in
Cooper and Heidel (1999) from one station in
Medicine Lake National Wildlife Refuge, follow-
ing the convention of Canadian literature as a
Parkland plant association in which wheatgrass
cover approaches or exceeds needlegrass cover. We
provisionally present it here as a separate plant
association in considering the paucity of thick-
spike wheatgrass in all sample plots. The separate
association of northern porcupinegrass - thick-spike
wheatgrass is under research in Valley County
(Cooper in prog.).

Classification Comments: Stipa curtiseta forms
monodominant stands in the Missouri Coteau,
whereas it is closely associated with Elymus
lanceolatus on drift plains and escarpments. The
Stipa curtiseta type is presented separately from the
Elymus lanceolatus - Stipa curtiseta type because

of its distinct species richness and composition, as
well as distribution. The latter type is being docu-
mented in Valley County, after which further
comparison and analysis is warranted. The only
settings where Stipa curtiseta is reported as single-
species dominant in Canada are on steep, dry
slopes of the parkland zone.

M inor and U nder Review
Grassland Types

The following types are characterized as "minor" in
the parts of the county where study was focused,
generally occupying small areas or with limited
development. There are also types that are
presented as under review which do not fit existing
or proposed classifications.

Calamwilfa longi folia - Stipa comata
H erbaceous Vegetation

Prairie San dreed - Needle-and-thread
H erbaceous Vegetation

Global rank: G3; State rank: S?

Summary: The prairie sandreed - needle-and-
thread herbaceous vegetation occurs in the central
Great Plains region, e.g., the Nebraska Sandhills,
and less extensive to the north. Stands occur on
stabilized sand dunes, as well as in interdunal
valleys, and colluvial sands. Soils are medium to
fine sands formed either from eolian or colluvial
processes. The vegetation has an open canopy,
dominated by mid- to tall grasses. Calamovilfa
longifolia and Stipa comata are the most
conspicuous and dominant grasses. Other common
grasses include blue grama (Bouteloua gracilis),
prairie junegrass (Koeleria macrantha), Indian
ricegrass (Oryzopsis hymenoides), and sand
dropseed (Sporobolus cryptandrus).

It is included among the suite of plant associations
making up the Medicine Lake sandhills, all mapped
as Blanchard fine sands, 4-20 degree slopes;
corresponding with sands range sites. It does not
appear to be a widespread plant association in the
Medicine Lake sandhills as originally postulated
(Cooper and Heidel 1999), but occurs in small
patches on low ridges and in poorly-sorted mosaic

E-6

patterns on gentle plains of Medicine Lake
surrounding sandplains under certain grazing
regimes. One of the more extensive areas of it
along Sand Creek (plot 007) was used for early-
season grazing as a calving pasture, and had high
cover of blue grama (Bouteloua gracilis.) With
more soil development on sandy loams, it appears
that Pascopyrum smithii - Stipa comata
Herbaceous Vegetation prevails. It might otherwise
be present around sandstone escarpments in the
state, and Calamovilfa longifolia was noted in local
abundance on sandstone west of Antelope in
association with thread-leaved sedge
(Carexfilifolia). In any case, plant associations
with prairie sandreed are not widespread in
Sheridan County, and they warrant further
evaluation in the state.

E lymuslanceolatus- Bouteloua gracilis
H erbaceous Vegetation

T hick-spike Wheatgrass- Blue Grama
H erbaceous Vegetation

Summary: An upland area co-dominated by thick-
spike wheatgrass and blue grama occurred in silt
loam uplands strewn with rock, above an alkaline
lake. This unusual combination does not have a
corresponding vegetation description, so it is noted
here as an undescribed, provisional type under
review. Some of the more stress-tolerant species
present include Atriplex gardneri and Astragalus
pectinatus.

Pascopyrum anithii - Bouteloua gracilis
Northern Plains IH erbaceous Vegetation

Western Wheatgrass - Blue G rama
H erbaceous Vegetation

Summary: The western wheatgrass - blue grama
herbaceous vegetation is provisionally identified as
a northern Great Plains plant association of hot
alluvial settings and thinsoil settings overlying
shale that are saturated in spring but dry for most of
the growing season. It corresponds with the
Bouteloua-Agropyron Faciation of Coupland
(1960). Western wheatgrass comprises at least
20% cover and blue grama cover is about twice as

much as western wheatgrass cover. Species
diversity is low, and the characteristic forbs include
plains pricklypear (Opuntia polyacantha), yellow
flax (Linum rigidum), and rough pennyroyal
(Hedeoma hispida).

Sheridan County examples were documented in
valleybottom settings along the Big Muddy Creek
and in small areas of Sand Creek. It was also found
to be locally common on the rolling uplands above
alkali lakes. Though the latter is an upland setting,
the soils are ustiflu vents.

Classification comments: There is also a

Pascopyrum smithii - Bouteloua gracilis plant
association recognized from foothill and lower-
montane valleys of southwestern states. The
northern Great Plains examples are treated
separately because of non-overlapping climate and
setting. However, intervening examples and
additional vegetation comparison may link these
plant associations that are provisionally treated as
distinct.

The Pascopyrum smithii - Bouteloua gracilis plant
association grades into the Pascopyrum smithii -
Distichilis spicata plant association with increase
in salinity. It grades into the Pascopyrum smithii
plant association with intermittent flooding.

This plant association is typical of the clayey range
site. Additional vegetation sampling is needed to
document and describe it.

Pascopyrum anithii - Distichlis spicata
H erbaceous Vegetation

Western Wheatgrass - Saltgrass H erbaceous
Vegetation

Global rank: G4; State rank: S?

Summary: The western wheatgrass - saltgrass
herbaceous vegetation has been described for
mainly unglaciated landscapes of Wyoming,
Nebraska, and North Dakota in depressions and on
stream terraces on deep, moderately saline soils,
sometimes with a clay subsoil and is also present in
alkali lake systems of the prairie pothole region. It
is treated as a wetland type, on soils that are wet for
part of the year and may flood periodically. This
plant association is dominated by graminoids, and

E-7

most of the vegetation is 0.6 m or less. The
dominants are Pascopyrum smithii and Distichlis
spicata. Woody plants are minor species, but big
sagebrush {Artemisia tridentata subsp.
Wyomingensis), silver sagebrush (Artemisia cana
subsp. cana), sandbar willow (Salix exigua), and
plains Cottonwood (Populus deltoides) are present
in some stands. Forbs that may be present are
marsh elder (Iva annua), prairie sunflower
(Helianthus petiolaris), Indian- wheat (Plantago
patagonica), broom snakeweed (Gutierrezia
sarothrae), and white-prairie aster (Aster falcatus).

In Sheridan County, the best-developed examples
were found at alkali lakes of the Missouri Coteau
on rolling, salt-affected glacial outwash uplands
where salts rise to the surface. Soils are silty clay
ustifluvents or Zahill clay loam. This plant
association is also present in small areas of the Big
Muddy and Wolf Creek valleys where it is
temporarily inundated in spring or after heavy
rains. Some sites are clearly in upland settings, but
more information is needed on soils and hydrology
to determine whether they are wetland or
terrestrial. Terrestrial forms may be more closely
allied with the upland Distichilis spicata plant
association. This plant association has low species
diversity, and exotic species including yellow
sweetclover (Melilotus ojficinalis), are present
though only in trace amounts.

Pascopyrum smithii - Nasasiia viriduia
H erbaceous Vegetation

Western Wheatgrass - G reen N eedlegrass
H erbaceous Vegetation

Global rank: G4; State rank: S4

Summary: The western wheatgrass - green
needlegrass plant association type is widespread
across much of the northern Great Plains. Stands
occur in narrow valleys, on stream terraces, and on
some uplands (Jones 1992, USPS 1992). Soils are
fine-textured, including clays, silty clays, clay
loams, or rarely loams, and moderately-drained.
The soil profile is typically well developed. The
parent material is siltsone and mixed sedimentary
rock (USPS 1992). This plant association usually
occurs on level or nearly level ground but
sometimes may be on moderate slopes of any
aspect. Most of the documentation for this type

comes from unglaciated landscapes, and its
distribution and environmental attributes in
glaciated settings need more work.

In Sheridan County, this is a minor type and was
noted in only one valleybottom setting along Pagle
Creek in the Big Muddy headwaters area. Most
valleybottom settings for in the western part of the
county are too dry or salt-affected for it. It
represents the highly productive "overflow" range
site.

Pascopyrum smithii - Stipa comata
N orthern H erbaceous Vegetation

Western Wheatgrass- Needle-and-thread
Northern H erbaceous Vegetation

Summary: The western wheatgrass - needle-and-
thread northern herbaceous vegetation as expressed
in Sheridan County occupies stable northern
sandplains and medium-textured uplands on gentle
and nearly-level slopes. It is a highly-productive
vegetation and may have been a prevailing type on
the drift plains. The poor competitive ability of
blue grama (Bouteloua gracilis) in this northern
setting is reflected in the great reduction in
shortgrass components except in drought episodes
(Coupland 1960).

In the study area, it is found at opposite corners of
the county. It spans the gentle sandplain skirting the
Medicine Lake sandhills, on Lihen loamy fine
sand, 0-6 % slope; and locally repeats in swales
and flats within the sandhills. It is also found on
Williams loam across the tablelands adjoining the
Big Muddy headwaters. It may be an prevailing
type, but surveys were incomplete for making this
characterization and much of the habitat has been
converted to cropland.

E-8

Schizachyrium scoparium - (Muhlenbergia
cuspidata) H erbaceous Vegetation

Little Bluestem - Plains M uhly H erbaceous
Vegetation

Global rank: G3?; State rank: S2

terrain, at Medicine Lake on sandy loam at the
highest point of Big Island, and along south-facing
ravine slopes south of the Lake. Soils range from
well-drained clay loams to sandy loams and
"shallow to gravel range sites", and it is most
commonly characterized as a "sandy range site".

Summary: The little bluestem - plains muhly
herbaceous vegetation is on well-drained, often
erodible hillslopes with soils formed in fine-
textured glacial till or shale parent material. It is
dominated by the two midgrasses, with high cover
where little bluestem forms large bunches, and low
cover where the cover of plains muhly is 5% or
greater. It is mainly on the upper half of exposed
southern and western slopes where topography is
broken along ravines, valley breaks, and
escarpments. This corresponds with the
Andropogon spp. community described by
Redmann (1975) from ravine slopes north of the
Missouri River in western North Dakota.

In Sheridan County, it is well-developed along
ravines off the Big Muddy valley, on Zahill clay
loam, steep (15-45%), with high gravel content.
They are widely-scattered south and west of the
Big Muddy valley on erodible upper slopes
stabilized by bunchgrasses.

Stipa comata - Boutdoua gradlis
H erbaceous Vegetation

Needle-and-thread - Blue Grama Sedge
H erbaceous Vegetation

Global rank: G5; State rank: S5

Summary: The needle-and-thread - blue grama -
thread-leaved sedge herbaceous vegetation is
common in the unglaciated northern Great Plains
and on dry microhabitats of the glaciated plains.
Stands occur on flat to rolling upland topography
with well-drained, usually sandy loam to loam
soils. Stipa comata is the tallest of the dominant
species, and the warm-season bunchgrass,
Bouteloua gracilis is abundant, often along with
Carex filifolia.

In Sheridan County, it is found on the most
exposed microhabitats of rolling prairie pothole

Stipa comata - Muhlenbergia cuspidata
H erbaceous Vegetation

N eedle-and-thread - Plains M uhly
H erbaceous Vegetation

Summary: Plant associations dominated by
needle-and-thread and plains muhly occur on
sparse, early-succession grassland on steep,
exposed, fine-textured slopes. Total vegetation
cover is usually less than 40%. The cover of plains
muhly is 10% or greater, sometimes comprising
over half of total graminoid cover. Early succession
shrubs are often present in trace amounts including
skunkbush sumac {Rhus frilobata) and silver
sagebrush {Artemisia cana). Characteristic forbs
include shining penstemon {Penstemon nitidus),
bastard toadflax {Commandra umbellata), dotted
blazing-star {Liatris punctata), and round-leaved
thermopsis {Thermopsis rhombifolia).

In Sheridan County, it was observed on the most
exposed of ravine slopes along the upper Big
Muddy valley, on silty-clay of the Lambert-Zahill
complex, 20-50%.

Wetland Types

Wetlands are common in parts of Sheridan County,
and cover approximately 4% of the total county
surface area (40,868 acres; USDI National
Wetlands Inventory Statistics). The most extensive
and certainly the most numerous of wetlands are
palustrine types (Cowardin et al. 1979), i.e.,
shallow wetlands more commonly referred to as
marshes, sloughs, or swales. This study focused on
palustrine vegetation, and more particularly the
emergent forms to a depth of 1 m. Palustrine
wetlands comprise 53% of the wetland area in the
county (Figure F-1). Lacustrine wetlands include
the largest lake in the county. Medicine Lake, and

E-9

Wetlands in Sheridan County, Montana

Lacustrine
46%

Figure F-1

the deepest lake in the county, Brush Lake. They
represent openwater systems usually greater than
20 acres, and with water depth greater than 2 m or
else having characteristic features like a wave-
formed shoreline (Cowardin et al. 1979). By this
latter criteria, they also includes the most alkaline
water bodies in the county. Lacustrine wetlands in
the county total 18,776 acres. Riverine wetlands
are restricted mainly to the Big Muddy Creek and
total only 317 acres.

The plant associations are cross-referenced to the
wetland types and vegetation types of Cowardin et
al. (1979), Hansen et al. (1995), Stewart and
Kantrud (1972), and Kantrud et al. (1989). Sample
size is low for most wetland plant associations, but
a provisional description is presented based on the
literature. The reader is referred to schematic
diagrams in the latter two references for visualizing
the patterns of plant association distribution within
and between wetlands, and the natural dynamics
over time. Undescribed wetland types are presented
separately at the end.

CarescatherodesH erbaceous Vegetation

Awned Sedge H erbaceous Vegetation
Global rank: G3G5; State rank: S?

Summary: The awned sedge wet meadow occurs
in the northern tallgrass and mixed grass prairie
regions of the United States and Canada. Stands
occur on lowland sites that are seasonally
innundated for several weeks each year. These sites
are typically in depressions or basins but can be
along streams and rivers. The water may be fresh or
moderately saline. Soils can be mineral but mucks
often form through the buildup of organic material.
Vegetation cover is usually high but can vary
between wet or dry years. Dominant species are

herbaceous and typically between 0.5 and 1 m tall.
Forb diversity is moderate to high. Carex atherodes
may form essentially monotypic stands or just be
the dominant species. Commonly associated
species include Americn waterplaintain {Alisma
triviale), panicled aster (Aster
lanceolatus ),common spike-rush (Eleocharis
palustris), American mannagrass {Glyceria
grandis), wild mint {Mentha arvensis), reed
canarygrass {Phalaris arundinacea), water
smartweed {Polygonum amphibium), sprangletop
(Scolochloafestucacea),hemlockwa.teY-par&ley
{Slum suave), and small bur-reed {Sparganium
eurycarpum).

The awned sedge plant association is a common
wetland plant association in the prairie provinces
(Looman 1982, Riparian and Wetland Research
Program 2000 ) as well as in the Missouri Coteau
prairie potholes of Sheridan County, generally
found in wetlands of less than 1-2 acres (Lesica
1987b.)

Comments: It was once a common source of
"slough hay" (Looman 1982).

Carex lanuginosa - Calamagrostisstricta
H erbaceous Vegetation

Woolly Sedge- Narrow-spiked Reedgrass
H erbaceous Vegetation

Global rank: G3?; State rank: S?

Summary: The wooly sedge - narrow- spiked
reedgrass herbaceous vegetation is found in the
northern Great Plains. Stands occur on level ground
in shallow depressions and other lowlands on
poorly drained sandy, loamy, or silty clay soils.
Standing water may be present for a few to several
weeks during most years. Soil pH is circumneutral
to somewhat alkaline, and organic content can be
moderately high. The vegetation of this community
provides approximately 100 percent graminoid
cover, typically 0.3-0.6 m tall. Forb cover and
diversity is low.

It is occasional in Missouri Coteau prairie potholes
of Sheridan County. It appears to be situated in
flow-through hydrological positions, with other
wetlands situated both higher and lower in the
watershed.

E-10

CarexpraegracilisH erbaceous Vegetation

Clustered Field Sedge H erbaceous
Vegetation

Global rank: G3; State rank: S?

Summary: The clustered field sedge herbaceous
vegetation is a wet meadow plant association of the
Great Plains. The species is characterized as the
only abundant native graminoid of "fresh" water
conditions in the wet meadow zone of prairie
pothole region (Stewart and Kantrud 1972),
diminishing with increasing alkalinity. Using this
information as inference, it is to be expected as the
least-alkaline wet meadow plant association of
shallow wetlands and the outer zones around
deeper wetlands; sometimes associated with
springs and seeps.

Vegetation: This plant association has 50-90%
cover of Carex praegracilis, and typically occurs
over limited area corresponding with small
wetlands or narrow wetland zones. Other
graminoid species sometimes present include tufted
hairgrass (Deschampsia cespitosa), bearded
wheatgrass (Elymus trachycaulus), meadow barley
(Hordeum brachyantherum), and common arrow-
grass (Triglochin maritimum). Commonly
associated forbs include white-prairie aster (Aster
falcatus) and lance-leaved goldenweed
(Haplopappus lanceolatus).

Environment: The setting is temporarily flooded
early in the growing season. More soils information
is needed. Though most settings are mapped as part
of fine-textured loams, the places where this occurs
on the landscape appear to have porous, well-
drained soils. The soils appeared to accumulate
high organic content in some of the settings. The
presence of halophytes like Triglochin maritimum
and sea-milkwort (Glaux maritima) would seem to
suggest that it is not necessarily restricted to places
with fresh water conditions.

The Medicine Lake area has examples of this plant
association along the Lake Creek valley, where in
one place it was found to cover one side of the
valleybottom. The Missouri Coteau prairie potholes
had few small swales with this type. One of the
more unusual examples was in the Big Muddy
headwaters associated with seeps in the midst of a
wooded slope; noted elsewhere in the Big Muddy
valley margin and coulee bottoms.

Comments: This plant association occupies a zone
that is readily invaded by exotics, and where
livestock use is concentrated. Species that increase
under disturbance in it include Baltic rush

{J uncus balticus), ticklegrass (Agrostis scabra),
fowl bluegrass (Poa palustris), Kentucky bluegrass
(P. pratensis), prairie sagewort (Artemisia
ludoviciana), and common silverweed
(Potentilla anserina). An unusual condition with
extremely high cover of sowthistle (Sonchus spp.)
was also found in the Lake Creek valley.

Carex praegracilis is common in small, intricate
mosaic patterns across sandy flats affected by the
elevated water levels on Lake Creek, where Juncus
balticus, Elymus trachycaulus, and Muhlenbergia
richardsonis are part of the mosaic and the
numbers of associated species are low. The
"natural" vegetation of these settings is unknown.

Distichlisspicata Intermittently Flooded
H erbaceous Vegetation

Saltgrass I ntermittently Flooded H erbaceous
Vegetation

Global rank: G5; State rank: S4

Summary: The saltgrass intermittently flooded
plant association is found in the glaciated northern
Great Plains at small bands and patches associated
with alkali basins, and at isolated alkaline seeps. It
is also found at the base of badlands erosional
sideslopes, in outwash, and in alluvial fan settings
of the unglaciated and thinly-glaciated northern
Great Plains. The soils are moderately to strongly
saline, medium- to fme-textured, and poorly
developed but moderately deep to deep (Hansen
1995, USPS 1992). The water table is high for at
least part of the year and salt encrustations are
often present on the surface. This community has
low species diversity and is dominated by salt-
tolerant graminoids. Total vegetation cover is
sparse to moderate and bareground is common. The
dominant species, Distichlis spicata, comprises 5-
55% canopy cover. Species diversity is low. Other
salt-tolerant species often present include Nuttall's
alkaligrass (Puccinellia nuttalliana),alkali muhly
(Muhlenbergia asperifolia), seablite (Suaeda
calceoliformis) and Nevada bulrush (Scirpus
nevadensis); the latter three particularly in
glaciated settings. Common forbs include white-

E-11

prairie aster {Aster falcatus), slimleaf goosefoot
(Chenopodium leptophyllum), gumweed (Grindelia
squarrosa), slender plantain (Plantago elongata),
indian-wheat {Plantago patagonica), and red
glasswort or samphire (Salicornia rubra).

In Sheridan County, this type is consistently part of
alkali lake landscapes on soils mapped as
ustifluvents, and sometimes present in saline
upwellings along the Big Muddy Creek valley on
Nobe clay.

EI&xharispalustrisH erbaceous
Vegetation

Comnnon Spike-rush H erbaceous Vegetation

Global rank: G5; State rank: S5

Summary: The common spike-rush plant
association occurs in slighty to moderately brackish
wetlands, including prairie potholes and riparian
settings, that are seasonally flooded. It is well-
represented in the central and northern Great
Plains, possibly extending into the Southwest and
the Pacific Northwest states, and is a major type at
low elevations throughout Montana (Hansen 1995).
Species often present include needle spike-rush
(Eleocharis acicularis; often submerged early in
growing season), curly dock (Rumex crispus), and
foxtail barley (Hordeum jubatum).

In Sheridan County, it is found in Missouri Coteau
prairie potholes, and on tributaries of the Big
Muddy Creek in standing water of riparian
channels that become series of small pools by
midsummer, often surrounded by common
threesquare (Scirpus pungens) zones.

Elexharisquinqueflora Marl Fen
H erbaceous Vegetation

Few-flowered Spike- rush M arl Fen
H erbaceous Vegetation

Global rank: Gl?; State rank: SI

Summary: The few-flowered spike-rush/ chara
marl fen herbaceous vegetation is a patterned, rich
fen plant association of the northern Great Plains
found in localized areas where mineral-rich
groundwater flow emerges at the ground's surface.
The dominant or co-dominant species include

Eleocharis quinqueflora, with shallow, open-water
pools dominated by Chara spp., a calciphilic
macroalgae that contributes to calcium carbonate
precipitation. This plant association is documented
from North and South Dakota, and northeastern
Montana, and may be present in adjoining prov-
inces.

Vegetation: This plant association is characterized
by fine-textured short- statured vegetation including
few-flowered spike-rush (Eleocharis quinueflora),
beakrush (Rynchospora capillacea; not known
from Montana), slender muhly (Muhlenbergia
filiformis ),mat muhly (M. richardsonis), Kalm's
lobelia (Lobelia kalmii), and grass-of-parnassus
(Parnassis spp.j (Leoschke 1997). The open marl
pools consistently host Chara, a calciphilic
macroalgae that contributes to calcium carbonate
precipitation. A number of abundant or diagnostic
mosses are present in both mound and pool micro-
habitats. Species that were restricted to or reached
their highest densities in these settings as they
occurred in Sheridan County include: rush aster
(Aster junciformis), green sedge (Carex viridula),
Kalm's lobelia (Lobelia kalmii), Muhlenbergia
filiformis, Torrey's rush (Juncus torreyi), and marsh
arrow-grass (Triglochin palustre).

Environment: This plant association is found
where mineral-rich groundwater flow emerges from
porous, glacial till. These areas remain saturated
throughout the growing season, permitting the
development of organic peat enriched in calcium
carbonate. The intact patterns form parallel mound-
pool (string-flark) microhabitats, with the mounds
dominated or co-dominated by Eleocharis
quinqueflora, and other short- statured graminoids,
and the shallow, open-water pools dominated by
Chara spp. In central and northwestern North
Dakota, these associations are found on slopes
bordering wetlands and along river valley slopes.
These wetland areas remain saturated throughout
the growing season, permitting the development of
organic peat. These associations form parallel
mounds and shallow, interconnected pools, all of
which are composed of marl, a mix of calcium
carbonate, organic matter, and other minerals
(Duxbury 1987, Chadde et al. 1998).

Comments: Under heavy grazing, Triglochin
palustre and T. maritimum increase and under
extreme cases dominate, sometimes in combination
with more robust plants like water sedge (Carex

E-12

aquatilis) and common threesquare (Scirpus
pungens). Then, the parallel mound pattern is
changed into irregularly trampled hummocks, the
pools become eutrophied, and emergent vegetation
becomes established in them.

This plant association requires stable groundwater
discharge, and central pivot irrigation has been
installed near or adjacent to many of the sites since
the 1980s.

This is the habitat of Lobelia kalmii, which appears
to be restricted to Eleocharis quinqueflora plant
associations throughout its range in Montana.

H ordeum jubatum H erbaceous Vegetation

Foxtail Barley H erbaceous Vegetation
Global rank: G4; State rariK: S4

Summary: The foxtail barley herbaceous vegeta-
tion is a seasonally flooded subsaline wetland type
(Thompson 1994), and a drawdown phase of
seasonal and semipermanent brackish and subsaline
marshes. It was noted as common among the
temporary ponds of the Missouri Coteau area of
Sheridan County (Lesica 1987b), a commonness
that was not observed in this study, and which may
have reflected the drought conditions of the time
that the earlier work was conducted.

Comments: Hordeum jubatum is associated with
Distichilis spicata and Pascopyrum smithii, and
becomes abundant to the point of appearing
dominant in these associations when they are under
intense grazing. It has also been noted that Hor-
deum jubatum can dominate on less saline sites
(Redmann 1972) than Distichilis spicata, and is
also a draw-down phase of semi-permanent brack-
ish wetlands under natural conditions (Stewart and
Kantrudl971).

Panicum virgatum - Muhlenberg! a
richardsonis- (Schizachyrium scofxirium)

H erbaceous Vegetation

Switchgrass- M at M uhly- (Little B I uestem)
H erbaceous Vegetation

Global rank: G?; State rank: S?

Summary: The switchgrass - mat muhly - (little
bluestem) herbaceous vegetation is a highly
productive grassland associated with subirrigated
conditions and groundwater discharge as found in
glaciated valleybottom settings, sometimes associ-
ated with springs, seeps, and spring-fed streams. It
is presented in this study as a "new" plant associa-
tion, not recognized on regional plant association
lists to date.

All of the Sheridan County examples are part of
outwash channels, as found in the Medicine Lake
and Missouri Coteau areas. They may be found in
valleybottoms, small isolated "pockets" of habitat
above large alkali wetlands, or meander borders.

Vegetation: The plant association has 100+%
vegetation cover dominated by tall- or mid-height
grasses. There is typically codominance of Pani-
cum virgatum or Muhlenbergia richardsonis, with
or without major cover contributions of
Schizachyrium scoparium. Slender wheatgrass
(Elymus trachycaulus) and tufted hair grass
(Deschampsia cespitosa) are often present. Forbs
commonly found in this setting include dotted
blazing-star (Liatris ligustistylis), meadow
hawksbeard (Crepis runcinata var. glauca), and
lance-leaf goldenweed (Haplopappus lanceolatus).

Environment: This plant association is associated
with glacial outwash valleys and occasionally
found on the seeps of closed-basin alkali lakes
scattered within them. The groundwater is close to
the surface through most of the growing season,
and the fme-textured soils are moderately alkaline
and poorly-drained. Along the Lake Creek valley,
they are mapped as McKenzie silty clay loams.

Comments: This plant association was historically
used for hayland where it covered any extent. But
with the trend in larger machinery and the contin-
ued reduction in area, most of the current examples
are in rangeland. Late-season grazing seems to
have the least affect on it.

Kentucky Bluegrass (Poa pratensis) is often

E-13

present in trace amounts, increasing under heavy
grazing. Early-season grazing can also cause
formation of hummocks and drying of the habitat
under some environmental conditions. Litter
accumulation is high in this plant association type,
and may suppress forb numbers.

This is thought to be the primary habitat for pale-
spiked lobelia (Lobelia spicata) and possibly for
northern blue-eyed grass (Sisyrinchium
septentrionale).

Pascopyrum smithii H erbaceous
Vegetation

Western Wheatgrass H erbaceous Vegetation

Global rank: G3G5Q; State rank: S4

Summary: The western wheatgrass herbaceous
vegetation is a wetland type, even though the
species is also dominant or codominant in many
upland plant associations. This plant association is
found in both temporarily and seasonally flooded
wetlands, and is the most widespread seasonally
flooded wetland plant association in parts of
northeastern Montana, as documented in Thomp-
son (1994). It occurs on fine-textured soils. Cover
of western wheatgrass is high; typically greater
than 70%, and species diversity is low. Characteris-
tic forbs include gumweed (Grindelia squarrosa),
wild lettuce (Lactuca canadensis), horseweed
(Conyza canadensis) and nodding stickseed
(Hackelia deflexa). It is considered to be a minor
component of the mixed grass prairie region in
Saskatchewan (Riparian and Wetland Research
Program 2000).

It is part of riverine systems in Sheridan County,
and is common on clay substrates in poorly-drained
settings along the Big Muddy Creek and tributaries.

Comments: Under disturbance, exotic species
increase, including Japanese brome (Bromus
japonicus), curly dock (Rumex crispus), red sage
(Kochia scoparia), andLoesel's tumblemustard
(Sisymbrium loeselii).

Polygonum amphibium H erbaceous
Vegetation

Water Smartweed H erbaceous Vegetation

Global rank: G3?; State rank: S?

Summary: The water smartweed herbaceous
vegetation is found in seasonally inundated,
slightly brackish wetlands where the basin has been
plowed in the past (Stewart and Kantrud 1971). It
is also found at zones around reservoirs, ponds, and
other wet areas (Hansen 1995). Water smartweed is
a widespread wetland species, but does not appear
to assume dominance in the absence of
perturbations. This plant association is scattered
across northeastern areas of Sheridan County in
settings where part or all of the bottom of the
wetland basin had been plowed at some time in the
past.

POtamogeton pectinatus- Myriophyllum
spicatum H erbaceous Vegetation

Sago Pondweed - Common Water-milfoil
H erbaceous Vegetation

Global rank: G3G4; State rank: SIQ

Summary: Sago pondweed - common water-
milfoil herbaceous vegetation occurs in perma-
nently innundated zones of glacial ponds in gentle,
rolling, glacial terrain. It has been reported from
north-central Montana (Lescia 19X), with similar
or closely-related assocations in western Montana,
North Dakota, and Saskatchewan; also reported
from California. This type occurs in permanent
ponds with mildly brackish water less than about 1
m deep. Submerged species dominate the stands
with low canopy cover (50%). Potamogeton
pectinatus is always present and usually accompa-
nied by Myriophyllum spicatum.ln addition, water
buttercup (Ranunculus aquatilis), common bladder-
wort (Utricularia vulgaris), and Richardson's
pondweed (Potamogeton richardsonii) are com-
monly associated species in some ponds

In Sheridan County, submerged vegetation domi-
nated or co-dominated by sago pondweed is in the
Missouri Coteau wetlands as well as the channel of
the Big Muddy Creek.

Comments: Sago pondweed herbaceous vegetation
comprises the most extensive submerged vegetation
in both riparian and lacustrine wetland settings.

E-14

The species has been characterized as the single
most important food for waterfowl elsewhere in the
Missouri Coteau because of its abundance, and the
nutritional value of both the seeds and the tubers
(Metcalf 1931).

R uppia maritima G reat Plains
H erbaceous Vegetation

Wigeon-grass Great Plains H erbaceous
Vegetation

Global rank: G?; State rank: S?

Pucdneilia nuttalliana H erbaceous
Vegetation

N uttall's Alkali grass H erbaceous Vegetation

Global rank: G3?; State rank: S?

Summary: The Nuttall's alkaligrass herbaceous
vegetation requires seasonally saturated saline soils
as found in wet meadows, saline seeps, and the
margins and flats associated with alkali lakes. It is
found on glaciated and unglaciated areas of the
Great Plains and intermountain region, extending
from Alberta and Saskatchewan to Nebraska, and
west through the intermountain region to Utah and
California. The settings are moisture-collecting
positions that are temporarily or seasonally inun-
dated, maintaining moist soil conditions throughout
most growing seasons, though drying out at the
surface. Species diversity is low and variously
includes saltgrass (Distichilis spiata), foxtail
barley (Hordeum jubatum), alkali bluegrass (Poa
juncifolia; treated by some taxonomists as synony-
mous with Poa secunda), red goosefoot (Chenopo-
dium album), sea blite (Suaeda calcifonnis), and
amaranth (Amaranthus spp.) In eastern Alberta it is
described as a saline emergent marsh or hypersa-
hne dry meadow (Wallis 1990), and it is an inci-
dental component of the mixed grass prairie region
in Saskatchewan (Riparian and Wetland Research
Program 2000).

In Sheridan County, it is found as part of alkali lake
systems and in localized low-lying settings with
salt accumulation, including the Big Muddy Creek
valley and tributaries.

Comments: Nuttall's alkahgrass is generally
considered a decreaser under livestock grazing
(Smith 1976). In Sheridan County, it was found in
conditions ranging from idle to trampled.

Summary: Wigeon grass plant associations are a
submerged vegetation restricted to saline lakes and
some of the associated subsaline wetlands, with a
conductivity normally over 15,000 micromhos/cm3
(Stewart and Kantrud 1971). Many of the settings
are aptly called hypersaline, with higher salinity
than the ocean. They occur in the glaciated plains
regions of Alberta, Saskatchewan, Montana and
North Dakota, typically in closed-basin watersheds,
often part of glacial outwash channels. More
information is needed on cover values and distribu-
tion of the submerged vegetation as affected by
water depth, water chemistry, and wave action.

In Sheridan County, the wigeon-grass plant associa-
tion was found along the large outwash channels
toward the eastern end of the county in brackish
wetlands.

Comments: The plant association has direct
wildlife value in that wigeon-grass has been
characterized as one of three major foods for
waterfowl elsewhere in the Missouri Coteau
(Metcalf 1931).

Salicorn'ia rubra H erbaceous Vegetation

Red Glasswort (Samphire) H erbaceous
Vegetation

Global rank: G3G4; State rank: S2?

Summary: The red glasswort herbaceous vegeta-
tion is found on the shores of saline semipermanent
ponds and lakes (Stewart and Kantrud 1971) and
associated alkali flats during the dry or draw-down
phase. It is mainly in the prairie pothole region,
with reports of similar associations in Colorado and
Nevada. Soils are subsaline or saline, gleyed, with
generally fine textures ranging from silt loam to
clay (Looman 1981). It occupies the seasonal
drawdown areas that are generally too wet for
saltgrass (Distichilis spicata). Vegetation is typi-
cally sparse and patchy, with Salicornia rubra
sometimes making up all of the vegetation within
these areas, with or without Nuttall's alkaligrass

E-15

(Puccinellia nuttalliana), foxtail barley (Hordeum
jubatum), common arrow-grass (Triglochin
maritimum), red goosefoot (Chenopodium rubrum),
and sea blite (Suaeda calceolifonnis). This plant
association is among the few dominated by an
annual species; making major shifts in cover
between drought and high- water conditions, but
generally a persisting feature.

In Sheridan County, there were vast expanses of
red glasswort south of Salt Lake under the some-
what dry conditions of 1998 that were innundated
and part of a sparse alkali bulrush (Scirpus
maritimus) wetland under closer-to-normal water
levels in 1999. It is recognized in this vegetation
classification primarily as a persisting component
of the alkali lake system, rather than as an ephem-
eral drought-response phenomenon.

SdrpusacutusH erbaceous Vegetation

H ardstem Bulrush H erbaceous Vegetation
Global rank: G5; State rank: S5

Summary: The hardstem bulrush herbaceous
vegetation is among the most common plant
associations of semipermanently flooded wetlands
in parts of northeastern Montana (Thompson 1994)
and at low elevations throughout Montana (Hansen
et al. 1995). It dominates in wetlands with water
chemistry conditions that are mildly- to moder-
ately-brackish (Stewart and Kantrud 1972). The
tall emergent vegetation is 1-2 m tall, and varies
greatly in density with annual changes in water
levels and muskrat activity.

In Sheridan County, it is particularly extensive
around Lake Creek, including areas of Medicine
Lake NWR with artificially maintained water
levels. It is also dominant in many of the larger
prairie potholes.

SdrpusmaritimusH erbaceous Vegetation

Alkali Bulrush H erbaceous Vegetation
Global rank: G4: State rank: S4

Summary: Plant associations dominated by alkali
bulrush are common in brackish and subsaline
semipermanently flooded wetlands, and to a lesser
extent, perennial streams. They are characteristic of

saline emergent marsh in the provinces (Looman
1981, Wallis 1990) and have been recognized
elsewhere in northeastern Montana (Thompson
1994). The alkali bulrush plant association is often
an emergent band around open water with sub-
merged vegetation of Potamogeton pectinatus or
Ruppia maritima. It also occurs as zonal vegetation
around other plant associations. The cover of alkali
bulrush may almost disappear in openwater condi-
tions of wet years, or be replaced by red glasswort
(Salicornia rubra) in drought years.

In Sheridan County, it is mainly in the Missouri
Coteau prairie pothole area where there are glacial
meltwater channels. Many but not all wetlands
dominated by alkali bulrush are part of alkali lake
landscapes.

Comments: Alkali bulrush has been characterized
as one of three major foods for waterfowl else-
where in the Missouri Coteau (Metcalf 1931).

ScirpuspungensH erbaceous Vegetation

Common Threesquare H erbaceous
Vegetation

Global rank: G3G4; State rank: S3

Summary: The common threesquare herbaceous
vegetation is found along low-gradient, usually
perennial streams and around the margins of
semipermanently-flooded ponds and marshes in the
Intermountain Basin and the western and northern
Great Plains (Hansen et al. 1995, Jones and
Walford 1995, Stewart and Kantrud 1972).
Characteristically, it is a "zonal" vegetation
restricted to bands rather than occurring throughout
basins of suitable depth. It is typically in shallow,
brackish water, in settings where salt often
precipitates when water levels drop. Scirpus
pungens dominates the herbaceous vegetation
layer, which is 1 foot to 2 feet tall; other graminoid
species may be present are alkali cordgrass
(Spartina gracilis), foxtail barley (Hordeum
jubatum), western wheatgrass (Pascopyrum
smithii), and common spike-rush (Eleocharis
palustris). Forb species are few. Note: This
includes plant associations previously referred to as
having dominance by Scirpus americanus Olney
(Stewart and Kantrud 1972, and Looman 1981)
citing the taxonomic treatment that is recognized as
a synonym with S. pungens (Great Plains Flora
Committee 1986).

E-16

The sharp bulrush plant association occurs in a
wide variety of Sheridan County settings, though it
is nowhere extensive. It is an outer zone around
many shallow and deep brackish wetlands, and
often the only emergent vegetation on alkali lakes,
in broken shoreline segments marking groundwater
discharge. It is similarly referred to as saline
emergent marsh in eastern Alberta (Walhs 1990). It
is also in seasonally or semipermanently-flowing
tributaries of the Big Muddy Creek.

Scolochloa festucacea H erbaceous
Vegetation

Sprangletop (Whitetop) H erbaceous
Vegetation

Global rank: G4G5; State rank: S?

Summary: The sprangletop herbaceous vegetation
is found in the northern Great Plains, including
North Dakota, Montana, Manitoba and
Saskatchewan. Stands occur in seasonally- and
semipermanently flooded sites with water 0.3-1 m
deep. Stands dominated by Scolochloa festucacea
are usually slightly to moderately brackish
(Looman 1981, 1982, Stewart and Kantrud 1972).
Graminoids 1.0-2.0 m tall dominate the moderately
dense to dense vegetation cover. Scolochloa
festucacea is the single most abundant species and
may occur in almost monotypic stands. Other
species sometimes present include awned sedge
(Carex atherodes), common spike-rush (Eleocharis
palustris), American mannagrass (Glyceria
grandis), hemlock water-parsley {Sium suave), star
duckweed (Lemna trisulcata) and common
bladderwort (Utricularia vulgaris).

The sloughs dominated by sprangletop were once
exceedingly abundant in northern North Dakota
(Metcalf 1931), and Metcalf called these same
sloughs "mallard sloughs." The seeds of
sprangletop were sought by waterfowl, and the
sloughs were most frequented by them. Few
examples of this type have been noted in Sheridan
County, restricted to the Missouri Coteau prairie
potholes area.

Triglochin maritimum H erbaceous
Vegetation

C ommon Arrow-grass H erbaceous
Vegetation

Global rank: GU ; State rank: S?

Summary: Common arrow-grass herbaceous
vegetation is provisionally described as a saline
wetland vegetation that may occur in the absence
of disturbance, but definitely occurs under heavy
livestock grazing. It is present on fine-textured soils
of saline and subsaline lakes, seeps, and associated
inlets. Vegetation is dominated by common arrow-
grass often intermixed with Nuttall's alkaligrass
(Puccinnellia nuttalliana) and alkali bulrush
(Scirpus maritimus). It corresponds with the saline
emergent marsh of eastern Alberta (Walhs 1990).

In Sheridan County, the most extensive stand of
this plant association was found on a large wetland
basin that no longer holds water in the summer. It
has not routinely been considered a drawdown
species, and the setting may represent a site where
the water table has been lowered. It occurs
naturally in narrow bands as part of the alkali lake
system, sometimes forming 100% canopy cover
along inlets. It was also dominant at alkaline seeps
in the Big Muddy valley under heavy grazing
pressure.

Typha latifdia Western IH erbaceous
Vegetation

Common Cattail Western H erbaceous
Vegetation

Global rank: G5; State rank: S5

Summary: The common cattail western
herbaceous association is found throughout the
Northern Great Plains. Stands occur in semi-
permanent wetlands, as well as in stock ponds, and
seepy drainages. The vegetation is dominated by
relatively pure stands of Typha spp., including
Typha latifolia, lesser cattail (Typha angustifolia),
or hybrids between the two. Dominance by T
latifolia occurs in fresh and slightly brackish
conditions. Dominance by T angustifolia occurs
under more alkaline conditions. The hybrid occurs
in roadside ditches and borrow pits, as well as
natural wetlands where the water levels vary
greatly. The Typha latifolia wetland plant

E-17

association is considered to be a major component
of the mixed grass prairie region in Saskatchewan
(Riparian and Wetland Research Program 2000)

The common cattail plant association is uncommon
in Sheridan County. The only large stand noted
was in nearby Homestead Lake NWR. A narrow-
leaf cattail thought to correspond with the hybrid is
also present. Elsewhere in the county, a narrow-leaf
cattail was noted in distinct bands around alkaline
springs, thought to be T. angustifolia.

Wetland Types U nder
Review

The following wetland plant associations were
noted from no more than two plots or observations,
and they do not mesh with plant associations
described for immediately adjoining areas of the
plains. They are treated as provisional, warranting
expanded field investigation and further
consideration.

Plains. Stands typically occur in depressions or
around ponds or lakes, although they may also
develop adjacent to streams or rivers. The sites on
which it develops are flooded for some time during
the growing season in most years and have fresh or
slightly saline water. The Canadian literature
reports that this association is found mainly on
mineral soils (Looman 1981, 1982), while the
montane form of this association is found mainly
on organic soils (Hansen et al. 1995) as were the
limited examples found in Sheridan County. The
vegetation is dominated by graminoids
approximately 0.4 to 0.7 m tall. Carex spp.
predominate, especially Carex aquatilis, as well as
beaked sedge (Carex utriculata), lake sedge
(Carex lacustris), and tussock sedge (Carex stricta)
in parts of its range. Note: The latter two are
uncommon in Montana, and the Carex utricultata
is in the state as a montane wetland plant
association. Other species found in this community
include common spike-rush (Eleocharis palustris),
bullrushes (Scirpus spp.), and cattails (Typha spp.)
Typical forbs include rough bugleweed (Lycopus
asper), western dock (Rumex occidentalis), and
hemlock water-parsley (Sium suave).

CalamagroEtisstricta H erbaceous
Vegetation

N arrow-spiked Reedgrass H erbaceous
Vegetation

Summary: Narrow-spiked reedgrass is an
occasional-to-common species in wet meadows of
Sheridan County, and was a localized dominant on
seeps along the Lake Creek Valley, with 90% cover
of Calamagrostis stricta and 10% cover of woolly
sedge (Carex lanuginosa). It adjoined the Carex
praegracilis plant association and the Eleocharis
quinqueflora I Chara spp. plant association.
Further vegetation sampling is needed to determine
whether this is a repeating plant association on the
landscape.

Carex aquatilisG reat Plains H erbaceous
Vegetation

Water Sedge H erbaceous Vegetation

Summary: The water sedge herbaceous vegetation
of the Prairie Region is found in the northern Great

In Sheridan County, this is a minor plant
association that occurs as small patches where
there is groundwater discharge or springs along
wetland borders. Most places where it occurs are in
outwash channels. It is found in small isolated
pockets or outer margins of peatland habitat as the
only peatland habitat, or enircling the few-flowered
spike-rush plant association (Eleocharis
quinqueflora).

ElymustrachycaulusH erbaceous
Vegetation

Bearded Wheatgrass H erbaceous Vegetation

Summary: Thick- spike wheatgrass appeared to
dominate a wet meadow area in the Lake Creek
Valley, comprising app. 70% cover. Other grasses
that were respresented by more than 1% cover
included Muhlenbergia richardsonis and Panicum
virgatum. The most abundant forb was Helianthus
nuttallii. Further vegetation sampling is needed to
determine whether this is a repeating plant
association on the landscape.

E-18

E lymustrachycaulus- D istichilisspicata
H erbaceous Vegetation

Bearded Wheatgrass - Saltgrass H erbaceous
Vegetation

Summary: The bearded wheatgrass - sahgrass
Herbaceous Vegetation appears to be a wet
meadow plant association associated with alkali
lakes. It is restricted to soils with high clay content,
frequently found on points or penninsulas along the
shoreline. It lies within the broad zones mapped as
saline ustifluvent soil.

E lymustrachycaulus- Spartina gradlis
H erbaceous Vegetation

Bearded Wheatgrass- Alkali Cord grass
H erbaceous Vegetation

Summary: An association dominated by bearded
wheatgrass and alkali cordgrass was documented in
temporarily inundated wet meadow on clay soils
among a series of wetlands associated with an
alkali lake. Further vegetation sampling is needed
to determine whether this is a repeating plant
association on the landscape.

Panicum virgatum - Spartina pectinata
H erbaceous Vegetation

Switchgrass - Prairie Cordgrass H erbaceous
Vegetation

Summary: An association codominated by
switchgrass and prairie cordgrass was documented
in a spring-fed tributary of the Big Muddy Creek.
The latter generally occupies wetter habitat, and it
is possible that their co-dominance is more
appropriately treated as an ecotone between
separate switchgrass and prairie cordgrass plant
associations.

Sdrpusne^adenssH erbaceous Vegetation

Nevada Bulrush H erbaceous Vegetation

Summary: The Nevada Bulrush herbaceous
vegetation is characterized as typical of sandy
saline shores of eastern Alberta (WalHs 1990). It is
at best a very broad and long vegetation zone like
Scirpus pungens. The largest area of it was less

than 1 acre, noted on a saline seep along the Lake
Creek Valley, and noted elsewhere on Medicine
Lake NWR, Brush Lake area, and Goose Lake.

Spartina gracilisH erbaceous Vegetation

Alkali Cordgrass H erbaceous Vegetation

Summary: Alkali cordgrass is dominant in narrow
zones and patches with high cover values. It
formed discrete bands around alkaline springs, and
included such species as foxtail barley (Hordeum
jubatum), rush aster (Aster junciformis) and sea-
milkwort (Glaux maritima). Further vegetation
sampling is needed to evaluate this as a minor plant
association.

Spartina pectinata H erbaceous
Vegetation

Prairie Cordgrass H erbaceous Vegetation

Summary: The prairie cordgrass herbaceous
vegetation is typically found in slightly or
moderately brackish wetlands that are temporarily
or seasonally inundated. It is treated by Hansen et
al. (1995) as similar with regards to environment
and management as plant communities dominated
by Spartina gracilis, and the collective cordgrass
associations are characterized as extending into
saline conditions. Most plant association
descriptions are from unglaciated portions of the
Great Plains, from drainage bottoms where the soil
is wet for at least part of the growing season, or in
poorly drained depressions within floodplains of
major rivers. In the glaciated plains, it is often
associated with groundwater discharge in riverine
systems forming seasonally-inundated wet
meadow; and occasionally in temporarily or
seasonally flooded wetlands. Further vegetation
sampling and review of existing plant associations
dominated by Spartina pectinata is needed for
classification purposes.

In Sheridan County, it was found in an upper reach
of the Lake Creek valley where Spartina pectinata
was sole dominant.

Comments: It is a highly productive grassland
found in a narrow range of conditions, readily
altered by grazing and any on- site/off- site changes
to water conditions.

E-19

Shrubland Types

Shrublands are widely scattered in Slieridan
County but are not extensive. They are variously
referred to as thickets, scrub, and steppe. We have
included grassland and sparse vegetation types here
in which shrubs have a strong presence but have
less than 25% canopy cover. Stands with this
structure and composition have a unique
designation in the classification at the formation
level.

A rtemisa cana I Pascopyrum snithii
Shrubland

Silver sagebrush - Western Wheatgrass
Shrubland

Global rank: G4: State rank: S4

Summary: The silver sagebrush - western
wheatgrass shrubland is found mainly in the
western Great Plains on flat alluvial deposits on
floodplains, terraces or benches, and alluvial fans.
The soils are moderately deep to deep and either
silt loam, clay loam, or sandy loam. Flooding may
occur periodically and this tends to retard soil
development. This community is dominated by a
combination of shrubs and graminoids. The total
vegetation cover is moderate. The tallest and most
conspicuous stratum in this community is a shrub
layer that is usually 0.6-1.2 m. dominated by
Artemisia cana. Grass cover is dominated by
Pascopyrum smithii and typical forbs of this
community are yarrow (Achillea millefolium),
scarlet gaura (Gaura coccinea), red globe-mallow
(Sphaeralcea coccinea), and blue lettuce (Lactuca
pulchella).

This plant association is uncommon in glaciated
landscapes, and was only noted in Sheridan County
along an isolated area of Wolf Creek, and Beaver
Creek in the Big Muddy headwaters. While this
plant association is not restricted to riparian
settings, those observed fit the wetland
characterization for it as presented in Hansen et al.
(1995). In Sheridan County, Artemisia cana
comprised canopy cover which was usually less
than 25%, more appropriately referred to as shrub
herbaceous vegetation.

Elaeagnuscommutata Shrubland

Silverberry Shrubland
Global rank: G2Q; State rank: S2?

Summary: Silverberry shrubland is reported in
northern Montana east of the Continental Divide,
and generally classified as temporarily flooded. A
related association with an understory of
Pascopyrum smithii is reported from Hill County,
provisionally representing the "typical" floodplain
type. The validity, composition, and status of
silverberry shrublands needs documentation and
further evaluation, including more information on
the floodplain stands from Saskatchewan, and more
information on upland stands to the east.

Small pockets of Elaeagnus commutata plant
assocation with a needle-and-thread (Stipa comata)
understory are present in the Medicine Lake
sandhills of Sheridan County, with shrub canopy
cover of over 10% and grass canopy cover over
70%. It is not flooded, but the water table is within
rooting zone. The species is also common on a few
of the north-facing northern porcupinegrass (Stipa
curtiseta) slopes in the county that have high levels
of litter accumulation, and may be on the increase
in such settings.

Eriogonum paudflorum - Gutierrezia
ssrot/Trae Badlands Sparse Vegetation

Few-flowered Wild Buckwheat - Broom
Snakeweed Badlands Sparse Vegetation

Global rank: G?; State rank: S?

Summary: The few-flowered wild buckwheat -
broom snakeweed Badlands sparse vegetation
represents an outcrop or scabland feature of the
northern Great Plains in Montana, North Dakota
and South Dakota. It occurs on unconsolidated or
poorly-consolidated sedimentary formations that
are easily eroded, including siltstones, mudstones,
and shales. Slopes that become stabilized
revegetate to grassland with succession.

This badlands plant association type rarely exceeds
10% vegetative cover and is often less than 5%,
hence it is technically placed in a sparse vegetation
classification category rather than a grassland plant
association. On level terrain, the vegetation is
relatively evenly distributed, but on steeper slopes

E-20

and cliffs the vegetation may grow in patches and
in rows or seams. Plant species that are nearly
always present include few-flowered buckwheat
(Eriogonum pauciflorum), broom snakeweed
(Gutierrezia sarothrae), plains pricklypear
(Opuntia polyacantha) , common rabbitbrush
(Chrysothamnus nauseosus), silverscale (Atriplex
argentea), a cryptantha (Cryptantha thyrsifolia, a
characteristic plant at least in South Dakota), and
the forb gumweed (Grindelia squarwsa). In
Sheridan County, it is restricted to the most
exposed and rugged breaks of the Big Muddy
valley and major tributaries cutting into bedrock. It
encompasses the "Chrysothamnus nauseosus /
Eriogonum pauciflorum plant association type"
previously described in southeastern Montana
where sparse Badlands vegetation is more common
(Cooper and Heidel 1998).

Comments: Few-flowered wild buckwheat is
considered to be a "sub-shrub", thus, the plant
association is included among shrub-dominated
plant associations.

Prunusvirginiana Shrubland

Common Chokecherry Shrubland
Global rank: G4Q; State rank: S4

Sarcobatusvermiculatus/ Pascopyrum
anithii Shrub H erbaceous Vegetation

Black Greasewood / Western Wheatgrass
Shrub H erbaceous Vegetation

Global rank: G4; State rank: S4

Summary: The black greasewood / western
wheatgrass shrub herbaceous vegetation is found in
the northwestern Great Plains on flat to gently
sloping alluvial fans, terraces, lakebeds, and
floodplains. The soil is usually deep clay, silty clay,
sandy clay, or loam although coarse soils are
possible. They are saline or alkaline but salt crusts
on the surface are absent. Parent material is usually
alluvium. This community has moderate to dense
vegetation cover. Medium tall (0.5-1.5 m) shrubs
are scattered throughout with a total shrub canopy
of 5-25 percent, dominated by Sarcobatus
vermiculatus. Few forbs are found in this
community, and yarrow (Achillea millefolium) and
plains pricklypear (Opuntia polyacantha) are the
only species with high constancy.

In Sheridan County, it is present in salt-affected
flats with Nobe clay substrate along the Big Muddy
Creek, corresponding with the saline lowland range
site. It is a major type elsewhere in eastern and
central Montana (Hansen et al. 1995).

Summary: This was provisionally treated as two
separate sandhills plant associations, the Prunus
virginiana/ Stipa comata Shrubland and the Prunus
virginiana/ Agropyron caninum (Elymus
trachycaulus) Shrubland by Lesica (1987a). In this
study, all occurrences noted were smaller than the
sample plot size, having high shrub cover and very
low understory cover. Heavy browsing and levels
of disease were noted. More complete
characterization of this as vegetation is needed. It is
generally considered a successional phase of the
green ash- or box elder-dominated Woodlands
(Fraxinus pensylvanica or Acer negundo
Woodland) in eastern Montana (Hansen et al.
1995).

Prunus virginiana has a deep root system that can
reach the sandhills water table. Elsewhere in
northeastern Montana, it forms a riparian corridor
plant association, classified as a seasonally flooded
wetland (Thompson 1994).

Shepherdia argentea Shrubland

Buffaloberry Shrubland
Global rank: G3G4; State rank: S3?

Summary: The buffaloberry shrubland is a mesic
shrubland plant association found in the northern
Great Plains from North Dakota and Saskatchewan
to Colorado on stream terraces, rolling uplands,
and badlands. It occurs where moisture is more
plentiful than on the surrounding landscape, such
as in swales, ravines, near streams, and on
northwest- to east-facing slopes. This plant
association is dominated by a moderate to dense
canopy of medium-tall shrubs. The most abundant
of these, Shepherdia argentea, is typically 1.5-3 m
tall. Other common shrub species are common
chokecherry (Prunus virginiana), skunkbush sumac
(Rhus aromatica). Wood's rose (Rosa woodsii),
and western snowberry (Symphoricarpos
occidentalis). Graminoids and forbs may have only
half the coverage of the shrub layer. Graminoids

E-21

include western wheatgrass (Pascopyrum smithi),
and invasion by Kentucky bluegrass (Poa
pratensis). Common forbs are yarrow {Achillea
millefolium), prairie sagewort {Artemisia
ludoviciana), and common pellitory {Parietaria
pennsylvanica).

The Shepherdia argentea plant association is not
common in Sheridan County. Well-developed and
extensive stands were noted along a deeply-incised
segment of Eagle Creek in the Big Muddy
headwaters. Elsewhere in its distribution, most
stands to the south and east along the Missouri
River are on sheltered upland prairie slopes, while
most of the stands to the west are similarly in
riparian settings, and classified as seasonally
flooded wetland (e.g., Thompson 1994).

Symphor/carpQ50CC/der7td//s Shrubland

Western Snowberry Shrubland
Global rank: G4G5; State rank: S4S5

Summary: The western snowberry shrubland is
found in mesic depressions, swales, ravines and
floodplains, typically surrounded by upland
grassland associations. The soils are silts and
loams. This type has a shrub layer (app. 80 cm tall)
with high canopy cover, sometimes with well-
developed graminoid- and forb-layers.
Symphoricarpos occidentalis is the predominant
species in the shrub layer and at times forms almost
monospecific stands. Rosa woodsii sometimes
occurs interspersed with the Symphoricarpos
occidentalis. Some stands are occasionally flooded
whereas others are just very moist. Thus it tends to
fall on both sides of the upland/wetland division. It
has been classified in both temporarily and
seasonally flooded wetland classes elsewhere in
northeastern Montana, where it is among the most
extensive of temporarily flooded wetland plant
associations (Thompson 1994).

It is present throughout Sheridan County, including
shallow prairie potholes, valley margins, and
widely scattered elsewhere. It may accompany
invasion of Kentucky bluegrass {Poa pratensis).

Comments: It corresponds with the

Symphoricarpos occidentalis - Rosa woodsii

association encroaching on sandhill flats and
swales (Lesica 1987a). The same type was found in
the Missouri Coteau prairie potholes in concave
areas of lee slopes where snow accumulates
(Lesica 1987b). It is also recognized as a major
component of the mixed grass prairie region in
Saskatchewan (Riparian and Wetland Research
Program 2000).

Shrubland Types U nder
Review

J uniperushorizontalis/ E lymuslanceolatus

Shrublana

Creeping Juniper/ Thick-spike Wheatgrass
Shrubland

Summary: Stands dominated by creeping juniper
in association with thick-spike wheatgrass were
documented in the Big Muddy headwaters on
sheltered, north-facing slopes on silt loam derived
from shale or other fme-textured parent material.
This vegetation is reported elsewhere in
northeastern Montana where it is more extensive,
and it will be described separately in a separate
document with larger sampling sets. Shrub cover is
well over 50%, with Juniperus horizontalis
comprising almost all of the shrub cover and
shrubby cinquefoil {Pentaphylloides floribunda)
usually present. Species diversity is high,
especially for forbs, and they include northern
hedysarum {Hedysarum boreale), old man's
whiskers (Geum triflorum), slender crazyweed
{Oxytropis campestris), harebell (Campanula
rotundifolia), pasqueflower {Anemone patens), and
tufted fleabane {Erigeron cespitosus).

Pentaphylloidesfloribuncia/ Stipa curtiseta
Shrubland

Shrubby Cinquefoil / Northern
Porcupinegrass Shrubland

Summary: One stand dominated by shrubby
cinquefoil in association with northern
porcupinegrass was documented along the Big
Muddy headwaters, on a sheltered, north-facing
ravine slope. It has over 35% cover of shrubby

E-22

cinquefoil, comprising almost all of the shrub
cover, with shrub height approaching 3 ft. The
cover of Carex inops at app. 20% is almost as much
as the graminoid cover oiStipa curtiseta. Forb
diversity is high and northern bedstraw {Galium
boreale) is especially abundant, approaching 20%
cover, followed by northern hedysarum
(Hedysarum boreale) and old man's whiskers
(Geum triflorum). This provisional plant
association does not appear to correspond with
shrubby cinquefoil plant associations in the
provinces, and is recommended for consideration
as part of future vegetation ecology studies in
northeastern Montana or southwestern
Saskatchewan.

Sarcobatusvermiculatus/ D istichlisspicata
- (PucdnnelUa nuttalliana) Saline Shrub

Sparse Vegetation

Black G reasewood / Saltgrass -(Nuttall's
Alkaligrass) Saline Shrub Sparse Vegetation

Summary: Stands dominated by black greasewood
in association with saltgrass or Nuttall's alkaligrass
were recorded at several alkali lakes on their
leeward shores. These lakes dry out periodically,
and salt deposits from the lakebed are carried by
the wind and redeposited onshore (Dodd and
Coupland 1961). Soils are ustifluvents. Shrub cover
is comprised entirely of Sarcobatus vermiculatus,
app. 10-20%, and usually stunted (less than 2 ft
tall). Graminoid cover is low at 10-40%. Species
diversity is low, and limited to halophytes like
common arrow-grass (Triglochin maritimum).

Woodland Types

Woodlands are defined as "open stands of trees
with crowns not usually touching, generally
forming 25-60% cover" (Grossman et al. 1998).
They are present in small bands and pockets as
dictated by the topography of ravines and
escarpments. This topographic relief is conducive
to moisture-concentration without salt
accumulation, and provides a natural firebreak
condition.

Fraxinuspenns^vanica / Prunus
virgin! ana W oodland

G reen Ash / C hokecherry Forest

Global rank: G3?; State rank: S2S3

Summary: The Fraxinus pennsylvanica / Prunus
virginiana Woodland represents islands of
deciduous tree cover on the plains, known from the
north- and central- Great Plains states. It is
confined to sheltered topographic settings, often
where moisture collects. The typical setting is
found in ravines along the breaklands of major
river courses, but also developed on escarpment
slopes and a riparian climax vegetation following
Populus deltoides in areas with sufficient moisture.
Stands that occur in wooded ravines are often
classified as temporarily flooded wetlands, and
floodplain stands (not observed in Sheridan
County) as seasonally flooded wetlands; both of
which are documented and classified as such
elsewhere in northeastern Montana (Thompson
1994). The herbaceous vegetation is typically
dominated by Sprengel's sedge (Carex sprengelii).
Other species present include serviceberry
(Amelanchier alnifolia), western snowberry
(Symphoricarpos occidentalis), Virginia wildrye
(Elymus virginicus), false starry Solomen's-seal
(Smilacina stellata), and Wood's rose (Rosa
woodsii).

It is the only major woodland type in the county, of
very limited extent in sheltered ravines along the
Big Muddy Valley and tributaries, and widely-
scattered on upland escarpment slopes on Lambert-
Zahill complex, 20-50%. It represents the typical
woody draw plant association of eastern Montana.
The settings are relatively dry and the tree stature

E-23

particularly short in the driest upland escarpments
(less than 20 ft), though the stands have a well-
developed woodland understory that includes
species not present elsewhere in the county.

Comments: Woody draws are recognized for
wildlife values (Severson and Boldt 1977), and are
potentially vulnerable in Montana (Lesica 1987c).
Kentucky bluegrass {Poa pratensis) increases with
intensity of livestock use, and impedes tree
seedling establishment. Some ravines along the Big
Muddy valley are heavily invaded by leafy spurge
{Euphorbia esula).

Populustremuloides/ Symphoricarposalbus
Forest

Quaking Aspen / Common Snowberry
Forest

Global rank: G3?; State rank: S3?

Woodland Type U nder
Review

C rataeguschrysocarpa Woodland

Yellow-fruit H awthorn Woodland

Summary: The yellow-fruit hawthorn woodland is
a small plant association in the bottom of draws. It
is reported from Saskatchewan (Riparian and
Wetland Research Program 2000) and Alberta
(Allen pers. comm.), including the Cypress Hills
escarpment and other landforms with ravines. In
Sheridan County it was found north of Raymond in
side-draws along a deep glacial meltwater channel.
The limited survey did not turn up examples with
native species understory.

Summary: The quaking aspen/ common
snowberry forest is provisionally applied to small
stands of quaking aspen in the most sheltered
ravine segments that drain north into the Big
Muddy Creek. They harbor boreal species present
and not otherwise occurring in the county including
red raspberry (Rubus idaeus), baneberry (Actaea
rubra), fairybell (Disporum trachycarpum), and
striped coral-root (Corallorhiza striata). The only
stands that were visited had relatively tall (>30 ft)
tree canopy. Small, young groves of Populus
tremuloides are also present in the sandhills, but
did not have a native understory, and their growth
and expansion was kept in check by grazing.

E-24

Appendix F. Characteristic plant associations of Sheridan County

MedicLDcLake sHndbilt

pnmusyirginiana
\

O?y£opsis hymertoides - - Psoralidium Icatceolatum

Siipacomata-
Pso^aiidium lanceolatum

Pascopyrvm smUhii - \

\
Missouri Coleau collapsed moraine

Efymus (wiceoiatm -
(Koeleria macranlha)

Pffscfipyram smiihii -^ Stipa contaTfi^

^ Stipa cjffiiseta

Intefmediate conditionst

Elynms iancsoitiiui - Stipa comsta

Bi|g Mvddj' vulley

S &

Pascopyrum smUhii - Stipa comata

Pascopyntm smUhii- Stipa comata-

Botiteloua gfocUis \

Stipa comata - Souteiima gfociik

Fascopyrwn stitithii - Stipa comtUa -
Bouifiloua gracilis \

Eiymvs la/tceohtas - Stipa comata
Pmcopyrum smithij ■- Bouteioua gracilis
Artemisia ctma \ Pascopyrum smithii

F-l

Appendix G. -Draft- Range Sites, Ecological Units* And Plant Associations** Of Sheridan County

Northern Dark Brown Glaciated Plains (S3 A); 10-14" precip. zone

Range Site

Big Muddy Headwaters

Medicine Lake Area

Missouri Coteau Prairie Pothole

Subirrigated

Panicum virgatum - Muhlenbergia richardsonis-

(Schizachyrium scoparium)

Carex praegracilis

Spartina pectinata.

Panicum virgatum - Muhlenbergia
richardsonis - (Schizachyrium scoparium)
Carex praegracilis

Sarcobatus vermiculatus/Distichilis spicata

Distichilis spicata

Pascopyrum smithii

Pascopyrum smithii-Hordeum jubatum

Elymus trachycaulus-Distichilis spicata

Saline
Lowland

Sarcobatus vermiculatus/Pascopyrum
smithii

Distichilis spicata
Triglochin maritimum

Distichilis spicata
Puccinnellia nuttalliana

Overflow

Artemisia cana/Pascopyrum smithii
Pascopyrum smithii - Nasella viridula

Pascopyrum smithii - Nasella viridula

Oryzopsis hymenoides - Psoralidium

lanceolatum

Slipa comala - Psoralidium lanceolatum

Calamovilfa longifolia - Stipa comata

Stipa comata - Bouteloua gracilis - Carex

filifolia

Pascopyrum smithii - Stipa comata

Silty

Elymus lanceolatus - Stipa comata
Pascopyrum smithii-Stipa comata
Pascopyrum smithii-Stipa comata-
Bouteloua gracilis
Pentaphylloides floribunda/Stipa curtiseta

Pascopyrum smithii-Stipa comata-Bouteloua
gracilis

Elymus lanceolatus - (Koeleria macrantha)

Elymus lanceolatus - Stipa comata

Stipa curtiseta

Pascopyrum smithii-Stipa comata-Bouteloua

gracilis

Clayey

Pascopyrum smithii-Bouteloua gracilis

Pascopyrum smithii

Elymus lanceolatus - (Koeleria macrantha)

Appendix G. (cont.)

Range Site

Big Muddy Headwaters

Medicine Lake Area

Missouri Coteau Prairie Pothole

Thin Hilly

Schizachyrium scoparium - Muhlenbergia

cuspidata

Stipa comata - Muhlenbergia cuspidata

Shallow to
Gravel

Pascopyrum smithii-Stipa comata-Bouteloua

gracilis

Stipa comata - Bouteloua gracilis - Carex

fdifolia

Pascopyrum smithii-Stipa comata-
Bouteloua gracilis

Dense Clay

Sarcobatusvermiculatus/Pascopyrum
smithii

Pascopyrum smithii

Thin Breaks

Juniperus horizontalis/Elymus lanceolatus

Eriogonum pauciflorum - Gutierrezia

sarothrae

Pseudoroegneria spicatum

Ecological units are represented by bold-faced blocks.

** "Herbaceous vegetation" is part of the plant association name for all plant associations in this table, with the exception of those having less than 25%
cover of woody species, referred to as "shrub herbaceous vegetation" (including Artemisia carta and Sarcobatus vermiculatus types) and those having
more than 25% cover of woody species, referred to as "shrubland (including Juniperus horizontalis and Pentaphylloides floribunda types).

Appendix I.

Sheridan County plant

species of special concern

and watch species

Agastachefoeniculum (Pursh) Kuntze

Lavender hyssop

M int Family (L ami aceae)

Global Rank: G4G5; State Rank: SU - watch.

DESCRIPTION: Lavender hyssop is a rhizomatous perennial with
erect, simple, or branched stems, 60-120 cm high (Figure G-1).
The opposite leaves have broadly spade-shaped blades, 4-9 cm
long, and petioles, 5-20 mm long. They are glabrous and green
above but whitish with felt-like hairs below. The purplish flowers
are borne in whorled clusters in a spike-like inflorescence, 4-8 cm
long. The tubular corolla, 7-10 mm long, forms 2 lips at the mouth,
and the tubular calyx is purple above with 5 triangular lobes. The 4
stamens are exserted from the mouth of the flower tube.

The other two wild hyssops in the state, Agastache urticifolia and
A. cusickii, are western species with white corollas. Lavender
hyssop vegetatively resembles catnip (Nepeta cataria), from which
it differs in having a radially symmetrical calyx and lavender-
colored flowers rather than a bilaterally symmetrical calyx and
creamy white flowers with purple spots.

Reprinted with permission from the New Britton and
Brown Illustrated Flora of the Northeastern United
States and Adjacent Canada, Vol. 2, page 152, © 1952
The New York Botanical Garden.

Figure G-1

DISTRIBUTION: The center of its distribution is in the northern
plains, extending from southern Ontario, west to Saskatchewan, and
south to northern Colorado, northwestern Nebraska and northwest-
em Iowa (Great Plains Flora Association). While its distribution in
Montana is mapped as spanning the eastern V4 of the state (Great
Plains Flora 1977), the records to support that distribution do not
exist among herbaria in Montana and KANU. It has been reported
in western Montana (Dorn 1984) but these are thought to represent
places where it was cultivated in trial plantings. It was first col-
lected in eastern Montana in 1988 by Lesica (#4582; MONTU)
from Richland County. It has also been documented in both Carter
and Powder River County, on the Sioux and Ashland districts of the
Custer National Forest, respectively (Heidel and Marriott 1996). It was documented for the first time in
Sheridan County southwest of Big Muddy Creek. This reflects the fourth county and the seventh site where it
has been found, supporting the interpretation that it may be more widespread than previously known.

HABITAT: The rangewide habitat of lavender hyssop is characterized as "moist woodland, especially along
streams or lakeshores, infrequent in open, wet ditches and prairies at higher elevations" (Great Plains Flora
Association 1986). In northeastern Montana, it is restricted to wooded draws and escarpment slopes typically
dominated by green ash {Fraxinus pensylvanica), in association with chokecherry (Prunus virginiana),
Sprengel's sedge {Carex sprengelii), and northern bedstraw {Galium boreale). In southeastern Montana, it is
restricted to relatively moist areas of tall shrub cover with many of the same associated species, but found
within pine woodland.

COMMENTS: Lavender hyssop is thought to be more widespread than current records indicate in Montana,
and the breadth of its distribution supports the case for dropping it from consideration if it is not in decline.
However, its wooded draw habitat is limited and perhaps vulnerable. It also has cultural and commercial
values, but is not known to be harvested from the wild in Montana, and is easily cultivated (Kindscher 1992).
It remains on the watch list while its status is under review.

1-1

Agrimonia gryposepala Wallr.

Common agrimony

Rose Family (Rosaceae)

Global Rank: G5; State Rank: SU - watch.

Note: Assigned rank of SU and added to the watch list based in part on this study.

DESCRIPTION: Common agrimony is a perennial 30-150
cm tall with 1 -several stems in small clumps arising from
short, stout rhizomes and long fibrous roots (Figure G-2).
Leaves are alternate, divided, coarsely-toothed, and glabrous
above, with glands and hairs along the veins below. The
yellow flowers are borne in a simple, elongated inflorescence
with stalked flowers; they have 5 petals that are 3-5.5 mm
long, and usually 15 stamens. The fruit is furrowed and
shaped like a top or half-sphere, with rows of blunt, hooked
bristles in rings on top; the outer ring usually reflexed. The
achene is globose and 2.8-3.3 mm in diameter.

It is distinguished from Agrimonia striata by the absence of
hairs in the furrows of the fruit, and the presence of glands
along the axis of the inflorescence.

DISTRIBUTION: Common agrimony is widespread in
eastern North American from Maine to Ontario and North
Dakota, south to Kansas and North Carolina. It is reported for
California and New Mexico (Great Plains Flora Association
1986). It was first collected in Montana at the north end of
Bighorn Canyon National Recreation Area in 1983 and
reported in Lichvar et al. (1985) for the Canyon. It was
collected in northeastern Montana in the Big Muddy headwa-
ters for the first time as part of this study.

Reprinted with permission from the New Britton and Brown
Illustrated Flora of the Northeastern United States and Adjacent
Canada, Vol. 2, page 318, © 1952 The New York Botanical
Garden.

HABITAT: Its rangewide habitat is characterized as "moist

open woodlands, prairie ravines, and stream valleys" (Great

Plains Flora Association 1986). It is a facultative wetland

species (USDI Fish & Wildlife Service 1994). In Sheridan

County, it was found at only one wooded ravine along the

breaks of the Upper Big Muddy Valley in shade of green ash (Fraxinus pennsylvanica) at the brushy margins

of the ravine bottom with western snowberry (Symphoricarpos occidentalis) and Wood's rose (Rosa woodsii.)

Figure G-2

COMMENTS: The status of common agrimony needs further review, hinging on the status of its habitat and
vulnerability, as well as the number of records.

1-2

Asdepiasovalifolia Dene.

Oval leaf milkweed
M ilkweed Family (Asclepiadaceae)
Global Rank: G5?; State Rank: SI

DESCRIPTION:: Ovalleaf milkweed is a perennial with
usually solitary slender stems 20-60 cm high and arising from
rhizomes (Figure G-3). The erect to spreading, opposite leaves
have petioles that are up to 1 cm long, and broadly lance-shaped
to elliptic blades that are 4-8 cm long with entire margins.
Leaves are moderately long, hairy beneath, and the sap is milky.
1-3 umbrella- shaped, stalked clusters of 8-20 flowers are at the
top of the stem or in the axils of the upper leaves. Each green-
ish-white to cream flower is 8-10 mm high and borne on a hairy
stalk that is up to 20 mm long. Flowers have 5 reflexed corolla
lobes that are 5-6 mm long, and 5 erect hoods that are 4-5 mm
long and rounded at the tip; these hoods surround a greenish or
yellowish central column, and each has a conical horn inside.
The erect spindle-shaped fruits are 6-8 cm long and ca. 1 cm
wide. Each fruit has numerous seeds, each with a light brown
tuft of hairs that is 18-35 mm long. Flowering in late June-early
July.

Green milkweed (Asclepias viridiflora) and showy milkweed (A.
speciosa) also have broad leaves, but the former lacks horns
within the hoods, and the latter has pink to purple flowers.

DISTRIBUTION: The center of distribution is in the northern
Great Plains, extending east as far as Wisconsin and Illinois;
northwest to Alberta, and southwest to Wyoming. In Montana it
was recently discovered for the first time in the southeastern
comer of the state in Carter County (Heidel 1996). The Sheridan
County occurrence is in the Missouri Coteau landscape north of
Comertown. Its presence here represents the second known
occurrence in the state and the first record from northeastern
Montana.

Reprinted with permission from the New Britton and Brown
Illustrated Flora of the Northeastern United States and Adjacent
Canada, Vol. 3, page 76, © 1952 The New York Botanical
Garden.

Figure G-3

HABITAT: Ovalleaf milkweed is restricted to mesic settings, including moist meadows in pineland escarp-
ments of southeastern Montana, and rich grassland slopes on glacial till in northeastern Montana. The
Sheridan County occurrence is on rolling prairie pothole terrain, at the crest of a northwest-facing slope
dominated by northern porcupinegrass (Stipa curtiseta) below. Though this is a widespread habitat, no other
locations of the species were found, and there is question whether this represents important habitat for the
species.

COMMENTS: It persists under grazing, and is generally not preferred by stock, but the flowering stems and
pods are eaten where it is in primary range. It is associated with Stipa curtiseta in Sheridan County, a grass
with needles that deter grazing during flowering. The Carter County population was found in a wooded area
that had burned as a summer groundfire about five years earlier.

It is sporadic at best in the prairie pothole landscape of Sheridan County but is present throughout the Mis-
souri Coteau and Drift Plains counties of North Dakota (Great Plains Flora Committee 1977). Its presence in
the floras of adjoining plains states and provinces suggests that it is under-documented in Montana, but its
restriction to lush vegetation may also represent vulnerability.

1-3

C arex 9/dhnooephala Carey

M any- headed sedge

Sedge Family (Cyperaceae)

Global Rank: G4; State Rank: SI

DESCRIPTION:: Many-headed sedge is a grass-like
perennial that grows in clumps without rhizomes and has
slender stems that are 5-50 cm high (Figure G-4). The
lowest leaves are reduced to scales; the upper are flat and
1-4 mm wide. Flowers occur in 4-15 globose spikes
clustered together at the top of the stem. The lower spikes
are subtended by long, leaf-like bracts that greatly surpass
the inflorescence. Inconspicuous male flowers are at the
base of each spike. Pale green or tan perigynia are 5-7 mm
long and ca. 1 mm wide and narrowly lance-shaped with a
long beak and serrated margins. The pale, thin, lance-
shaped scales have a green midvein and are ca. 1/2 the
length of the perigynia that they subtend. Each perigynium
has 2 stigmas and an achene that is lens-shaped. Fruit
mature in July- August.

The combined characteristics of long, leaf-like lower
bracts, and long, narrow perigynia distinguish this Carex
from all other species in our area. It most closely re-
sembles slender-beaked sedge (Carex athrostachya),
which has much smaller bracts but similarities in appear-
ance and habitat as found in the county.

DISTRIBUTION: Many-headed sedge is a northern

species in North America, ranging from British Columbia

to Ontario, and south to Washington, Iowa, and New York.

In Montana, it is known from Sheridan and Glacier

counties, a historic record in the Great Falls area, and the

Flathead River and Tobacco River drainages. The Sheridan

County occurrence was near Comertown in the Missouri Coteau area.

HABITAT: The species is restricted to moist soil of meadows along streams and ponds in the valleys and on
the plains. It is a facultative wetland species (USF&WS 1994). The 1987 collection of it in the Comerton
area was described as wet meadow margin of prairie pothole, with foxtail barley (Hordeum jubatum) and
water smartweed (Polygonum amphibium) in the wetland perimeter.

COMMENTS: Many -headed sedge is one of three species that was not be relocated in the course of this
study, despite searches in the wetland margins where it had first been collected. It was originally collected
from the County in 1987, a drought year, when it was noted as rare. It is not known whether this species
remains vegetative when there is taller dense vegetation. As part of the rest-rotation grazing regime, it would
be most insightful to survey for it in midsummer during the year it was subject to early-season grazing. It is
among a group of species benefiting by restoration of wetland margins.

Figure G-4

1-4

Centunculusminimus{L.) Krause

C haffweed

Primrose Family (Primulaceae)

Global Rank: G5; State Rank: S2

Note: Reranked from S 1 to S2 based in part on results of this study.

DESCRIPTION:: Chaffweed is an annual with prostrate or
erect stems, 2-10 cm long, that are branched near the base
and root at the nodes (Figure G-5; SID 849). The alternate
leaves, 5-10 mm long, are egg to spoon-shaped with entire
margins. Foliage is glabrous. Solitary, inconspicuous
flowers on short stalks occur in the leaf axils. Each flower
has a deeply 4-lobed calyx, 2-3 mm long, and a small, pink,
4-lobed, tubular corolla, ca. 1 mm long, that withers on the
maturing ovary. There are 4-5 stamens, and the fruit is a
globose capsule that is ca. 2 mm long. Flowering and
fruiting June-September.

Sea milk-wort (Glaux maritima) is similar but has lower
leaves that are opposite each other and it is perennial. A
hand lens or microscope may be needed for positive identifi-
cation.

DISTRIBUTION: Chaffweed is native to Europe and North
America, widely but sparsely distributed from. Nova Scotia
to Saskatchewan, south to Florida and Mexico.

Jeanne R. Janish, from Vascular Plants
of the Pacific Northwest

Figure G-5

In Montana, it is known from the Bitterroot Valley; from a

historical record in the Flathead Valley, a historical record in

Missouri River wetlands near Great Falls area, and from

Sheridan and Valley counties for a total of 7 extant records and 3 historical ones. The Sheridan County

occurrences are in the Missouri Coteau area north of Comertown.

HABITAT: Chaffweed grows in vemally wet, sparsely vegetated soil around ponds and along rivers and
streams in the valleys and on the plains. It is an obligate wetland species (USF&WS 1994).

It occupies the margins of seasonal wetlands in Sheridan County, on silty soils that dry out early in the season.
The vegetation is relatively low-growing, including the following associated species: needle spike-rush
(Eleocharis acicularis), western wheatgrass (Pascopyrum smithii), mat muhly (Muhlenbergia richardsonis),
ticklegrass {Agrostis scabra), and annual forbs like purslane speedwell (Veronica peregrina) and field chick-
weed (Cerastium arvense).

COMMENTS: Its habitat is not affected by trampling except when soils are saturated in spring. It is among a
group of species potentially benefiting by restoration of wetland margins. Kentucky bluegrass (Poa pratensis)
is sometimes present and assumes dominance, competing with chaffweed.

1-5

Chenopodium subglabrum (S. Wats.) A. Nels.

Smooth goosefoot

Goosefoot Family (Chenopodiaceae)

Global Rank: G4; State Rank: SI

Note: Global rank was changed from G3 to 04 based on consultation
with botanists in Nebraska and Wyoming.

DESCRIPTION: Smooth goosefoot is an annual with erect,
simple or more often branched stems usually 10-40 cm high
(Figure G-6; SID 1104). The alternate leaves are linear with entire
margins, single veined, glabrous, up to 3 cm long. Flowers are
small, green, and grouped in remote clusters on the branched stem.
Each flower lacks petals but has 5 glabrous sepals and 5 stamens.
The 1 -seeded fruit is compressed, hemispherical and relatively
large; 1.2-1.6 mm across, exposing a jet-black fruit at maturity that
readily separates from the pericarp. Fruiting in late June- July.

Chenopodium subglabrum is related to slimleaf goosefoot (C.
leptophyllum) and desert goosefoot (C. dessicatum) but it does not
have a farinose perianth surface. It tends to have larger fruits 1.2-
1.6 mm in diameter and more widely spaced glomerules. It is
further distinguished from the latter in that it has leaves single-
veined rather than 3 -veined from the base.

DISTRIBUTION: Smooth goosefoot is centered in Nebraska and
South Dakota, also documented from Manitoba to Alberta south to
Kansas, Utah and Nevada (Crawford 1973, and Biosource 1999).
Plants of the Pacific Northwest are said to differ from Great Plains
material (Crawford 1973) and their proper disposition has not been
resolved. It is also reported to occur sparsely in the Midwest,
treated in early floras as a synonym of C. leptophyllum; further
specimen review may be needed.

In Montana, it is known from 5 occurrences in Carter, Cascade and
Sheridan counties, and one record in Custer County that may be
extirpated. The Sheridan County occurrence is in the Medicine
Lake sandhills.

Reprinted with permission from the New Britton and
Brown Illustrated Flora of the Northeastern United
States and Adjacent Canada, Vol. 2, page 502, ©
1952 The New York Botanical Garden.

Figure G-6

HABITAT: It occupies sparsely vegetated sand dunes and sandy terraces of major rivers on

the plains; at early stages of succession in both settings. In the study area it is restricted to active blowouts or

lee slope deposits; on the loose sand at the side of the "bowl" or on the rim. Associated species include Indian

ricegrass (Oryzopsis hymenoides), lemon scurfpea (Psoralidium lanceolatum), andFendler cat's-eye

(Cryptanthafendleri).

COMMENTS: Maintenance of early serai habitat in the upland settings may require some level of distur-
bance, i.e., periodic reduction in grass cover. Maintenance of early serai habitat in the riparian setting may
require intact flow regimes and landscape processes over a larger scale. Tamarisk control is needed in riparian
habitat of southeastern Montana.

1-6

Cryptantha fendleri (Gray) Greene

Fendlercat's-eye

Borage Family (Boraginaceae)

Global Rank: G4; State Rank: S2

Note: Reranked from SI to S2 based on results of this study.

DESCRIPTION: Fendler cat's-eye is an annual with
simple or branched stems that are 5-20 cm high (Figure
G-7). The alternate, narrow, strap-shaped leaves may be
up to cm long; those at the base are usually brown by the
time the plant is fruiting. Foliage is sparsely covered with
spreading hairs. Tiny white flowers are borne on coiled
stalks that unwind and elongate as flowering progresses
from the base upward. The corolla is ca. 1 mm high and
has a small, united portion below and 5 spreading petals
above. The calyx is covered with stiff, straight hairs and
becomes 4-6mm long in fruit. Within each fruiting calyx
are 4 smooth, shiny, narrowly lance- shaped nutlets that
are ca. 1.5 mm long and 1/3 as wide; 1 or more of these
may be missing. Flowering in May-early July.

Annual species of Cryptantha are distinguished by
characters of the seeds. Fendler cat's-eye (Cryptantha
fendleri) is distinguished by having 4 smooth, shiny
nutlets that are lance- shaped and 1/3 as wide as they are
long. A hand lens or microscope is needed for positive
identification.

Jeanne R. Janish, from
Vascular Plants of the
Pacific Northwest

Figure G-7

DISTRIBUTION: Fendler cat's-eye is a western North

American species distributed from southern British

Columbia to Saskacthewan, and south to Oregon, New

Mexico, and Nebraska. In Montana, the species is know

from two large sandhill areas at opposite comers of the state; the Centennial sandhills in Beaverhead County,

and the Medicine Lake sandhills in Sheridan County. In addition, there was a 1943 record from north of the

Medicine Lake sandhills in a roadside setting (Hotchkiss #6900 MONT). It may indicate that the species was

once more widespread across gentle sandplains, that it was more widespread around the time of drought

years, and/or that it may be adventive in roadside settings under some conditions.

HABITAT: Open areas of sand dunes in the valleys and on the plains provide habitat for Fendler cat's-eye. It
occupies a range of sparsely-vegetated settings and successional stages, as has been documented in the
Centennial Valley (Lesica and Cooper 1999). It is the most widespread of the species sought in the Medicine
Lake Sandhills. It is not only found in blowout, but throughout much of the gentler sandplains where grass
cover is discontinuous.

COMMENT: Fendler' s cat's-eye does not grow among tall, dense grasses. The widespread practice of
seeding sandhills to crested wheatgrass (Agrpopyron cristatum) has reduced available habitat. It was found to
persist under ongoing heavy grazing, and persists where brittle pricklypear {Opuntia fragilis) is common. The
abundance of cactus may indicate past heavy grazing. A conceptual management framework involving this
and other sandhills species is presented in Lesica and Cooper (1999) for southwestern Montana. Invasion of
leafy spurge {Euphorbia esula) is also a potential threat.

The series of scattered plants in the Medicine Lake sandhills are taken to represent one giant population
complex; the largest of two in the state. Its state rank was changed because it is unaffected by most manage-
ment actions, but it was retained as a species of special concern because it is still considered vulnerable.

1-7

Cyperusschweinitzii Torr.

Schweinitz' flatsedge

Sedge Family (Cyperaceae)

Global Rank: G 5; State Rank: S2

DESCRIPTION: Schweinitz' flatsedge is a grass-like peren-
nial with stems that are 10-40 cm high, arising from short,
irregularly swollen rhizomes (Figure G-8). The leaves are 1-4
mm wide and located mostly near the base of the stem. The
inflorescence is subtended by 3-6 long, leaf-like bracts, some
of which are wider than the leaves. The infloresence is made
up of ascending clusters of flattened spikelets that are 5-25
mm long and borne on stalks that are very short to long. The
flowers are crowded opposite each other and consist only of a
small, pointed scale, that is ca. 3-4 mm long and subtends 3
stamens and an ovary. The seed is triangular in cross-section.
Fruit mature in late June- July.

This is our only perennial Cyperus and is the only one occur-
ring in upland habitat.

DISTRIBUTION: Schweinitz' flatsedge extends from Alberta
to New Mexico and east from Quebec to West Virginia. It is
concentrated in the Great Lakes and the Great Plains. In
Montana, it is known from eight records in five eastern
counties. The Sheridan County occurrence is in the Medicine
Lake sandhills area.

HABITAT: Schweinitz' flatsedge occupies sparsely vegetated
sand dunes, in blowouts and open ridges. It is often on loose
sand slopes in the "bowl" of a blowout. It is associated with
Indian ricegrass (Oryzopsis hymenoides), needle-and-thread
(Stipa comata), lemon scurpea (Psoralidium lanceolatum), and
Fendler cat's-eye (Cryptanthafendleri.)

Reprinted with permission from the New Britton and
Brown Illustrated Flora of the Northeastern United States
and Adjacent Canada, Vol. 1, page 253, © 1952 The New
York Botanical Garden.

Figure G-8

COMMENTS: Maintenance of early serai sandhill habitat

may require some level of disturbance, i.e., periodic reduction in grass cover. It is present in low numbers on

the rolling sandplains where brittle pricklypear (Opuntia fragilis) is abundant and may reflect past heavy

grazing.

The series of scattered plants in the Medicine Lake sandhills are estimated at 1,000+ plants and are taken to
represent one giant population complex; the largest in the state.

1-8

Dalea villosa (N utt.) Spreng. var. villosa

Silky prairie clover

Bean Family (Fabaceae or Leguminasae)

Global Rank:G5T?; State Rank: SI

DESCRIPTION: Silky prairie clover is a perennial with 1-many
ascending or lax, branched stems that are 20-40 cm high, and
arising from red-orange roots and a rootcrown (Figure G-9). The
alternate, pinnately compound leaves are 2-4 cm long and have 11-
21 linear leaflets. The foliage has numerous sunken glands with
dense long hairs. The pink to rose-purple flowers are densely
crowded in cylindrical spikes that are 3-12 cm long, at the ends of
stems and branches. Each flower is 4-6 mm long and has 4 sepa-
rate petals, a densely spreading, hairy, 5-lobed, cup-shaped calyx,
and 5 stamens that are usually longer than the petals. The narrowly
egg-shaped pods are 2-3 mm long and densely long and hairy.

Other Dalea in Montana usually have 1 1 or more leaflets, and are
not as conspicuously hairy. The combination of the long, hairy
calyx and the 5 stamens further separate this species from other
Dalea and from species of Psoralidium and Amorpha.

DISTRIBUTION: This species has its center of distribution in the
Great Plains, ranging from Saskatchewan and Manitoba to Wis-
consin, and south to Colorado and Texas. In Montana, it is known
from four records in Carter, Richland and Sheridan counties. The
Sheridan County occurrence is in the Medicine Lake area on
gentle sandplains outside of the sandhills. It is likely to occur in
the sandhills but was not found in survey to date.

HABITAT: Silky prairie clover grows on loose sand of sand dunes

or wind-eroded deposits around sandstone outcrops. Its habitat in

Sheridan County is incompletely documented or different in that it

was not found growing on any of the loose sand in sand dunes, but

only at erosion points along a section-line road and a nearby

pasture 2-track. In this setting, it grows literally at the edge of

loose sand, in greatest numbers where prairie sandreed

(Calamovilfa longifolia) and sandhill bluestem (Andropogon

hallii) are abundant, but also present with needle-and- thread (Stipa comata). The "natural" habitat for silky

prairieclover elsewhere in the state is in or at the edge of small blowouts, representing early successional

habitat and the Oryzopsis hymenoides - Psoralidium lanceolatum plant association.

COMMENTS: This species is favored by some level of disturbance and may decline in the absence of
disturbance. It is also palatable, and a decreaser under grazing (Smith 1976), with limited capacity to resprout.

Reprinted with permission from the New Britton and
Brown Illustrated Flora of the Northeastern United
States and Adjacent Canada, Vol. 2, page 411, © 1952
The New York Botanical Garden.

Figure G-9

1-9

Lobelia kalmii L.

Kalm's lobelia

Bellflower Family (Campanulaceae)

Global Rank: G5; State Rank: SU

Note: Assigned rank of SU and added to watch list in part based on results of this study.

DESCRIPTION: Kalm's lobeha is a slender perennial 10-50 cm
tall, with a single branched stem arising from a small basal rosette
of leaves and a slender rhizome (Figure G-10). Basal leaves are
narrower at the base than the tip, with rounded tips. Stem leaves are
sessile, 0.5-3 mm wide with pointed tips, and decrease in size
toward the top of the stem. The elongated infloresence is made up
of a loose series of 2-12 flowers on short stalks. The corolla is pale
to dark blue, 7-10 mm long, with lower lobes curving downward.

Distinguished from Lobelia spicata by the stem leaves 3 m or less
wide, and usually a much narrower stem 1.5 or less in diameter.

DISTRIBUTION: Kalm' s lobelia is a boreal species known from
Nova Scotia to Alberta, south to Pennsylvania, Iowa, North Dakota,
Colorado and northeastern Washington. In Montana, it is known 5
historic collections in Flathead County, 1 historic collection in
Missoula Co., and a historic collection that described the location
simply as "Missouri Valley".

In Sheridan County, it was first documented by a 1943 collection
record near Dagmar that corresponds with the population in this
study, where it occurs in one widely- scattered population complex
across four sections along Lake Creek and associated potholes.

HABITAT: In Montana, it is restricted to rich fens, and is an
obligate wetland species (USF&WS 1994). In Sheridan County, it is
in small areas of patterned peatland, with distinctive parallel
mound-pool (string-flark) bands (Chadde et al. 1998). The domi-
nant species in its untrampled habitat is mainly few-flowered spike-
rush (Eleocharis quinqueflora), and associated species include
green sedge (Carex viridula), rush aster (Aster junciformis), mat

muhly (Muhlenbergia richardsonis), jointed rush (Juncus articulatus), marsh arrowgrass (Triglochin
palustre), wedgegrass (Sphenopholis obtusata), northern bog violet {Viola nephrophylla), and small-flowered
grass-of-parnassus (Parnassia palustris).

Reprinted with pennission from the New
Britton and Brown Illustrated Flora of the
Northeastern United States and Adjacent
Canada, Vol. 2, page 321, © 1952 The New
York Botanical Garden.

Figure G-10

COMMENTS: This species persists with grazing, but is impacted by heavy prolonged trampling that changes
the mound-pool microtopography and increases competing vegetation cover. The associated species that
increase under trampling include common arrowgrass (Triglochin maritimum), common threesquare (Scirpus
pungens), and water sedge (Carex aquatilis). Species records have not been compiled from all Montana
herbaria to date and it may be considered for addition to the species of special concern list pending further
status review.

1-10

L obeli a spicata L am .

Pale-spiked lobelia

Bellflower Family (Campanulaceae)

Global Rank: G5; State Rank: SI

Note: Reranked from SH to SI based on results of this study.

DESCRIPTION: Pale-spiked lobelia is a perennial with unbranched stems
that are 20-80 cm high (Figure G-11). The oblong, lance-shaped stem leaves
are 5-10 cm long and 0.4-2 cm wide, have toothed margins and short
petioles, and become smaller up the stem. Foliage is glabrous to sparsely
short-hairy. Flowers are 7-12 mm long and are bom on short, 2-5 mm long
stalks in a sparingly branched, narrow, crowded inflorescence. Each flower
has 5 narrow sepals that are 5-9 mm long and a light blue, tubular, 4-10 mm
long corolla that flares into a spreading 2-lobed upper lip and a 3-lobed
lower lip. The ovary is below the base of the corolla and matures into a
nearly globose capsule that is 3-5 mm high.

Kalm's lobelia (Lobelia kalmii) has linear stem leaves 0.3 cm or less wide,
and is confined to saturated soils. Most other species of Campanulaceae
with similar flowers are annuals.

DISTRIBUTION: Pale-spiked lobelia occurs in grassland landscapes from
Ontario west to Saskatchewan, and south from Georgia to Texas. In Mon-
tana, it is known from two historic records including a 1924 collection in
Richland County and a 1943 collection in Sheridan County near Medicine
Lake. The historic record near Medicine Lake ("4 miles northeast of
Medicine Lake") is thought to give directions from the Lake rather than the
Town. This would put it in the Lake Creek Valley, but it was not relocated
here. In this study, two more occurrences were documented in sandplains
below Brush Mountain and in the Missouri Coteau prairie potholes.

HABITAT: Pale-spike lobelia grows in a variety of moist meadow settings
on the plains. It is a facultative wetland species (USF&WS 1994).

Reprinted with pennission from the New
Britton and Brown Illustrated Flora of the
Northeastern United States and Adjacent
Canada, Vol. 3, page 322, © 1952 The
New York Botanical Garden.

Figure G-11

In Sheridan County, it was found mainly in narrow bands along wetland mar-
gins, including prairie potholes and shallow meandered wetlands in outwash
channel. The historic Medicine Lake collection was made from a setting de-
scribed as "tallgrass." The associated vegetation of the two more recent records
is dominated by clustered field sedge (Carex praegracilis), mat muhly
(Muhlenbergia richardsonis), western wheatgrass (Pascopyrum smithii) or

switchgrass (Panicum virgatum); and other species present include meadow anemone (Anemone canadensis),
mountain blue-eyed-grass (Sisyrinchium montanum), northern reedgrass (Calamagrostis stricta), wedgegrass
(Sphenopholis obtusata), and wild licorice (Glycyrrhiza lepidota).

COMMENTS: Exotic species like Kentucky bluegrass (Poa pratensis) and ticklegrass (Agrostis scabra) are
invasive and competitive in this species' habitat. Its response to grazing is not known but the pastures where
it occurs are not grazed during flowering time. It is among a group of species potentially benefiting by
restoration of wetland margins. The two populations in this study represent the only two records of recent
decades in the state.

1-11

Phl<»( andicola E . N els.

Plains phlox

Phlox Family (Polemoniaceae)

Global Rank: G4; State Rank: S2

DESCRIPTION: Plains phlox is a perennial
with loosely tufted stems that are 4-10 cm
high arising from creeping rhizomes (Figure
G-12). The 5-8 pairs of opposite, linear leaves
have prominent midveins and whitish bases
and are 10-25 mm long, ca. 1 mm wide and
come to a sharp point. Foliage is glabrous to
sparsely hairy. Stems are white. 1-5 white
flowers are borne at the stem tips. Each flower
has 5 petals and a tubular corolla. The calyx is
also tubular, with 5 lobes, tangled long hairs,
and 6-11 mm length. Flowering in May-early
June.

Distinguished from Hood's phlox (Phlox
hoodii) by leaf length over 10 mm long, and
from alyssum-leaved phlox (P. alyssifolia) by
leaf width less than 2 mm wide. Flowers are
needed for positive identification, and hybrid-
ization between these species is reported
elsewhere in the range.

Figure G-12
DISTRIBUTION: Plains phlox is a Great

Plains species ranging from Montana and

North Dakota, south to Colorado and Kansas. In Montana, it is known from ten occurrences in five eastern

counties. All of the known Sheridan County occurrences are on sandplains north and east of the Medicine

Lake sandhills.

HABITAT: It occupies sandy soil of grasslands and open pine woodlands on the plains as a mid-successional
species. Unlike most of the other sand-loving species surveyed in this study, it does not occupy dunes, and
often grows in relatively dense vegetation cover. It is found on a variety of sandplains and in loose sand
below sandstone outcrops. In Sheridan County,

COMMENTS: Plains phlox is an early-blooming plant that was not surveyed before late June in this study.
Further survey is warranted. It occupies well-established grassland, but may benefit by periodic reduction in
canopy cover. One of the places where it was found in highest numbers was a calving pasture.

The Sheridan County records represent the largest known numbers of records and total plants in the state.

1-12

Primula incana M.E.J ones

M ealy primrose

Primrose Family (Primulaceae)

Global Ranl<: G4G 5; State Ranl<: S2

DESCRIPTION: Mealy primrose is a perennial with leafless stems
10-45 cm tall, arising from a basal rosette of leaves and fibrous roots
(Figure G-13). Leaves usually have a mealy, whitish covering, are
elliptic or oblanceolate with slightly toothed margins, 0.3-1.6 cm
wide, and up to 6 cm long Including the winged petioles.
Infloresences are capitate, 7-19 flowered, surmounting involucral
bracts that are 0.5-1 cm long, oblong, with a whitish, mealy cover-
ing, and pouched at the base. The calyx also has a whitish, mealy
covering, is cylindrical, 0.4-0.7 cm long, and divided up to 1/3 its
length by lanceolate teeth that have a glandular surface. The corolla
is lavender with a yellow throat, forming a tube that is equal or
slightly longer than the calyx, app. 0.4-0.8 cm long and wide.
Stamens are ca. 1 mm long and of equal length. The capsule is
cylindrical to slightly elliptical, and equaling or slightly exceeding
the length of the calyx. Flowering in June.

Primula incana differs from Parry's primrose (P. parrryi) in that the
corolla is less than 1 cm wide, the leaves lie low to the ground, and it
is not found at alpine or subalpine habitats. It most closely resembles
Idaho primrose (P. alcalina), not known from eastern Montana,
which it also differs in having a lilac rather than white corolla, and
generally longer calyx and corolla.

DISTRIBUTION: Mealy primrose is a boreal species ranging from
Alaska to Ontario, extending south to Utah, Colorado, and North
Dakota. It was only known from western Montana prior to this
study, documented from the Upper Clarks Fork River, Jefferson
River, and Madison River drainages. Front Range, and historically
known from the Beartooth Mountains. In Sheridan County, it is
known only from one occurrence in the Missouri Coteau area. Of the
20 records in the state, several are historic.

Jeanne R. Janish, from Vascular Plants of the
Pacific Northwest

Figure G-13

HABITAT: This species occupies alkaline meadows or peatlands on the plains, and in valley and foothill
zones. It is a facultative wetland species (USF&WS 1994). In Sheridan County it was restricted to seep
habitat with marl deposits beside an alkali lake. The most common associated species are Baltic rush (Juncus
balticus), common threesquare (Scirpus pungens), common arrowgrass (Triglochin maritimum), and common
silverweed (Potentilla anserina). Other species present include mat muhly (Muhlenbergia richardsonis),
golden sedge (Carex aurea), Parry's sedge (C. parryana), wooly sedge (C. lanuginosa), small-flowered grass-
of-parnassus (Parnassia palustris), mountain blue-eyed-grass (Sisyrinchium montanum) and sea-milkwort
(Glaux maritima). This species occupies the same habitat as Kalm's Lobelia (Lobelia kalmii) on Great Plains
peatlands outside of Montana, but they were not found together in Sheridan County.

COMMENTS: Like Lobelia kalmii, it may be eliminated by heavy prolonged trampling that changes the
mound-pool microtopography and increases competing vegetation cover. The Sheridan County occurrence is
the only known occurrence in eastern Montana.

1-13

ScirpusheterodiaetusChdse

Slender bulrush

Sedge Family (Cyperaceae)

Global Rank: G5; State Rank: SI

DESCRIPTION: Slender bulrush is a tall, glabrous,
grass-like perennial with firm, round stems that are
1-2 m tall and arising from stout brown rhizomes
(Figure G-14). The few leaves are borne near the
base and have a sheath surrounding the stem, but the
blade is small and tapers to a point. Numerous
slender- stalked, solitary spikelets are borne on the
spreading branch tips of an open, terminal inflores-
cence. Each egg-shaped spikelet is up to 17 mm long
and has several flowers arranged in a tight spiral.
Flowers consist of a single scale that is up to 5 mm
long; it subtends 3 stamens and an ovary with 4
white bristles that are as long as the scales and
arising from the base. The 3-sided achene is ca. 3
mm long with a short beak and 3 stigmas. Fruiting in
August.

The common hardstem bulrush (Scirpus acutus) and
softstem bulrush {S. validus) are very similar but
have 2 stigmas and sessile spikelets arranged in
small clusters.

Jeanne R. Janish, from Vascular Plants
Pacific Northwest

Figure G-14
DISTRIBUTION: Slender bulrush is distributed

from Washington and Oregon east to Quebec and

Massachusetts, centered in the Great Plains and extending south to Oklahoma and Kentucky.

In Montana, it is known from only three occurrences to date, including wetlands near the Flathead Valley and
in northeastern Montana in the Medicine Lake area.

HABITAT: Slender bulrush occupies semi-permanent marshes and edges of lakes and ponds on the plains. It
is an obligate wetland species (USF&WS 1994). It is common or abundant under "fresh" water conditions
elsewhere in the Missouri Coteau ( >225 |Jmhos/cm; Stewart and Kantrud 1972). It was reported as "locally
common" in association with Eleocharis palustris at its only other collection site in Montana from Phillips
County. Its habitat at the site of the 1943 collection in Sheridan County was described only as "marsh."

COMMENTS: Slender bulrush is one of three species that was not relocated in the course of this study. It
was described as "abundant" where it was originally collected on the Refuge in 1943. Wetland habitat in parts
of the Lake Creek Valley was subsequently altered by a system of levees to increase open water habitat;
implications for the species are unknown. The limited surveys on the Refuge to date should be expanded and
any available water chemistry data used to identify and search wetlands with "fresh" water condition.

1-14

Sis^inchium septentrionale B'lckn.

Northern blue-eyed grass

IrisFamily (Iridaceae)

Global Rank: G3G4; State Rank: SI

DESCRIPTION: Northern blue-eyed grass is a tuft-forming perennial,
app. 20-30 cm tall, arising from fibrous roots (Figure G-15). Light green
leaves are up to 2/3 the height of the stem and 1-2.3 mm wide. Stems are
1-1.9 mm wide, surmounted by terminal infloresences. The outer bract is
24-55 mm long, nearly twice the length of the inner bract or longer,
united basally 1.2-2.8 mm. The inner bract has broad, clear margins and
is not swollen at the base. 1-5 flowers are borne on slender stalks app.
same length as the inner bract. Tepals are blue- violet with yellow bases;
the outer are 9-12 mm long. The capsule is 2.7-5 mm long. Flowering in
June.

It is distinguished from the mountain blue-eyed grass (Sisyrinchium
montanum) in not having an inner bract with a swollen base, or an outer
bract that widens above the tip of the inner bract. Stems are usually
narrower; 1.9 mm or less wide.

Note: This species is not treated consistently between floras, and the
information above represents the revisionary taxonomic work presented
in Cholewa and Henderson (1984) for the genus in western states. It is
otherwise treated as part oi Sisyrinchium angustifolium in the flora of the
Great Plains (Great Plains Flora Association 1986) and of the Canadian
provinces (Scoggan 1978). Many authors treat S. angustifolium as
synonymous with S. montanum (e.g. Dorn 1984). Of these three closely-
related species, only two are in Montana, and further taxonomic review
is underway as part of the Flora of North America project to clarify the
distribution and status of each.

Figure G-15

DISTRIBUTION: Northern blue-eyed grass is distributed in the Great
Plains from Alberta and Saskatchewan to Texas, and west of the conti-
nental divide in Idaho. In Montana, it is only known from the rolling Missouri Coteau area of Sheridan
County, where it was collected east of Comertown. The more common Sisyrinchium montanum was docu-
mented in the eastern end of the County in Medicine Lake sandhills, alkali lake springs and peatlands, and
around Brush Mountain.

HABITAT: This species is restricted to a low prairie or wet meadow settings. It was collected in Sheridan
County from a prairie pothole margin in association with meadow anemone {Anemone canadensis) and
meadow hawksbeard (Crepis runcinata).

COMMENTS: Northern blue-eyed grass is one of three species that was not relocated in the course of this
study. It is among a group of species potentially benefiting from further survey in and restoration of wetland
margins. It is the only plant species of concern in Sheridan County that is known from no other counties in
Montana.

1-15

Appendix J.
Flora of Sheridan County

Scientific Name

Flora of Sheridan County

Common Name

Origin Family Code

Abronia fragrans

Fragrant White Abronia

NYCTAG

Abronia micrantha

Small-flowered Abronia

NYCTAG

Acer negundo var interius

Box-elder

ACERAC

Achillea millefolium var lanulosa

Common Yarrow

ASTERA

Actaea rubra

Baneberry

RANUNC

Agoseris cuspidata

Toothed Micro seris

ASTERA

Agoseris glauca var glauca

Pale Agoseris

ASTERA

Agrimonia gryposepala

Common Agrimony

ROSACE

Agropyron cristatum

Crested Wheatgrass

POACEA

Agropyron dasystachyum - see Elymus

lanceolatus

Agropyron repens

Quackgrass

POACEA

Agropyron smithii - see Pascopyron smithii

Agropyron spicatum - see Pseudoroegneria

spicata

Agrostis scabra

Agrostis stolonifera

Alisma gramineum

Alisma triviale

Allium textile

Alopecurus aequalis

Alyssum desortum

Amaranthus albus

Amaranthus blitoides

Amaranthus graecizans

Amaranthus powellii

Amaranthus retroflexus

Ambrosia artemisiifolia

Ambrosia psilostachya

Ambrosia trifida var trifida

Amelanchier alnifolia

Amelanchier sanguinea

Ammannia coccinea

Andropogon gerardii

Andropogon hallii

Andropogon scoparius - see Schizachyrium

scoparium

Androsace occidentalis

Androsace septentrionalis

Anemone canadensis

Anemone cylindrica

Anemone multifida

Tickle-grass

POACEA

Creeping Bentgrass

POACEA

Narrowleaf Waterplantain

ALISMA

American Waterplantain

ALISMA

Textile Onion

LILIAC

Short-awn Foxtail

POACEA

Desert Alyssum

BRASSI

Tumbleweed

AMARAN

Prostrate Pigweed

AMARAN

Prostrate Pigweed

AMARAN

Powell's Amaranthus

AMARAN

Rough Pigweed

AMARAN

Annual Ragweed

ASTERA

Western Ragweed

ASTERA

Giant Ragweed

ASTERA

Western Serviceberry

ROSACE

Low Serviceberry

ROSACE

Scarlet Ammannia

LYTHRA

Big Bluestem

POACEA

Sandhill Bluestem

POACEA

Western Fairy-candelabra

PRIMUL

Pygmy flower Rockjasmine

PRIMUL

Meadow Anemone

RANUNC

Candle Anemone

RANUNC

Cliff Anemone

RANUNC

J-l

Flora of Sheridan County

Scientific Name

Common Name

Origin Family Code

Anemone patens

Antennaria microphylla

Antennaria neglecta

Antennaria neodioica

Antennaria parvifolia

Apocynum androsaemifolium

Apocynum cannabinum

Apocynum sibiricum

Arab is hirsuta

Arabis holboellii var collinsii

Arabis holboellii var pinetorum

Arctium lappa

Arctium minus

Arctostaphylos uva-ursi

Arenaria lateriflora

Argemone polyanthemos

Aristida purpurea

Arnica fulgens

Arnica sororia

Artemisia biennis

Artemisia campestris

Artemisia cana

Artemisia caudata

Artemisia dracunculus

Art em is ia frig ida

Artemisia glauca

Artemisia longifolia

Artemisia ludoviciana ssp ludoviciana

Artemisia tridentata ssp wyomingensis

Asclepias ovalifolia

Asclepias pumila

Asclepias speciosa

Asclepias verticillata

Asclepias viridiflora

Aster ascendens

Aster borealis

Aster canescens

Aster chilensis

Aster commutatus

Aster falcatus

Aster frondosa

Aster hesperius

Aster junciformis

Pasqueflower

RANUNC

Rosy Pussy-toes

ASTERA

Field Pussy-toes

ASTERA

Northern Pussy-toes

ASTERA

Nuttall's Pussy-toes

ASTERA

Spreading Dogbane

APOCYN

Hemp Dogbane

APOCYN

Clasping-leaved Dogbane

APOCYN

Hairy Rockcress

BRASSI

Holboell's Rockcress

BRASSI

Holboell's Rockcress

BRASSI

Great Burdock

ASTERA

Common Burdock

ASTERA

Kinnikinnick

ERICAC

Bluntleaf Sandwort

CARYOP

Prickly Poppy

PAPAVE

Red Threeawn

POACEA

Orange Arnica

ASTERA

Twin Arnica

ASTERA

Biennial Wormwood

ASTERA

Pacific Sagewort

ASTERA

Silver Sagebrush

ASTERA

Pacific Sagewort

ASTERA

Wormwood

ASTERA

Fringed Sagewort

ASTERA

Tarragon

ASTERA

Long-leaved Sagewort

ASTERA

Sagewort

ASTERA

Wyoming Big Sagebrush

ASTERA

Ovalleaf Milkweed

ASCLEP

Plains Milkweed

ASCLEP

Showy Milkweed

ASCLEP

Whorled Milkweed

ASCLEP

Green Milkweed

ASCLEP

Long-leaved Aster

ASTERA

Rush Aster

ASTERA

Hoary Aster

ASTERA

Long-leaved Aster

ASTERA

White-prairie Aster

ASTERA

White-prairie Aster

ASTERA

Alkali Aster

ASTERA

Marsh Aster

ASTERA

Rush Aster

ASTERA

J -2

Flora of Sheridan County

Scientific Name

Common Name

Origin Family Code

Aster laevis

Aster longifolius

Aster oblongifolius

Aster ptarmicoides - see Solidago

ptarmicoides

Astragalus aboriginum

Astragalus adsurgens

Astragalus agrestis

Astragalus americanus

Astragalus bisulcatus

Astragalus caespitosus

Astragalus canadensis

Astragalus ceramicus var filifolius

Astragalus crassicarpus var crassicarpus

Astragalus drummondii

Astragalus flexuosus

Astragalus geyeri

Astragalus gilviflorus

Astragalus gracilis

Astragalus longifolius

Astragalus lotiflorus

Astragalus missouriensis

Astragalus pectinatus

Astragalus purshii

Astragalus spatulatus

Astragalus striatus

Astragalus tenellus

Astragalus vexilliflexus

Atriplex argentea

Atriplex canescens

Atriplex confertifolia

Atriplex dioica - see A. suckleyi

Atriplex gardneri

Atriplex hastata

Atriplex hortensis

Atriplex patula

Atriplex powellii

Atriplex prostrata

Atriplex rosea

Atriplex suckleyi

Axyris amaranthoides

Bahia oppositifolia - see Picradeniopsis

oppositifolia

Smooth Aster
Rush Aster
Aromatic Aster

Indian Milk- vetch
Standing Milk-vetch
Field Milk- vetch
American Milk- vetch
Two-Groove Milk-vetch
Draba Milk- vetch
Canada Milk- vetch
Painted Milk-vetch
Ground Plum
Drummond's Milk- vetch
Wiry Milk- vetch
Geyer's Milkvetch
Plains Orophaca
Slender Milk-vetch
Painted Milk-vetch
Lotus Milk-vetch
Missouri Milk-vetch
Tine-leaved Milk- vetch
Pursh's Milk- vetch
Draba Milk- vetch
Standing Milk-vetch
Pulse Milk-vetch
Bent-flowered Milk- vetch
Silverscale
Four- wing Saltbush
Shadscale

Gardner's Saltsage
Common Orache
Garden Orache
Fat-hen

Powell's Saltbush
Triangle Orache
Red Orache
Rillscale
Russian Pigweed

ASTERA

FABACE

CHENOP

J -3

Flora of Sheridan County

Scientific Name

Common Name

Origin

Family Code

Balsamorhiza incana

Hoary Balsamroot

ASTERA

Beckmannia syzigachne

American Sloughgrass

POACEA

Berteroa incana

Berteroa

BRASSI

Besseya wyomingensis

Wyoming Kittentail

SCROPH

Betula occidentalis

Water Birch

BETULA

Bidens cernua

Nodding Beggar- ticks

ASTERA

Bidens comosa

Threelobed Beggar-ticks

ASTERA

Bidens f rondo sa

Leafy Beggar-ticks

ASTERA

Bidens vulgata

Tall Burr-marigold

ASTERA

Boisduvalia glabella

Smooth Spike-primrose

ONAGRA

Botrychium campestre

Prairie Dunewort

OPHIOG

Botrychium virginianum

Virginia Grape-fern

OPHIOG

Bouteloua curtipendula

Sideoat Grama

POACEA

Bouteloua gracilis

Blue Grama

POACEA

Brassica juncea

Indian Mustard

BRASSI

Brassica kaber

Wild Mustard

BRASSI

Brickellia eupatorioides

False-boneset

ASTERA

Bromus carinatus

Mountain Brome

POACEA

Bromus commutatus

Hairy Chess

POACEA

Bromus inermis

Smooth Brome

POACEA

Bromus japonicus

Japanese Brome

POACEA

Bromus marginatus

Mountain Brome

POACEA

Bromus tectorum

Cheatgrass

POACEA

Buchloe dacty hides

Buffalo Grass

POACEA

Calamagrostis canadensis

Bluejoint Reedgrass

POACEA

Calamagrostis inexpansa

Northern Reedgrass

POACEA

Calamagrostis montanensis

Plains Reedgrass

POACEA

Calamagrostis stricta

Narrow- spiked Reedgrass

POACEA

Calamovilfa longifolia

Prairie Sandreed

POACEA

Callitriche hermaphroditic a

Autumnal Water-starwort

CALLIT

Callitriche heterophylla

Bolander's Waterstarwort

CALLIT

Callitriche palustris

Spring Water-starwort

CALLIT

Callitriche verna

Spring Water-starwort

CALLIT

Calochortus nuttallii

Sego-Hlly

LILIAC

Calylophus serrulatus

Plains Yellow Primrose

ONAGRA

Calystegia sepium

Hedge Bindweed

CONVOL

Camelina microcarpa

Smallseed False Flax

BRASSI

Campanula parryi

Parry's Bellflower

CAMP AN

Campanula rapunculoides

Creeping Bellflower

CAMP AN

Campanula rotundifolia

Harebell

CAMP AN

Capsella bursa-pastoris

Shepherd's Purse

BRASSI

Caragana arborescens

Caragana

FABACE

Cardaria draba

Hoary Cress

BRASSI

J -4

Flora of Sheridan County

Scientific Name

Common Name

Origin

Family Code

Carex aquatilis

Water Sedge

CYPERA

Carex atherodes

Awned Sedge

CYPERA

Carex athrostachya

Slender-beaked Sedge

CYPERA

Carex aurea

Golden Sedge

CYPERA

Carex brevior

Short-beaked Sedge

CYPERA

Carex cusickii

Cusick's Sedge

CYPERA

Carex deweyana

Dewey's Sedge

CYPERA

Carex douglasii

Douglas's Sedge

CYPERA

Carex duriuscula

Narrow-leaved Sedge

CYPERA

Carex eburnea

Ivory Sedge

CYPERA

Carex eleocharis - see C. duriuscula

Carex exsiccata

Inflated Sedge

CYPERA

Carex filifolia

Thread-leaved Sedge

CYPERA

Carex heliophila - see C. inops

Carex inops

Sun sedge

Carex laeviconica

Smooth Sedge

CYPERA

Carex lanuginosa

Woolly Sedge

CYPERA

Carex nebrascensis

Nebraska Sedge

CYPERA

Carex oederi - see C. viridula ssp viridula

Carex parry ana

Parry's Sedge

CYPERA

Carex pensylvanica

Penn's Sedge

CYPERA

Carex praegracilis

Clustered Field Sedge

CYPERA

Carex praticola

Meadow Sedge

CYPERA

Carex rossii

Ross Sedge

CYPERA

Carex sprengelii

Sprengel's Sedge

CYPERA

Carex stenophylla - see Carex duruiscula

Carex synchnocephala

Many-headed Sedge

CYPERA

Carex utriculata

Beaked Sedge

CYPERA

Carex vesicaria var monile

Inflated Sedge

CYPERA

Carex vesicaria var vesicaria

Inflated Sedge

CYPERA

Carex viridula ssp viridula

Green Sedge

CYPERA

Castilleja sessiliflora

Downy Painted-cup

SCROPH

Catabrosa aquatica

Brookgrass

POACEA

Celastrus scandens

American Bittersweet

CELAST

Centaurea maculosa

Spotted Knapweed

ASTERA

Centaurea repens

Russian Knapweed

ASTERA

Centunculus minimus

Chaffweed

PRIMUL

Cerastium arvense

Field Chickweed

CARYOP

Ceratoides lanata

Winterfat

CHENOP

Ceratoides lanata - see Krascheninnikovia

lanata

Ceratophyllum demersum

Homwort

CERATO

J -5

Flora of Sheridan County

Scientific Name

Common Name

Chaenactis douglasii
Chamaerhodos erecta
Chenopodium album
Chenopodium desiccatum
Chenopodium leptophyllum
Chenopodium pratericola
Chenopodium subglabrum

Chrysopsis villosa - see Heterotheca villosa

Origin Family Code

Hoary Chaenactis

ASTERA

Chamaerhodos

ROSACE

Common Lambsquarters

CHENOP

Desert Goosefoot

CHENOP

Slimleaf Goosefoot

CHENOP

Slimleaf Goosefoot

CHENOP

Smooth Goosefoot

CHENOP

Chrysothamnus nauseosus ssp graveolens Rubber Rabbitbrush

Chrysothamnus nauseosus ssp nauseosus

Chrysothamnus nauseosus var petrophilus

Cicuta douglasii
Cicuta maculata
Cinna arundinacea
Cinna latifolia
Cirsium arvense
Cirsium canescens
Cirsium flodmanii
Cirsium pulcherrimum
Cirsium undulatum
Clematis ligusticifolia
Cleome serrulata
Collomia linearis
Comandra pallida
Comandra umbellata
Conringia orientalis

Convoluvus sepium - see Calystegia sepium

Convolvulus arvensis
Conyza canadensis
Corallorhiza striata
Coreopsis tinctoria
Cornus stolonifera
Corydalis aurea
Coryphantha missouriensis
Coryphantha vivipara
Crataegus chrysocarpa
Crepis atribarba
Crepis modocensis
Crepis occidentalis

Rubber Rabbitbrush

Douglas Water-hemlock
Spotted Water-hemlock
Woodreed
Drooping Woodreed
Canada Thistle
Platte Thistle
Flodman's Thistle
Prairie Thistle
Wavy-leaved Thistle
Western Virgins-bower
Rocky Mountain Bee Plant
Narrow-leaf Collomia
Pale Bastard Toad-flax
Bastard Toad-flax
Mustard Hare's Ear

Field Bindweed
Horseweed
Striped Coral-root
Plains Coreopsis
Red-osier Dogwood
Golden Corydalis
Nipple Coryphantha
Pincushion Cactus
Yellow-fruit Hawthorn
Slender Hawksbeard
Low Hawksbeard
Western Hawksbeard

ASTERA

APIACE

POACEA

ASTERA

RANUNC

CAPPAR

POLEMO

SANTAL

BRASSI

CONVOL

ASTERA

ORCHID

ASTERA

CORNAC

FUMARI

CACTAC

ROSACE

ASTERA

J -6

Flora of Sheridan County

Scientific Name

Common Name

Origin Family Code

Crepis occidentalis
Crepis runcinata
Cryptantha celosioides
Cryp tanthafendle ri
Cryptantha minima
Cryptantha spiculifera
Cryptantha torreyana
Cuscuta coryli
Cuscuta pentagona
Cuscuta umbrosa
Cycloloma atriplicifolium
Cymopterus acaulis
Cymopterus terebinthinus
Cyperus schweinitzii
Cystopteris fragilis
Dalea Candida
Dalea enneandra
Dalea purpurea
Dalea villosa
Danthonia californica
Datura stramonium
Delphinium bicolor
Deschampsia cespitosa
Descurainia pinnata
Descurainia richardsonii
Descurainia sophia
Disporum trachycaulum
Distichilis stricta - see D. spicata
Distichlis spicata
Dodecatheon pulchellum
Draba micrantha
Draba nemorosa
Draba reptans
Dyssodia papposa
Echinacea angustifolia
Echinacea pallida
Echinochloa crus-gallii
Echinochloa muricata
Echinocystis lobata
Elaeagnus angustifolia
Elaeagnus commutata
Eleocharis acicularis
Eleocharis calva

Western Hawksbeard

ASTERA

Meadow Hawksbeard

ASTERA

Northern Cryptantha

BORAGI

Fendler's Cryptantha

BORAGI

Annual Cryptantha

BORAGI

Bristly Cryptantha

BORAGI

Torrey's Cryptantha

BORAGI

Hazel Dodder

CUSCUT

Five-angled Dodder

CUSCUT

Gronovius' Dodder

CUSCUT

Tumble Ringwing

CHENOP

Plains Cymopterus

APIACE

Turpentine Cymopterus

APIACE

Schweinitz's Flatsedge

CYPERA

Brittle Bladder-fern

POLYPO

White Prairie-clover

FABACE

Nine-anther Prairie-clover

FABACE

Purple Prairie-clover

FABACE

Silky Prairie-clover

FABACE

Timber Oatgrass

POACEA

Thorn Apple

SOLANA

Little Larkspur

RANUNC

Tufted Hairgrass

POACEA

Western Tansymustard

BRASSI

Richardson's Tansymustard

BRASSI

Flixweed

BRASSI

Fairy-bell

LILIAC

Alkali Saltgrass

POACEA

Few-flowered Shooting Star

PRIMUL

Carolina Whitlow-grass

BRASSI

Woods Draba

BRASSI

Carolina Whitlow-grass

BRASSI

Fetid Marigold

ASTERA

Pale Purple Coneflower

ASTERA

Pale Purple Coneflower

ASTERA

Large Barnyard Grass

POACEA

Pointed Barnyard-grass

POACEA

Wild Cucumber

CUCURB

Russian Olive

ELAEAG

Silverberry

ELAEAG

Needle Spike-rush

CYPERA

Common Spike-rush

CYPERA

J -7

Flora of Sheridan County

Scientific Name

Common Name

Origin Family Code

Eleocharis erythropoda
Eleocharis macrostachya
Eleocharis palustris

Eleocharis pauciflora - see £". quinqueflora

Eleocharis quinqueflora
Ellisia nyctelea
Elodea canadensis
Elymus canadensis
Elymus elymoides
Elymus lanceolatus
Elymus macounii
Elymus smithii
Elymus spicatus
Elymus trachycaulus
Elymus virginicus
Epilobium angustifolium
Epilobium ciliatum
Epilobium leptophyllum
Epilobium paniculatum
Equisetum arvense
Equisetum hyemale
Equisetum hyemale
Equisetum kansanum
Equisetum laevigatum
Equisetum praealtum
Eragrostis cilianensis
Eragrostis pectinacea
Erigeron asper
Erigeron caespitosus
Erigeron canadensis
Erigeron compositus
Erigeron divergens
Erigeron glabellus
Erigeron glabellus
Erigeron philadelphicus
Erigeron pumilus
Erigeron strigosus
Eriogonum annuum
Eriogonum flavum

Eriogonum multiceps

Reddish Spike-rush

CYPERA

Large-spike Spike-rush

CYPERA

Common Spike-rush

CYPERA

Few-flowered Spikerush

CYPERA

Nyctelea

HYDROP

Canada Waterweed

HYDROC

Canada Wildrye

POACEA

Bottlebrush Squirreltail

POACEA

Thick- spike Wheatgrass

POACEA

Macoun Wildrye

POACEA

Western Wheatgrass

POACEA

Bluebunch Wheatgrass

POACEA

Bearded Wheatgrass

POACEA

Virginia Wildrye

POACEA

Fireweed

ONAGRA

Common Willow-herb

ONAGRA

Narrow-leaved Willow-herb

ONAGRA

Autumn Willow-herb

ONAGRA

Field Horsetail

EQUISE

Common Scouring-rush

EQUISE

Common Scouring-rush

EQUISE

Smooth Scouring-rush

EQUISE

Smooth Scouring-rush

EQUISE

Common Scouring-rush

EQUISE

Stinkgras

POACEA

Purple Lovegrass

POACEA

Smooth Daisy

ASTERA

Tufted Fleabane

ASTERA

Horseweed

ASTERA

Cut-leaved Daisy

ASTERA

Spreading Fleabane

ASTERA

Smooth Daisy

ASTERA

Smooth Daisy

ASTERA

Philadelphia Fleabance

ASTERA

Shaggy Fleabane

ASTERA

Branching Daisy

ASTERA

Annual Buckwheat

POLYGO

Yellow Buckwheat

POLYGO

Few-flowered Wild

Buckwheat

POLYGO

J-8

Flora of Sheridan County

Scientific Name

Common Name

Origin Family Code

Eriogonum pauciflorum

Eriophorum angustifolium
Eriophorum polystachion
Erucastrum gallicum
Erysimum asperum
Erysimum capitatum
Erysimum cheiranthoides
Erysimum inconspicuum
Erysimum repandrum
Euphorbia cyparissias
Euphorbia esula
Euphorbia glyptosperma
Euphorbia marginata
Euphorbia missurica
Euphorbia robusta
Euphorbia serpyllifolia
Euphorbia spathulata
Eustoma grandiflorum
Euthamia occidentalis
Festuca arundinacea
Festuca octo flora
Festuca ovina
Fragaria virginiana
Fraxinus pennsylvanica
Fumaria ofl'icinalis
Gaillardia aristata
Galium aparine
Galium boreale
Galium triflorum
Gaura coccinea
Gaura parviflora
Gayophytum diffusum
Gentiana affinis
Gentianella amarella
Geum aleppicum
Geum canadense
Geum macrophyllum
Geum triflorum
Gilia conge sta
Glaux maritima
Glyceria grandis
Glyceria striata

Few-flowered Wild
Buckwheat

Many-spiked Cotton-grass
Many-spiked Cotton-grass
Dog Mustard
Plains Wallflower
Western Wallflower
Wormseed Wallflower
Smallflowered Wallflower
Spreading Wallflower
Cypress Spurge
Leafy Spurge
Corrugate- seeded Spurge
Snow-on-the-mountain
Missouri Spurge
Rocky Mountain Spurge
Thyme-leaf Spurge
Spatulate-leaved Spurge
Showy Prairie-gentian
Western Goldenrod
Tall Fescue
Six-weeks Fescue
Sheep Fescue
Virginia Strawberry
Green Ash
Common Fumitory
Blanket- flower
Goose-grass
Northern Bedstraw
Sweetscented Bedstraw
Scarlet Gaura
Small-flowered Gaura
Spreading Groundsmoke
Pleated Gentian
Northern Gentian
Yellow Avens
White Avens
Large-leaved Avens
Prairie Smoke
Ballhead Gilia
Saltwort

American Mannagrass
Fowl Mannagrass

POLYGO

CYPERA

BRASSI

EUPHOR

GENTIA

ASTERA

POACEA

ROSACE

OLEACE

FUMARI

ASTERA

RUBIAC

ONAGRA

GENTIA

ROSACE

POLEMO

PRIMUL

POACEA

J -9

Flora of Sheridan County

Scientific Name

Common Name

Origin Family Code

Glycyrrhiza lepidota
Gnaphalium palustre
Grindelia squarrosa
Gutierrezia sarothrae
Gypsophila paniculata
Habenaria hyperborea
Hackelia deflexa
Hackelia floribunda
Haplopappus armerioides
Haplopappus lanceolatus
Haplopappus lanuginosus
Haplopappus spinulosus
Hedeoma drummondii
Hedeoma hispida
Hedysarum boreale
Helenium autumnale
Helianthus annuus
Helianthus maximiliani
Helianthus nuttallii
Helianthus pauciflorus
Helianthus petiolaris
Helianthus rigidus
Helianthus tuberosus
Helictotrichon hookeri
Heliotropium curassavicum
Heracleum spondylium
Hesperis matronalis
Heterotheca villosa
Heuchera richardsonii
Hieracium canadense
Hieracium umbellatum
Hordeum brachyantherum
Hordeum jubatum
Hordeum pusillum
Humulus lupulus
Hymenopappus filifo lius
Hymenoxys acaulis
Hymenoxys richardsonii
Hyoscyamus niger
Hypericum scouleri
Ipomopsis congesta
Iva axillaris
Iva xanthifolia

American Licorice

FABACE

Lowl Cudweed

ASTERA

Curlycup Gumweed

ASTERA

Broom Snakeweed

ASTERA

Baby's Breath

CARYOP

Northern Green Bog-orchid

ORCHID

Nodding Stickseed

BORAGI

Showy Stickseed

BORAGI

Thrift Goldenweed

ASTERA

Lance-leaf Goldenweed

ASTERA

Woolly Goldenweed

ASTERA

Spiny Goldenweed

ASTERA

Drummond False Pennyroyal

LAMIAC

Rough Pennyroyal

LAMIAC

Northern Hedysarum

FABACE

Sneezeweed

ASTERA

Common Sunflower

ASTERA

Maximilan's Sunflower

ASTERA

Nuttall's Sunflower

ASTERA

Showy Sunflower

ASTERA

Prairie Sunflower

ASTERA

Showy Sunflower

ASTERA

Jerusalem Artichoke

ASTERA

Spike Oat

POACEA

Salt Hehotrope

BORAGI

Cow-parsnip

APIACEA

Dame's Rocket

BRAS SIC

Hairy Golden-aster

ASTERA

Richardson's Alumroot

SAXIFR

Canada Hawkweed

ASTERA

Narrow-leaved Hawkweed

ASTERA

Meadow Barley

POACEA

Foxtail Barley

POACEA

Little Barley

POACEA

Common Hop

CANNAB

Columbia Cut-leaf

ASTERA

Stemless Hymenoxys

ASTERA

Richardson's Hymenoxys

ASTERA

Black Henbane

SOLANA

Norton's St. Johnswort

CLUSIA

Ballhead Gilia

POLEMO

Poverty-weed

ASTERA

Tall Marsh-elder

ASTERA

J-10

Scientific Name

Flora of Sheridan County

Common Name

Origin Family Code

Juncus articulatus

Jointed Rush

JUNCAC

Juncus balticus

Baltic Rush

JUNCAC

Juncus bufonius

Toad Rush

JUNCAC

Juncus dudleyi

Dudley Rush

JUNCAC

Juncus longistylis

Long-styled Rush

JUNCAC

Juncus nodosus

Tuberous Rush

JUNCAC

Juncus tenuis

Slender Rush

JUNCAC

Juncus torreyi

Torrey's Rush

JUNCAC

Juniperus communis

Common Juniper

CUPRES

Juniperus horizontalis

Creeping Juniper

CUPRES

Juniperus scopulorum

Rocky Mountain Juniper

CUPRES

Koeleria cristata - see K. macrantha

Koeleria pyramidata

Junegrass

POACEA

Krascheninnikovia lanata

Winterfat

CHENOP

Kuhnia eupatorioides

False-boneset

ASTERA

Lactuca ludoviciana

Western Lettuce

ASTERA

Lactuca oblongifolia

Blue Lettuce

ASTERA

Lactuca serriola

Prickly Lettuce

ASTERA

Lappula cenchrusoides

Millet Stickseed

BORAGI

Lappula echinata

Europen Sticktight

BORAGI

Lappula occidentalis

Desert Stickseed

BORAGI

Lappula redowskii

Western Stickseed

BORAGI

Lemna minor

Common Duckweed

LEMNAC

Lemna trisulca

Star Duckweed

LEMNAC

Leonurus cardiaca

Motherwort

LAMIAC

Lepidium densiflorum

Prairie Pepperweed

BRASSI

Lepidium perfoliatum

Clasping Pepperweed

BRASSI

Lepidium ramosissimum

Branched Pepperweed

BRASSI

Lepidium virginicum

Tall Pepperweed

BRASSI

Leptochloa fascicularis

Loose-flowered Sprangletop

POACEA

Lesquerella alpina

Alpine Bladderpod

BRASSI

Lesquerella arenosa

Sand Bladderpod

BRASSI

Lesquerella ludoviciana

Silvery Bladderpod

BRASSI

Leucocrinum montanum

Mountain Lily

LILIAC

Liatris ligulistylis

Large-headed Gay-feather

ASTERA

Liatris punctata

Dotted Blazing-star

ASTERA

Lilium philadelphicum

Motherwort

LAMIAC

Limosella aquatica

Mudwort

SCROPH

Linaria dalmatica

Dalmatian Toadflax

SCROPH

Linum lewisii

Wild Blue Flax

LINAGE

Linum rigidum

Yellow Flax

LINAGE

Linum usitatissimum

Cultivated Flax

LINAGE

Lithospermum arvense

Corn Gromwell

BORAGI

J-11

Flora of Sheridan County

Scientific Name

Common Name

Origin

Family Code

Lithospermum incisum

Yellow Gromwell

BORAGI

Lobelia kalmii

Kalm's Lobelia

CAMP AN

Lobelia spicata

Pale-spike Lobelia

CAMP AN

Lolium persicum

Persian Darnel

POACEA

Lomatium cous

Cous Biscuit-root

APIACE

Lomatium dissectum

Fern-leaved Desert-parsley

APIACE

Lomatium foeniculaceum

Fennel-leaved Desert-parsley

APIACE

Lomatium macrocarpum

Bigseed Desert-parsley

APIACE

Lomatium orientale

Oriental Lomatium

APIACE

Lotus unifoliolatus

Spanish-clover

FABACE

Lupinus argenteus

Silvery Lupine

FABACE

Lupinus lepidus

Prairie Lupine

FABACE

Lycium halimifolium

Matrimonyvine

SOLANA

Malva parviflora

Little Mallow

MALVAC

Matricaria matricarioides

Pineapple Weed

ASTERA

Medicago lupulina

Black Medic

FABACE

Medicago sativa

Alfalfa

FABACE

Melilotus alba

White Sweetclover

FABACE

Melilotus officinalis

Yellow Sweetclover

FABACE

Mentha spicata

Spearmint

LAMIAC

Microseris nutans

Nodding Microseris

ASTERA

Monotropa uniflora

Indian Pipe

ERICAC

Nepeta cataria

Catnip

LAMIAC

Oenothera serrulata - see Calylophus

serrulatus

Oxalis dillenii

Dillen's Wood-sorrel

OXALID

Oxytropis campestris var gracilis - see 0.

monticola

Petalostemum spp. - see Dalea spp.

Phalaris arundinacea

Reed Canary grass

POACEA

Poa palustris

Fowl Bluegrass

POACEA

Poa pratensis

Kentucky Bluegrass

POACEA

Poa trivialis

Roughstalk Bluegrass

POACEA

Polygonum convolvulus

Black Bindweed

POLYGO

Polygonum lapathifolium

Willow Weed

POLYGO

Polygonyum coccineum - see P. amphibium

Potamogeton gramineus

Potentilla fruticosa - see Pentaphylloides

floribunda

Psoralea lanceolata - see Psoralidium

lanceolatum

Grass-leaved Pondweed

POTAMO

J-12

Flora of Sheridan County

Scientific Name

Common Name

Origin Family Code

Ranunculus gmelinii

Rhamnus cathartica

Rosa acicularis - see R. sayi

Rumex acetosa

Rumex crispus

Ruppia maritima

Salsola collina

Salsola iberica

Scirpus microcarpus

Scolochloa festucacea

Setaria viridis

Silene cserei

Sisymbrium altissimum

Sonchus arvensis

Sonchus asper

Sonchus uliginosus

Spergularia marina

Sphenopholis obtusata

Spirodela polyrhiza

Stellaria media

Stipa curtiseta

Stipa spartea var. curtiseta - see Stipa

curtiseta

Stipa viridula - see Nasella viridula

Suaeda depressa - see 5". calciformis

Tanacetum vulgare

Taraxacum officinale

Thlaspi arvense

Tragopogon dubius

Trifolium pratense

Trifolium repens

Triodanis perfoliata

Ulmus pumila
Vaccaria pyramidata
Verbascum blattaria
Verbena hastata
Zygophyllum fabago

Small Yellow Water-buttercup

RANUNC

European Buckthorn

RHAMNA

Meadow Sorrel

POLYGO

Curly Dock

POLYGO

Wigeon-grass

RUPPIA

Slender Russian Thistle

CHENOP

Russian Thistle

CHENOP

Small-flowered Bulrush

CYPERA

Whitetop

POACEA

Green Foxtail

POACEA

Smooth Catchfly

CARYOP

Tall Tumbleustard

BRASSI

Perennial Sowthistle

ASTERA

Sping Sowthistle

ASTERA

Marsh Sowthistle

ASTERA

Salt-marsh Sandspurry

CARYOP

Slender Wedgegrass

POACEAE

Greater Duckweed

LEMNAC

Chickweed

CAROPHY

Northern Porcupinegrass

POACEAE

Common Tansy
Common Dandelion
Field Pennycress
Goatsbeard
Red Clover
White Clover

Western Venus'-looking-glass

Siberian Elm
Cowcockle
Moth Mullein
Blue Verbena
Bean Caper

ASTERA

BRASSI

ASTERA

FABACE

CAMP AN

ULMACE

CARYOP

SCROPH

VERBEN

ZYGOPH

J-13

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Full text of "Plant species of special concern and plant associations of Sheridan County, Montana"

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