Range- wide Status Assessment

of Cirsium longistylum

(long-styled thistle)

Prepared for:
Burnett Land, LLC

By:
Scott Mincemoyer

Montana Natural Heritage Program

Natural Resource Information System

Montana State Library

December 2004

MONTANA

Natural Hedtage
Prcgiam ^

Range- wide Status Assessment

of Cirsium longistylum

(long-styled thistle)

Prepared for:

Burnett Land, LLC

Contract Number:
20040504

By:

Scott Mincemoyer

TState
Libr;

rary

unnXhli h

Natural I4eGtage
Piugram

W|W Information Syi^tieni

© 2004 Montana Natural Heritage Program

P.O. Box 201800 • 1515 East Sixth Avenue • Helena, MT 59620-1800 • 406-444-5354

This document should be cited as follows:

Mincemoyer, S. 2004. Range-wide Status Assessment of Cirsium longistylum (long-styled thistle).
Report to Burnett Land, LLC. Montana Natural Heritage Program, Helena, MT. 22 pp. + appendices.

Executive Su m m a r y

Cirsium longistylum Moore & Frankton (long-
styled thistle) is a state endemic thistle restricted to
areas of central Montana in and around the Little
Belts, Big Belts and Castle mountains, generally on
sedimentary parent materials. First described as a
distinct species in 1963, its overall distribution and
abundance remained poorly documented for a
couple decades afterwards. It is currently known
from a six county area. The majority of the
populations occur on National Forest lands
managed by the Helena and Lewis and Clark
National Forests, though a few populations occur
partially or wholly on private lands.

Field surveys were initiated in 2004 to update
occurrence and population data for the species.
These surveys discovered several new populations,
extended the boundaries of several others, failed to
relocate a few occurrences and provided updated
and more precise population estimates for most of
the known occurrences. Additional data and field
observations were collected that enabled us to
clarify potential threats such as those posed by

invasive weeds and an introduced bio-control
Rhinocyllus conicus.

Population estimates of nearly 30,000 plants,
including seven high quality populations, scattered
over four mountain ranges are promising for the
long-term viability of the species. Long- and
short-term population trends are difficult to gauge
due to the lack of good survey data over many
years. How^ever, available data and observations
provide some evidence that population levels have
at least remained fairly stable over the past
decade, w^ith significant yearly fluctuations
possible. Threats posed by invasive w^eeds and
the introduced bio-control provide reason for
concern and population monitoring should
continue in the future. As a result of this
assessment, the Montana Natural Heritage
Program ranking of the species will change from
the current G2/S2 to G3/S3 (see Appendix A:
Global/State Rank Definitions).

m

Acknowledgements

This assessment was made possible by funds from providing many valuable insights. Cobum Currier

Burnett Land, LLC and the 6666 Ranch. Drake attended to the final layout and production. Special

Barton conducted much of the survey work in 2004 thanks to Bryan Douglass and Bruce Goldberg for

and also in 2001 on the Helena National Forest and providing logistical support. Many other individuals

provided valuable background information. Thanks provided useful information and help. They include

to Cathy Seibert at Montana State University for Steve Shelly, Steve Cooper, Wayne Phillips and the

providing specimen information and allowing entire staff at the Montana Natural Heritage

examination of herbarium specimens. Thanks to Program.
Kathy Lloyd for reviewing the document and

IV

Tableof Contents

Introduction 1

Species Information 2

Classification 2

Present Legal or Other Formal Status 2

Description 2

Geographic Distribution 4

Habitats 13

Land Owemership 14

Potential Threats to Known Populations 15

Assessment and Recommendations 18

General Assessment of Trends and Status 18

Status Recommendation 20

Literature Cited 21

Appendix A: Global/State Rank Definitions

Appendix B: Element Occurrence Rank Definitions

Appendix C: Element Occurence Maps for Cirsium longistylum

LiSTOF Figures

Figure 1. Cirsium longistylum flower head 3

Figure 2. Putative hybrid between C. longistylum and C. hookerianum in the Dry Range 3

Figure 3. Cirsium hookerianum flower head 3

Figure 4. Occurrences of Cirsium longistylum (Extant and Historical EO' s) 5

Figure 5. Cirsium longistylum habitat in the Dry Range 14

Figure 6. Cirsium longistylum habitat and flowering plants near Spur Park after fire 14

Figure 7. Rhinocyllus conicus weevils on C longistylum in the Little Belt Mountains 15

Figure 8-9. Grazing impacts on Cirsium longistylum 17

Figure 10. Permanent monitoring plot (15' radius) near Kings Hill, Little Belt Mountains 18

Figure 11. Permanent monitoring plot (37' radius) near Russian Creek, Little Belt Mountains 18

Figure 12. Permanent monitoring plot (15' radius) near Neihart, Little Belt Mountains 19

List OF Tables

Table 1. Element Occurrence Records for Cirsium longistylum 8

Table 2. Ranking factors and assigned scores for the C longistylum assessment 19

I. Introduction

Cirsium longistylum Moore & Frankton (long-
styled thistle) is a state endemic thistle restricted to
areas of central Montana in and around the Little
Belts, Big Belts and Castle mountains, generally on
sedimentary parent materials. First described as a
new species in 1963 by Moore and Frankton, its
overall distribution and abundance remained poorly
documented for a couple decades afterwards.
Starting in the 1980's the U.S. Forest Service and
the Montana Natural Heritage Program (MTNHP)
began to document populations of the thistle,
primarily in the Little Belt Mountains. Surveys
from the 1980' s to 2001 substantially increased the
knowledge of the distribution and abundance of the
species. During this time, the documented range
was extended into the Big Belts and Castle
Mountains and in 2003 it was documented in the
Dry Range between the Little Belts and Big Belts.

In 1990 the U.S. Fish and Wildlife Service included
the species in its listing of candidate species for
federal protection under the Endangered Species
Act (U.S. Department of Interior 1990). After
review it was determined that the species did not
warrant protection under the Act. However,
threats to the species from several sources and its
limited distribution did raise concern about the
species' long-term viability and it continued to be
tracked in the state by the MTNHP. MTNHP has
maintained and collected occurrence and population
data on the species for several decades.

The purpose of this assessment is to collect updated
survey data on the range-wide distribution and
abundance of the species, identify threats, assess
trends and review and update the species ranking in
the state as appropriate.

II. Species Information

A. Classification

1. Scientific Name: CirsiumlongistylumMoovt
& Frankton

2. Common Name: long-styled thistle, longstyle
thistle

3. Family: As teraceae (aster or sunflower family);
in the tribe Cardueae

4. Type Description and Specimens Cited:
Moore, RJ. and C. Frankton. 1963.
Cytotaxonomic notes on some Cirsium species of
the western United States. Canadian Journal of
Botany. 41:1553-1567.

Senn, Frankton & Gillett 5666, Aug. 23, 1951.
Montana, Cascade Co., Little Belt Mountains, 3
miles SE of Monarch (Holotype: DAO)
Senn, Frankton & Gillett 5670, Aug. 23, 1951.
Montana, Meagher Co., Kings Hill, 8000 ft. (DAO)
Senn 6207, Jul. 29, 1953. Montana, Meagher Co.,
Little Belt Mountains, 20 miles south of Neihart,
Forest Green Resort, 5600 ft. (DAO)
Flodman 880, Aug. 19, 1896. Montana, Long
Baldy, Little Belt Mountains. (NY)

Herbarium reference codes are from Holmgren and
Holmgren (1990).

5. Size of Genus: Cirsium is a diverse genus with
13 species in Montana (Dom 1984, USDA NRCS
2004), approximately 101 species in the United
States (USDA NRCS 2004) and approximately 350
species worldwide (Moore and Frankton 1974).

B. Present Legal or Other Formal
Status

L National

a. Legal Status: The species was considered for
protection under the Endangered Species Act (U.S.
Department of Interior 1990) in the early 1990's but

was dropped from consideration after additional
survey data showed that it did not warrant
protection under the Act.

2. State

a. Montana

i. Legal Status: None.

ii. Heritage Rank: The current (prior to this status
assessment) state rank is S2, indicating that it is at
high risk due to potentially declining population
numbers and/or habitat, making it vulnerable to
extinction or extirpation in the state.

C. Description

L General Non-technical Description: Long-
styled thistle has simple or branched stems that are
50-60 cm tall and up to 15 mm thick at the base;
plants are perennial, producing daughter rosettes
that live for two more years. The basal leaves are
shallowly lobed, moderately spiny, green and
glabrous above, and densely white-hairy below; the
lower leaves are narrowly lance-shaped, up to 15
cm long, and lobed to 1/3 or less the leaf width.
The smaller upper leaves are more ovate in outline
with mostly entire margins and numerous marginal
spines; the herbage is covered with long, tangled,
white hairs. The inflorescence usually consists of a
terminal cluster of 2 to several flower heads and a
number of side branches that reach up to 15 cm
long and have fewer heads; each flower head is
about 30 mm high, 25 mm wide, and subtended by a
few reduced leaves. The involucral bracts occur in
two main series: the outer are narrowly lance-
shaped with a yellowish, dilated, and fringed apex
tipped by a slender spine; the inner bracts are more
lance-shaped and longer. The white disk flowers
are 20-22 mm long; ray flowers are absent. There
are numerous tawny bristles, which form a pappus
at the tip of the achene.

2. Technical Description: Plants 50-60 cm high,
stems thick, to 1.5 cm diameter at the base, ribbed,
lightly arachnoid pubescent with long, multicellular
hairs; perennial with biennial to perennial offsets.

Leaves linear-lanceolate, base not decurrent, length
about 10 times the width, to 15 cm long, 1.5 cm
wide, lobed to 1/3 width, or less, the smaller upper
leaves essentially entire, lobes ovate, often irregular
with numerous fine marginal spines to 5 mm long.
Leaves gray-green, lightly arachnoid above, white,
villous below. Flower heads 3 cm high, 2.5 cm
wide. Arrangement of heads variable and not
exclusively in a close terminal cluster, but also
borne one or two at the apex of the stem and on
lateral branches. Plants usually bearing many
floriferous branches to 15 cm long on the terminal
third of the stem. Heads are subtended by a few
reduced leaves, the uppermost about the same size
as the involucral bracts with gray multi-cellular
hairs at right angles to the margin. Involucre 2 cm
high, composed of five to six rows of phyllaries.
Outer phyllaries linear-lanceolate, base 1.5-2 mm
broad, weakly glandular or with a dark blotch,
surface glabrous, apical portion slightly dilated with
a yellow lacerate fringe, tipped by a slender 2 mm
spine. Middle phyllaries similar but progressively
less dilated-lacerate. Inner phyllaries longer,
lanceolate, tip not or only slightly dilated and
lacerate. Flowers white, corolla 20-22 mm long,
tube 7-9 mm, lobes 3.5-5.5 mm, pappus 18-19 mm,
tawny with 30-40 setae, longer setae clavellate;
anthers, including appendages 7.5-8.5 mm long, free
anther tips usually incurved; pollen 44-5 1 |li in outer
diameter; style long exserted to 1 cm beyond the
corolla, tip to joint of style 3.5-5 mm. Achenes 5.5-
6.5 mm x 2 mm, light brown, sometimes with
purplish flecks. Rosette leaves moderately spiny.

the margins with broad, shallow divisions, green and
glabrous above, densely white pubescent below
(Moore and Frankton 1963).

Figure 2. Putative hybrid between C. longistylum and C.
hookerianum in the Dry Range. Note the slightly
widened involucral bracts.

3. Similar Species: Cirsium hookerianum and C.
scariosum are both similar to C longistylum in
terms of their overall morphology and biology. In
addition, the geographic distribution and habitats of
the species overlap. C. hookerianum can be
distinguished by its long-tapering involucral bracts
that are not fringed and dilated near the apex.
Specimens of C scariosum may be confused with

Figure 1 . Cirsium longistylum flower head. Note the
widened and fringed involucral bracts.

Figure 3. Cirsium hookerianum flower head. Note the
long-tapering involucral bracts.

C. longistylum in that the inner involucral bracts
are sometimes fringed and dilated at the apex.
However, the outer involucral bracts always taper
to the tip without a fringed or dilated section. In
fact, the reported occurrence of C longistylum in
the Elkhom Mountains (Poole and Heidel 1993)
was apparently based on specimens of C
scariosum with apically fringed and dilated inner
involucral bracts intermixed with C hookerianum
(Mincemoyer 2004). Confusion among the taxa
arises due to apparent hybridization and
introgression among the species which results in
intermediate bract characteristics. Currently,
identification of rosettes and vegetative specimens
based on morphological characters alone cannot be
reliably determined.

4. Phylogenetic Relationships: Cirsium
longistylum is closely related to other members of
the genus, such as C hookerianum and C
scariosum. Chromosome counts of the 3 species
are all 2n=34 (Mathews 1980, Moore and Frankton
1963, Ownbey and Hsi 1963, Gardner 1974).
Results of a genetic analysis by Brunsfeld and
Baldwin (1994) provided additional evidence that C.
longistylum is a distinct species and actually
appears to be the most genetically distinct of the 3
species studied in west-central Montana. However,
C longistylum appears to commonly hybridize with
the former and probably the latter as well. Based
on bract morphology, putative hybrids with C.
hookerianum appear to be common in areas
where the two species are in close proximity,
though enzyme electrophoresis found that the
putative hybrids were most closely related to "pure"
C. longistylum (Brunsfeld and Baldwin 1994).
Also of interest is the fact that samples of C.
hookerianum and C scariosum taken from
outside Montana were genetically distant from

samples of the same species taken from within the
state, based on an analysis of randomly amplified
polymorphic DNA (RAPD) (Brunsfeld and
Baldwin 1994). This suggests that introgression
among the species may have historically occurred
in the region and that gene flow among the species
is likely still taking place.

D. Geographic Distribution

1. Range: C longistylum is a state endemic
thistle restricted to areas of central Montana in and
around the Little Belts, Big Belts and Castle
mountains, generally on sedimentary parent
materials. Currently, the known distribution of the
species is centered in the Little Belt Mountains,
with additional populations in the Big Belts, Castle
Mountains and the Dry Range. Populations also
occur in the valley between the Little Belts and the
Castle Mountains. The first known collection of the
species was by Flodman in 1896 in the Little Belt
Mountains. However, the plant was not formally
described and recognized as a new species until
1963 (Moore and Frankton 1963) so the species
went largely un-noticed for another 70 years after
its first known collection. The species was known
only from the Little Belts until 1976 when it was
collected in the Big Belts by Robert Dom
(specimen deposited at MONT), though further
surveys in the Big Belts did not take place until
1983. Its range was further extended into the
Castle Mountains with a collection by Dana Field in
1991 and subsequent field surveys in 1992. Finally,
in 2003 it was documented in the Dry Range
between the Big Belts and the Little Belts (Olsen
2003). This brings the current known range to six
counties, not including a historical collection from
the Big Snowies.

Figure 4. Occurrences of Cirsium longistylum (Extant and Historic EO's)

2. Historical Populations: A survey of the
Montana State University Herbarium (MONT) in
2004 located one specimen from the Big Snowy
Mountains:

Booth 60121. July 19, 1960. Fergus Co., Snowy
Mtns., about 20 miles south of Lewistown.

This specimen appears to be "pure" C. longistylum
or a putative hybrid leaning towards C
longistylum. Limited surveys in the Big Snowy
Mountains in August and September of 2004 could
not relocate this population or any C longistylum
in the area. Unfortunately, the label information
with this specimen is vague in regards to the
collection locality and population size. The only
native thistle species observed in the range was C
eatonii (Gray) Robins., which was locally abundant
from lower elevation dry streambeds to the crest of
the range. The geology and habitats found in the
Big Snowies appear suitable for supporting
populations of C longistylum and additional future
surveys may document the species in the area.

Data for five additional historical occurrences or
populations that could not be relocated in 2004 are
also maintained by the Montana Natural Heritage
Program. These occurrences are described in
Table 1.

Past reports of the species from the Elkhom
Mountains (Poole and Heidel 1993) appear to be in
error and were based on mis-identification of C
scariosum. Field surveys to the site in 2004 by
Mincemoyer were unable to locate any C
longistylum in the area, however the site does
support a large population of C hookerianum with
minor amounts of C scariosum. This is actually
supported by the data collected in 1992 that states
"Only 1 plant, in fruit, with C. longistylum
characters was observed among a population of
approximately 100 plants of C. hookerianum and
possible hybrids and backcrosses." The specimens
of C. scariosum examined at the site generally
have inner involucral bracts dilated and fringed at
the apex with outer bracts tapered to the tip. This
probably led to the confusion in the identification of
the species. In addition, the parent material of the

site is generally granitics, while C. longistylum is
typically found on calcareous substrates.

3. Additional Survey Areas: Mapping of suitable
habitat for C. longistylum using ArcGIS and layers
of geology, soils and precipitation was done to
identify potential survey areas for 2004.
Preliminary mapping identified several suitable
areas in the Big Snowies, Elkhoms and Judith
mountains, in addition to the mountain ranges
already known to support populations of C.
longistylum. Field surveys to several of the areas
in the Elkhom Mountains with potential suitable
habitat failed to find any C. longistylum. However,
the native thistles C. hookerianum and C.
scariosum were encountered. Limited surveys in
the Judith Mountains also failed to locate any C.
longistylum. Other areas that have been surveyed
in past years without any success include the
Highwood Mountains and areas near Homestake
Pass west of Helena.

4. Extant Sites: Occurrences of C. longistylum
are summarized in Table 1 and Figure 4. Detailed
occurrence maps are provided in Appendix C. The
seven largest and highest quality (A or AB ranked)
populations are described in further detail below.

The Kings Hill (EO #2) site was first observed in
1951, though details of the population were not
documented until 1986. This is the largest known
occurrence with 2004 surveys estimating the
population at 9500+ individuals. This population
extends across approximately 2000 acres on
elevations of 6400-8100 feet. Populations extend
from Kings Hill Pass and Showdown Ski area east
and southeast to the Spur Park and Ant Park areas
and south along portions of Deadman Creek.
Habitats include subalpine and montane meadows,
open subalpine forests and roadsides. In the Ant
Park area, the thistle responded positively to a
previous fire with many flowering individuals visible
from the road in 2004. Very few weeds are
currently present in this population though minor
amounts of Cirsium arvense (Canada thistle),
Cynoglossum officinale (houndstongue) and
Phleum pratense (common timothy) were noted in
2004. Dominant vegetation is variable across the

area but includes species such as Festuca
idahoensis (Idaho fescue), Potentilla fruticosa
(shrubby cinquefoil), Danthonia intermedia
(intermediate oatgrass), Stipa nelsonii (Nelson's
needlegrass) and Potentilla gracilis (slender
cinquefoil). Small numbers of C. hookerianum
and putative hybrids were noted in the area, though
overall this population appears to be mostly "pure"
C. longistylum. A large population of C.
hookerianum occurs several miles to the west in
the Moose Park and O'Brien Park areas and it
seems likely that gene flow between these two
populations is occurring.

The Duck Creek Pass (EO #6) site in the Big Belt
Mountains was estimated at 1200 plants during a
2004 survey. Previous estimates of population size
were imprecise, with a 1992 survey placing the
population between 1000-5000 individuals. The
population covers approximately 200 acres and
extends from near Gypsy Lake to approximately 2
miles west of Duck Creek Pass with the largest
concentration of plants near the pass. The best and
most intact habitat for the species occurs in the
subalpine and montane meadows near the pass and
immediately to the west. Several non-native
species are present at the site, particularly at lower
elevations. Phleum pratense is abundant while
Agrostis stolonifera (bentgrass) and Bromus
inermis (smooth brome) are locally common. Also
present in the area are Cirsium arvense, Cirsium
vulgare (bull thistle) and Carduus nutans (musk
thistle). In spite of the threats posed by non-native
species at the site, this is the most intact population
within the Big Belt Mountains.

The Russian Flat (EO #20) site is the second
largest population in the Little Belt Mountains with
an estimate of 2000 individuals in 2004 over an area
of about 700 acres. This population was first
observed in 1990 with survey information noting
"thousands of plants" in the area. Plants are
concentrated in the meadows of Russian Flat, along
Russian Creek and in meadows west of Russian
Creek and south of Forest Service Road 487.
However, individual plants are scattered along the
road from approximately 2 miles east of Russian
Flat to Hoover Spring along the South Fork Judith
River about 6 miles west of Russian Flat. Though

native vegetation dominates the area, several non-
native species occur throughout the area, including
Phleum pratense, Cirsium vulgare, Bromus
inermis, Cynoglossum officinale and Carduus
nutans.

The Atlanta Creek (EO #23) population occurs in
the central Big Belts with an estimated population
of 1000 individuals in 2004. The population occurs
along Atlanta Creek and the open ridge to the north
in section 6 at elevations of 6400-7400 feet. This
area was first surveyed in 1992 and the population
was documented at 250-400 plants over a 40 acre
area. Of the 7 largest populations described here in
detail this one may have the highest population
density of C longistylum. Putative hybrids occur
at the site, though only account for approximately
15% of the Cirsium plants in the area. The site is
dominated by native vegetation with small amounts
of Bromus inermis and Phleum pratense.

The Dry Range (EO #56) population is a new site
first documented in 2003 in montane meadows and
open forests from 5000-6200 feet elevation. The
site is approximately 20 miles northwest of White
Sulphur Springs and occurs on a mix of private and
National Forest lands. Surveys in 2004 estimated
the population at approximately 2200 plants, along
with numerous putative hybrids with Cirsium
hookerianum. Density of C. longistylum tends to
be highest near the crest of the range and on upper,
south-facing slopes and declines quickly with
decreasing elevation. The 2004 survey mapped
occupied areas totaling approximately 790 acres.
The 2003 estimate of 10,000 plants was too high
due to inclusion of unsuitable habitat and putative
hybrids. This population occurs in high quality
montane meadows dominated by Stipa
richardsonii, (Richardson's needlegrass) Festuca
scabrella (rough fescue) and Festuca idahoensis
with a diverse and abundant forb component.
Several non-native species occur throughout the
survey area with Bromus inermis and Phleum
pratense being locally abundant in several disturbed
meadows. The introduced bio-control agent
Rhinocyllus conicus was observed in
approximately 80% of the flower heads that were
examined, with significant reductions in mature
seeds. However, later developing flower heads

were largely uninfested since their development did
not coincide with of the development of the weevil.

The East Fork Checkerboard Creek (EO #36) site
is the largest documented population in the Castle
Mountains with an estimated 1200 plants. C.
longistylum was first observed in the area in 1992.
The currently documented population extends from
the headwaters of the East Fork Checkerboard
Creek along FS Road 211, southeast along the
South Fork Bonanza Creek and FS Road 581, north
along Limestone Ridge and to the east along FS
Road 585. Occupied habitats include riparian
grasslands, montane meadows and several miles of
roadsides at elevations of 6500-7000 feet. The
area occupied by this population is approximately 80
acres. Species composition varies across the
population, though dominants include Festuca
idahoensis, Poa pratensis and Koeleria
macrantha (prairie junegrass). Non-natives in the
area include Cirsium arvense, Cynoglossum
officinale, and Bromus inermis.

The Forest Service Road 274 (EO #68) population
is a new occurrence documented in 2004. It occurs
in the Little Belt Mountains and extends from
Elephant Rock north for approximately 7 miles.
Another significant subpopulation occurs in Bear
Park about 3 miles north-northeast of Elephant
Rock. Surveys in 2004 documented a population
between 1000-1200 plants covering an area of
almost 250 acres. The majority of the population
occurs adjacent to roads, though significant
numbers of plants occur in montane meadows
dominated by Festuca scabrella, Festuca
idahoensis, Koeleria macrantha. Geranium
viscosissimum (sticky geranium), Artemisia
tridentata (big sagebrush) and Potentilla gracilis.
Exotic species associated with this occurrence
include Bromus inermis, Cirsium arvense and
Phleum pratense.

Table 1 . Element Occurrence Records for Cirsium longistylum. See Appendix B for a description of the ranking
codes.

E0#

County

Survey Site

Survey Data

Description

Ranking

01

Cascade

Monarch SE. Approximately 3
miles SE of Monarch.

No population data. Type locahty,
collected in 1951. Last observation in
1983.

4820-4920 ft.

H

02

Cascade,

Meagher,

Judith Basin

Kings Hill. Little Belt Mountains,
King's Hill Pass and Showdown
Ski area east and southeast to the
Spur Park and Ant Park areas and
south along portions of Deadman
Creek.

2004: 3 large subpops. surveyed: with
approx 9,500 plants. 1992: About
2200 plants in 2 surveyed subpops.,
concentrated around Kings Hill. None
in campground, few along road or in
ski area. 1990: Extended population
boundaries, tens of thousands of
plants. 1986: Frequent.

6400-8100 ft.
Roadsides,
meadows.

A

03

Meagher

Forest Green. About 16 miles
south of Neihart.

1992 survey estimated 100 Cirsium
plants with <10% showing
characteristics of C. longistylum. First
observation in 1953.

6030-6040 ft.
Meadow.

C

04

Cascade

Monarch. Approximately 1 mile
east of Hwy . 89 on Dry Fork Road

(#120).

2004: plants. 1992: plants.1986: 2
plants observed.

4822 ft.
Roadsides,

disturbed
grasslands.

F

05

Cascade

Bender Creek Trail. Little Beh
Mountains, 9.7 miles east of
Monarch on FS Road #120 (Dry
Fork Belt Creek Road); population
is at junction of road with trail
#318 (Bender Creek Trail).

2004: Resurvey of the site found no C.
longistylum. C. hookerianum and
hybrids present. 1994: >100 flowering
plants & rosettes. 1992: 23 plants, 18
flowering, 3 of which were C.
longistylum. 1990: 10 plants counted.
1986: 20 plants; evidence of possible
hybridization with C. hookerianum.

4680-5360 ft.

Meadows,

roadsides,

riparian areas,

disturbed sites.

F

Table 1. Continued.

E0#

County

Survey Site

Survey Data

Description

Ranking

06

Broadwater,
Meagher

Duck Creek Pass. Big Belt

Mountains, Duck Creek Pass Road
#139, beginning just west of turnoff
to Thompson Gulch guard station
and Gipsy Lake area, and scattered
along road to area west of Duck
Creek Pass.

2004: 1200 plants. Hybrids with C.
hookerianum appear common
especially the further one goes from
the pass. Previous population
estimates are vague. 2001: Common
in area. 1992: 1000-5000 individuals,
all in flower. 1983: Some
subpopulations have >100 plants;
another thistle, possibly C.
hookerianum, occurs in all areas,
probably hybridizing.

6320-7600 ft.
Roadsides,
meadows.

A

07

Meagher

Jumping Creek Campground.

Jumping Creek Campground &
access road, about 17.5 miles south
ofNeihartoffU.S.Hwy 89.

2004: Approx. 120 plants. 1992:
Approx. 75 plants, estimate 75% are
C. longistylum.

5850-6240 ft.

Meadows,

roadsides, open

forest.

C

08

Cascade

Neihart. Just north of Neihart,
along FS Road #834 that extends
west up Harley Creek and north to
upland meadows.

2004: Approx 25 C. longistylum plants
among 600-800 plants of C.
hookerianum. 1992: About 1,000
Cirsium plants only 1 % are C.
longistylum. 1990: Frequent in moist
streamside habitats and moist
meadows of upland areas.

5440-7040 ft.
Roadsides,
meadows,

riparian areas.

D

09

Cascade,
Judith Basin

LongBaldy. Long Baldy, Little
Belt Mountains.

Historical record from 1896.

—

H

10

Meagher,
Cascade

O'Brien Creek. Little Belt
Mountains, west of Kings Hill
along FS Road #839 from O'Brien
Park to Lone Tree Park.

2004: Estimate 50-100 C. longistylum
plants mixed in with several thousand
C. hookerianum and hybrids. 1992:
over 3,000 C. hookerianum in Moose
Park, C. longistylum found only along
roads.

7200-7300 ft.

Meadows, open

forest,

roadsides.

C

12

Judith Basin

Hay Coulee. Little Belt
Mountains, south of Sage Creek up
Hay Coulee, about 15 miles west of
Utica.

2004: Estimate 220 C. longistylum
plants within a larger population of C.
hookerianum and hybrids. 1992:
Frequent.

5440-6180 ft.
Meadow.

B

13

Cascade

Belt Creek: Little Belt Mountains,
Belt Creek, along U.S. Hwy 89, 1
mile south of Jefferson Creek,
about 4 miles southeast of Neihart.

2004: Approx. 200 Cirsium plants
observed, about 75 C. longistylum and
the rest C. hookerianum and hybrids.
1992: About 50 plants scattered along
creek & highway for 2 miles either
side of Many Pines Campground.
1986: 170 plants counted, 85 on each
side of the creek; of 41 plants studied,
24 were identified as C. longistylum
and 4 as C. hookerianum; 13
displayed characteristics intermediate
between the two.

6080 ft.

Riparian areas,

roadsides.

C

14

Cascade

Paine Gulch. Little Belt
Mountains, Paine Gulch,
approximately 1.5 - 2.2 miles
upstream from confluence with
Belt Creek.

1987: 11-50 plants observed.

5200-5400 ft.
Disturbed
meadow.

U

15

Cascade

Servoss Mountain. Little Belt
Mountains, southeast side of
Servoss Mountain, north of divide
between Ruby Creek and Henn
Gulch.

A single observation from 1987.

6400 ft.
Motorized trail.

U

16

Meagher

Bair Ranch. From Lake Sutherlin;
about 7 miles NE of White Sulphur
Springs to Bair Reservoir mainly
on the Bair Ranch.

2004: Survey of Bair Ranch and Lake
Sutherlin area estimated 600 C.
longistylum with numerous hybrids,
C. hookerianum, and C. scariosum.
First observation inl986.

5500-5700 ft.
Meadow.

BC

17

Judith Basin

Upper Bear Gulch. Little Belt
Mountains, upper Bear Gulch,
about 20 miles west of Utica.

2004: Approx. 300 C. longistylum
plants mixed in with another 300 C.
hookerianum and hybrids. 1990:
About 100 plants.

6200-6530 ft.

Meadow,
riparian area.

C

E0#

County

Survey Site

Survey Data

Description

Ranking

18

Judith Basin

Skunk Gulch. Little beh
Mountains, Skunk Gulch, about 12
miles northeast of Sapphire
Village.

2004: Approx. 1000 C. longistylum
plants in a larger population
containing C. hookerianum and
hybrids. 1990: Several hundred plants
in flower.

6280-6530 ft.

Meadow,
riparian area.

B

19

Meagher

Thornquist Gulch. Little Beh
Mountains. From White Sulphur
Springs take U.S. Highway 89
north about 15 miles, then FS Road
#831 north about 0.5 mile.
Population extends 0.5-1.0 mile
along Thornquist Gulch and along
Miller Gulch.

2004: Approx. 180 C. longistylum
plants found in a mix of hybrids and
C. hookerianum. 1992: About 50
plants. 1990: About 50 plants.

5680-5840 ft.

Roadsides,
riparian areas,

open forest.

C

20

Judith Basin

Russian Flat. Little Belt
Mountains, Russian Creek, about
18 miles west of Sapphire Village
and along the South Fork Judith
River.

2004: Approx 2000 plants. 1992:
About 600 individuals, approx. 80%
C. longistylum. 1990: Thousands of
plants plus scattered individuals
extending to the east and west about 1
mile.

6350-6640 ft.
Meadow.

A

21

Meagher

Pasture Gulch. Take U.S.
Highway 12 about 5 miles east of
Checkerboard, then go south on FS
Road #694 about 4 miles into
Pasture Gulch.

2004: Approx. 180 plants. 1992: 50
plants. 1991: 50-100 plants scattered
along road and in recently logged
areas.

5300-5640 ft.

Roadsides,

partiaUy logged

slopes.

D

22

Broadwater

Carl Creek. Big Beh Mountains,
along Carl Creek trail, just south of
trailhead off Highway 12.

2004: 12 plants. 1992: 7 plants total.

5440-5480 ft.

Riparian areas,

roadsides.

CD

23

Meagher

Atlanta Creek. Big Beh

Mountains. Atlanta Ridge above
Atlanta Creek, west of Atlanta
Road #575, upper end of ridge and
along Atlanta Creek.

2004: Estimate of 1000 plants with
hybrids and C. hookerianum also
present. 1992: Estimate of 250-F plants
in peak flower, the majority at west

end of meadow.

6400-7440 ft.

Meadows, open

forest, riparian

areas.

A

24

Broadwater

Cement Gulch. Big Beh

Mountains; take County Road 287
up Confederate and Cement
gulches to near Ready Cash Gulch.

2001: 25 to 50 plants.

5600-6100 ft.
Riparian areas.

C

25

Lewis &
Clark

Hogback Mountain. Big Beh

Mountains; fellfield on top of
Hogback Mountain.

Observation from 1992.

7580-7800 ft.
Fellfield.

u

27

Broadwater

Confederate Gulch. Big Beh

Mountains, along Confederate
Gulch just above Cement Gulch.

2004: Estimate of 35 plants. 2001: No
plants located. First observation in
1992.

5220-5300 ft.
Disturbed area.

c

28

Broadwater

Boulder Creek. Big Beh

Mountains, ridgeline above
Boulder Creek, accessible from FS
Road #4171 to logging road to FS
Trail #142, which cuts over the
ridge.

1992: 20-40 plants widely scattered
across exposed slope.

6920-7020 ft.
Meadow.

CD

29

Broadwater

Springs Gulch. Big Beh

Mountains, head of Springs Gulch
on south slopes of Bilk Mountain,
0.3 air mile southwest of the
eastern peak of Bilk Mountain; end
of Springs Gulch Road (FR 1020).

2004: 30 C. longistylum plants in a
mixed population with C.
hookerianum and hybrids. 1992:
About 50 plants; 10% C. longistylum,
20% C. hookerianum and the rest
hybrids.

6640-6840 ft.
Meadow,
roadsides.

CD

30

Broadwater

Long Gulch/Priest Gulch Ridge.

Big Belt Mountains, 2.7 air miles
east of east summit of Bilk
Mountain, ridge at the head of
Long and Priest gulches; and White
Gulch north of Whites City.

2004: About 85 plants in a larger
population containing C. hookerianum
and hybrids. Very weedy. 2001:
Estimated 500 plants, unknown how
many are C. longistylum. Survey
extended the known occurrence
approx. 2 miles along road toward
Needham Mountain. 1992: About 500
individuals observed not all C.
longistylum.

5100-7010 ft.
Meadow.

B?

31

Meagher

Brooks Creek. From junction with
U.S. Highway 12 at Checkerboard,
follow FS Road 581 up Brooks
Creek about 3 miles. Take left fork
about 0.3 mile to site.

2004: About 50 plants, very weedy.
First observed in 1992.

5960-6410 ft.

Meadow, open

forest.

CD

10

Table 1. Continued.

E0#

County

Survey Site

Survey Data

Description

Ranking

32

Meagher

West Fork Flagstaff Creek. From
junction with U.S. Highway 12
about 3 miles southeast of
Checkerboard, follow FS Road
1043 about 3.5 miles to site.

2004: Approx. 250 plants. First
observation in 1992.

5400-5640 ft.
Meadow,

riparian areas,
roadsides,
sagebrush.

BC

33

Meagher

Brooks Creek. From junction with
U.S. Highway 12 at Checkerboard,
follow FS Road 581 up Brooks
Creek about 2 miles. Site is along
road just inside Forest Service
boundary.

2004: No plants found. First
observation in 1992.

5680-5770 ft.

No habitat info

available.

F

34

Meagher

West Fork Checkerboard Creek.

From Checkerboard, follow FS
Road 581 up Brooks Creek about 5
miles. Site is along the south side
of the road beside an unnamed
tributary.

Only observation in 1992.

6350-6440 ft.

No habitat info

available.

U

35

Meagher

West Fork Checkerboard Creek.

Go about 4 miles southeast of
Richardson Creek Campground on
FS Road 211. Site runs along West
Fork Checkerboard Creek to the
southwest and northeast and on
Hall Creek drainage.

2004: Approx. 650 plants. First
observation in 1992.

6250-6530 ft.
Riparian areas.

B

36

Meagher

East Fork Checkerboard Creek.

Follow FS Road 211 about 6 miles
southeast from Richardson Creek
Campground. Site is along the East
Fork Checkerboard Creek to the
north of the road; also along FS
roads 585 and 581.

2004: Estimate of 1,200 plants. First
observation in 1992.

6800-6960 ft.
Meadows,

riparian areas,
roadsides,
sagebrush.

AB

37

Meagher

West Fork Checkerboard Creek.

About 7 miles south of White
Sulphur Springs, take road to east
up Cottonwood Creek. Follow road
to end almost to national forest
boundary. Follow creek north and
take east fork; site begins at fork
and extends about 0.5 mile
upstream.

1992: 3 subpopulations documented
but no population data.

6280-6600 ft.
Meadow.

U

38

Meagher

Newlan Creek. Take FS Road 830
off U.S. Highway 89 just south of
Newlan Creek guard station.
Follow the road about 4 miles up
Newlan Creek. Site is to the north
of road along unnamed tributary;
and along FS Road 830A.

2004: Approx. 400 individuals in a
larger population with C.
hookerianum and hybrids. First
observation in 1992.

5800-6400 ft.

Meadows,
riparian areas.

B

39

Meagher

Sheep Creek. Follow U.S. Hwy
89 northeast from Forest Green
about 2 miles. Take road to right to
quarry about 0.25 mile. Site is
along unnamed tributary of Sheep
Creek.

2004: Approx. 125 plants in a larger
population with C. hookerianum and
hybrids. First observation in 1992.

6200-6440 ft.
Roadsides.

BC

41

Judith Basin

Oka Butte. Take county road that
passes rodeo grounds north of
Judith Gap. Make left turn at
county line, go north about 1.5
miles, then turn west for about 1.7
miles to dirt road. Go about 1 mile,
turn right. Go about 2 miles to site
on either side of road.

A single observation from 1988.

5640-5760 ft.
Roadsides.

U

42

Wheatland

Bartleson Peak. Headwaters of
Hopley Creek, north side of
Bartleson Peak; about 20 air miles
northwest of Harlowton. Approach
possibly via FS Road 8823.

A single observation from 1992.

6500-7500 ft.
Open forest.

U

11

Table 1. Continued.

E0#

County

Survey Site

Survey Data

Description

Ranking

45

Meagher

Grouse Ridge. Big Beh

Mountains, Trout Creek Road to
Dry Gulch Road, east on Beaver
Creek Road (FS 138) through
Indian Flats then east on FS Road
4118.

2001: More than 50 mature plants
with many rosettes over 2 acres.

6610 ft.
Meadow.

c

47

Lewis &
Clark

Indian Flats. Big Belt Mountains.
Trout Creek Road to Dry Gulch
Road, east on Beaver Creek Road
(FS 138) to Indian Flats, Pike
Creek and Jim Ball Basin.

2004: 1 C. longistylum with 12
hybrids and 9 C. hookerianum in Jim
BaU Basin. 34 rosettes present. 2001:
<50 plants with rosettes, covering a
two-mile linear strip of roadside.
Identification uncertain.

6220-6530 ft.
Roadsides.

c

49

Broadwater

Grouse Creek. Big Belt
Mountains, Magpie Gulch Road to
FS Road 425 Gl.

2001: <10 plants, very weedy.

6264 ft.
Roadsides.

D

50

Broadwater

Nary Time Gulch. Big Belt
Mountains, Avalanche Gulch Road
to Nary Time Gulch.

2001: >40 plants, weedy, disturbed
site.

5120-5200 ft.

Roadsides,
riparian areas

C

52

Meagher

Ohio Gulch-Benton Gulch. Big

Belt Mountains, Confederate
Gulch, to Cement Gulch, to Benton
Gulch and some points up Ohio
Gulch.

2001: >75 plants.

5140-5560 ft.

Weedy riparian

area.

C

53

Broadwater

Hellgate Canyon. Big Belt
Mountains, Hellgate Gulch Road,
about 2.5 miles beyond the first
creek crossing.

2001 : 2 plants in area that burned in
2000.

5165 ft.

Weedy riparian

area.

D

54

Meagher

Elk Ridge. Approximately 26.5 air
miles northeast of Helena airport.
Take York Road; at York go to
Nelson, then northeast on Road
138. Turn east at road to Jim Ball
Basin. Follow road to Elk Ridge
(Block Management Unit).

2002: >300 plants in 2
subpopulations.

6690-6990 ft.
Meadow.

BC

56

Meagher

Dry Range. Approximately 20
miles northwest of White Sulphur
Springs on Forest Service & private
lands..

2004: Approx. 2200 C. longistylum
plants with numerous hybrids and a
few C. hookerianum. 2003: Estimated
10,000 plants.

4920-6200 ft.

Meadows, open

forest.

A

57

Judith Basin

Hay Canyon. Little Beh
Mountains. Hay Canyon Road
6390. Site occurs from 0.8 mile to
2 miles up the canyon.

2004: 200 plants. Counted 47
flowering plants of C. longistylum and
putative hybrids that lean towards C.
longistylum. Many rosettes also in the
area. Population is in small meadows
and openings along road.

5410-5610 ft.
Meadows,
roadsides.

BC

58

Judith Basin

Dry Pole Canyon. Little Beh
Mountains. Dry Pole Canyon Road
6392 from bottom of drainage to
end of road.

2004: 100-150 plants. Counted 23
flowering C. longistylum and putative
hybrids that lean towards C.
longistylum. Numerous rosettes also
encountered.

5400-6400 ft.
Meadows.

BC

59

Wheatland

Sawmill Canyon. Little Beh
Mountains. Along Forest Road 584,
Sawmill Canyon.

2004: 8 plants counted. Scattered
flowering plants and rosettes
throughout the drainage. 2 putative
hybrids also observed.

5410-5610 ft.
Riparian areas,

disturbed

meadows, open

forest.

CD

63

Cascade,
Judith Basin

Jefferson Creek-SUde Rock.

Little Beh Mountains.
Approximately 3 miles SE of
Neihart along Jefferson Creek Road
267 and continuing up drainage to
Road 3328 and along Road 251.

2004: Estimate of 200 plants. Mixed
population of C. hookerianum, C.
longistylum and putative hybrids.
Predominantly C. hookerianum in
lower portion of drainage with more
C. longistylum and hybrids higher in
the drainage. Total thistle population
in the area is approx. 1200 plants.

6000-7970 ft.

Roadsides,
riparian areas,

meadows.

C

64

Fergus

Big Snowy Mountains. About 20
miles south of Lewistown.

Specimen coUected in 1960.

—

H

12

Table 1 . Continued.

E0#

County

Survey Site

Survey Data

Description

Ranking

65

Meagher

Coates Pond. Castle Mountains.
From White Sulphur Springs take
Highway 12 east to Checkerboard;
travel southwest on FS Road 581
about 5 miles to FS Road 1043.
Site begins about 2 miles southeast.

2004: Estimate 350 plants; very
weedy.

6270-6290 ft.

Weedy riparian

area, meadow,

sagebrush.

BC

66

Meagher

Fourmile Creek. From White
Sulphur Springs travel east on
Highway 12, turn south of FS Road
211. Population is scattered along
road adjacent to Fourmile Creek to
Richardson Creek Campground.

2004: Counted 114 plants.

5710-5990 ft.

Roadsides,

meadow,

riparian area.

C

67

Meagher

Wagner Gulch. Big Beh

Mountains. From White Sulphur
Springs travel northwest on Road
360 to Wagner Gulch Road 259.
Travel west on Wagner Gulch.

2004: Approx. 100 plants in a larger
population of C. hookerianum and
hybrids.

6380-6580 ft.

Meadows,

roadsides, open

forest.

CD

68

Judith Basin,
Meagher

Elephant Rock. Little Beh
Mountains. From White Sulphur
Springs travel north on FS Road
274 about 9 miles. Population is
along Whitetail Creek.

2004: Estimate of 800-1000 plants, C.
hookerianum and hybrids also present.

6000-6690 ft.
Roadsides,
meadows,

riparian areas.

AB

69

Wheatland

JeUison Place. Little Beh
Mountains. West of Harlowtown
take the county road off Highway
89 for approximately 24 miles to
FS land. Population is along
roadway.

2004: Approx. 125 plants.

5800 ft.
Roadsides,
meadow.

C

70

Meagher

Spring Creek. Little Beh
Mountains. Travel north on FS
Road 274 about 6 miles to FS Road
6393. Travel northeast 3.9 miles to
Basin Creek.

2004: About 200 plants.

5600 ft.

Riparian area,

grassland,

sagebrush.

C

72

Meagher

South Fork Tenderfoot Creek.

Little Belt Mountains. Site is above
junction of Road 6424 and Road
586 to just before the crest where
road drops into the South Fork
Tenderfoot.

2004: Estimate of 30-40 plants, 6 of
them flowering. C. hookerianum and
hybrids also present. Many rosettes
present.

6000-6400 ft.

Roadsides,
riparian areas.

D

E. Habitats

C. longistylum occurs in a variety of open habitats
that receive full to partial sun. The best habitats for
the species occur in montane to subalpine
meadows. Occurrences are also common along
roadsides, herbaceous-dominated riparian areas and
open forests of Douglas-fir, lodgepole pine or
whitebark pine. Plants occur as low 4800 feet
elevation up to approximately 8100 feet with the
majority of the occurrences between approximately
6000 and 7500 feet.

Periodic disturbance appears to play a key role in
the survival and establishment of populations.
Establishment of seedlings in meadow populations
appears to be highest in areas following disturbance
by rodents churning the soil. Fire also appears to

be beneficial to the species with high numbers of
flowering plants and rosettes seen in the Spur Park
and Ant Park areas following fire. Anthropogenic
disturbance also appears to be beneficial under
some circumstances. Roadsides provide habitat for
the species throughout its range due to the bare soil,
lack of competition and the increased availability of
light, water and nutrients that are common along
many mountain roads. These populations are also
susceptible to the negative impacts associated with
roads such as weed invasion, herbicide spraying
and road grading, among other possible threats.

Species composition at local C longistylum sites
varies widely across its range and even within an
individual population. Elevation and the type of
habitat (meadow, open forest, riparian or roadside)
occupied are significant factors in determining

13

species composition. Below is a list of some of the
more common species encountered, organized by
lifeform.

Trees

Pseudotsuga menziesii (Douglas-fir)
Pinus contorta (lodgepole pine)
Pinus albicaulis (whitebark pine)

Shrubs

Artemisia tridentata ssp. vaseyana (mountain big

sage)

Juniperus communis (common juniper)

Juniperus horizontalis (horizontal juniper)

Potentilla fruticosa (shrubby cinquefoil)

Grasses

Wromus inermis (smooth brome)

Festuca idahoensis (Idaho fescue)

Festuca scabrella (rough fescue)

Koeleria macrantha (prairie junegrass)

^Phleum pratense (common timothy)

^Poa pratensis (Kentucky bluegrass)

Stipa richardsonii (Richardson's needlegrass)

Forbs

Achillea millefolium (common yarrow)
Agoseris glauca (false mountain dandelion)
Anemone multifida (cliff anemone)
Antennaria microphylla (rosy pussy-toes)
Arenaria congesta (ballhead sandwort)
Campanula rotundifolia (harebell)
Cerastium arvense (field chickweed)
Galium boreale (northern bedstraw)
Geranium richardsonii (white geranium)
Geranium viscosissimum (sticky geranium)
Geum triflorum (prairie smoke)
Lupinus argenteus (silvery lupine)
Potentilla gracilis (slender cinquefoil)
Solidago multiradiata (mountain goldenrod)
"^Taraxacum officinale (common dandelion)
^Thlaspi arvense (field pennycress)

*non-native species

Figure 5. Cirsium longistylum habitat in the Dry Range.

Figure 6. Cirsium longistylum habitat and flowering
plants near Spur Park after fire.

Known occurrences of C longistylum are
predominantly on calcareous soils derived from
dolomites, limestones or shales. Though intrusions
of coarse-grained metamorphics are common in the
Belts and the Castle Mountains, soils derived from
these parent materials typically do not harbor
populations of long-styled thistle. Unfortunately,
good site-specific soil data are not available for
most of the known populations.

F. Land Ownership

Most occurrences are on National Forest lands
managed by the Helena and Lewis and Clark
National Forests. Ten populations occur partially or
entirely on private lands with the occurrences in the

14

Dry Range and on the Bair Ranch containing two
of the larger populations. The Bair Ranch
population is also the only one that extends onto
state trust lands adjacent to Lake Sutherlin.

G. Potential Threats to Known
Populations

1. Introduced Bio-controls: Rhinocyllus conicus,
an inflorescence-feeding weevil was introduced into
the United States in 1969 for control of Carduus
species, including Carduus nutans (musk thistle).
Pre- and early post-release studies of the weevil on
native Cirsium species demonstrated that the
weevil showed a strong preference for Carduus
species over Cirsium species in terms of
oviposition, feeding and larval growth. Thus an
impact on native Cirsium species was not expected
(Louda and Arnett 2000, Louda 1998). However,
Rhinocyllus conicus is now prevalent on Cirsium
longistylum and many other native thistles including
Cirsium undulatum, C hookerianum, C.
centaureae, C scopulorum and C canescens in
the Rocky Mountain West (Louda and Arnett
2000). Studies by Louda and others (1997) show
reductions in viable seed up to 86% in C.
canescens and an average reduction of 72% in
Cirsium undulatum in Colorado and South Dakota.
Seed reduction in C longistylum during 1991 and
1992 was estimated at 61% and 46% respectively
at one site in the Little Belt Mountains (Heidel
1994). Infestation rates are typically highest on the
terminal or oldest flower heads while later
developing flower heads and seeds may escape
predation. Monitoring of infestation rates by the
U.S. Forest Service at the Kings Hill site in the
Little Belt Mountains produced the following
percentages for 1991-1993 respectively: 80%,
72% and 0% of flowers infested. The elimination
of the weevil at the site in 1993 is believed to be the
result of a late August snow in 1992 that ended the
growing season early and prevented the weevil
from completing its life cycle (Heidel 1994).

Surveys of C longistylum populations in 2004 did
not systematically document infestation rates,
though random sampling of mature flower heads
found the majority of heads infested with weevil

Figure 7. Rhinocyllus conicus weevils on C.
longistylum in the Little Belt Mountains.

larvae. It was also noted that later maturing
flowering heads were typically uninfested due to
inappropriate timing of their development with the
life stages of the weevil. This incomplete
synchrony of the thistles' and weevils' life cycles
has also been documented by Herr (2000) in C
occidentale and by Louda (1998) in C. pitcheri, a
federally threatened species. Additionally, the
results of Herr's seed bank and seed addition
experiments on C occidentale, in conjunction with
an average seed destruction rate of 21% across all
flower heads, indicate that a significant reduction in
seedling establishment is not expected.

Though the weevil appears to have a significant
impact on the total number of viable seeds
produced it is unclear whether this will lead to a
long-term decline of long-styled thistle populations
since a percentage of seeds, particularly from late
maturing heads, escape predation. Field
observations from 1990-2004 have documented
good establishment of rosettes at many sites even
though weevils have been present in the
populations, providing some evidence that enough
seeds escape predation to maintain populations.

2. Hybridization: Hybridization and introgression
of C longistylum with other Cirsium species,
particularly C hookerianum is another potentially
threat to the long-term viability of C longistylum.
Many populations possess individuals with
involucral bract characteristics that are intermediate
between the two species (Schassberger 1991,

15

Poole and Heidel 1993). These intermediate bract
characteristics have been noted in populations
where only a few plants of C. hookerianum are
present. This leads to the possibility that only a few
flowering individuals of C hookerianum may be
enough to contaminate the gene pool of C.
longistylum. However, Brunsfeld and Baldwin's
(1995) genetic analysis provided evidence that C.
longistylum is genetically distinct from its closest
relatives in west-central Montana and that putative
hybrids are genetically similar to "pure" C
longistylum. Their study also showed that C.
longistylum possesses more variability than the
other species sampled but it is unclear whether this
is due to hybridization with the other thistles. Until
wider-ranging and more in-depth genetic studies of
C longistylum and related species are completed it
is unclear what, if any, affect gene flow among
Cirsium species in central Montana may be having
on C longistylum.

3. Recreation: Off-road vehicle use has
historically occurred in areas occupied by the thistle
and was noted in limited areas during recent field
surveys. However, this activity is not believed to
have a significant direct impact on the species'
potential for long-term survival as long as use does
not significantly increase. Indirectly, off -road
vehicles and traffic on designated routes may
impact populations through the spread of weed
seeds and the subsequent establishment of new
weed infestations into C. longistylum habitat.

4. Weed Invasion and Herbicides: As noted
above, weed invasion of C. longistylum habitat and
populations is an increasing threat to the short-term
survival of populations and the long-term survival of
the species. Several non-native plant species are of
particular concern, including Cirsium arvense
(Canada thistle), Bromus inermis (smooth brome)
and Phleum pratense (common timothy). The first
species is a state of Montana designated noxious
weed and, as such, landowners are required to
eradicate or control populations on their land.
Canada thistle is a perennial that reproduces from
wind dispersed seeds and rhizomes and is capable
of rapid expansion and long-distance dispersal. The
habitat requirements of Canada thistle overlap with

that of long-styled thistle and include montane
meadows, riparian areas and roadsides. At present,
populations of Canada thistle occur throughout the
range of long-styled thistle, though it currently is not
having a significant adverse impact.

Bromus inermis and Phleum pratense have long
been used as pasture grasses and for revegetation
projects following fires and other natural and
human-caused disturbances. Both species inhabit
montane to subalpine meadows and roadsides
where they may form dense stands that preclude
the germination and establishment of C.
longistylum. Bromus inermis is of particular
concern in that it is a deep-rooted sod-forming
grass that appears to exclude other species and is
already prevalent in many lower quality C.
longistylum populations. As this species is not a
listed noxious weed in the state it is generally not
controlled and in fact it is still seeded for forage and
revegetation projects. As such, B. inermis
potentially poses the biggest threat to C.
longistylum populations of all wildland weeds.

Many other non-native species have routinely been
documented during surveys for long-styled thistle,
including Carduus nutans, Cirsium vulgar e,
Cynoglossum officinale, Poa pratensis.
Taraxacum officinale (common dandelion) and
Thlaspi arvense (field pennycress). Further
monitoring of C longistylum populations is
required to determine the impact that invasive
weeds are having on individual populations and on
the long-term viability of the species. Due to the
network of roads that occur throughout the range
and habitat of C longistylum, expansion of non-
native species should be expected in the future and
weed control and eradication measures should be
implemented as appropriate.

Herbicide spraying directly on C longistylum
plants has been noted during past surveys,
particularly along roadsides. This detrimental
activity, though limited in scope, is easily
preventable by increasing awareness of the species
and the distinction between native and exotic
thistles.

16

5. Grazing: Grazing is a historical and current use
in many areas occupied by long-styled thistle.
Consumption of flowering stalks and rosettes by
cattle has been observed (Figures 8-9) in the field,
though this is usually minimal as long as more
palatable vegetation is present. Livestock may
have an indirect adverse impact by spreading
weeds into previously uninfested areas. However,

livestock grazing may reduce competition and
increase bare soil, leading to an increase in
germination and establishment of C longistylum in
some sites. Currently, light to moderate grazing is
not believed to have direct significant adverse
impacts on the long-term survival of the species,
though short-term adverse impacts may occur in
localized areas.

^^ys^;^ .. -J

*^^A

gUi

i^

Figures 8-9. Grazing impacts on Cirsium longistylum.

17

III. Assessment and

Recommendations

A. General Assessment of Trends and
Status

As of 2004, 47 extant occurrences of Cirsium
longistylum are known across the species' range.
Of these, seven are ranked as having "excellent" or
"good to excellent" long-term viability, another five
have "good" viability and an additional seven have
"good to fair" estimated viability. The seven
highest quality populations, totahng approximately
18,000 plants, represent the majority of the
documented/estimated plants in 2004. However,
the majority of occurrences occupy roadsides, have
low population numbers and/or inhabit degraded
habitats that result in fair to poor long-term
estimated viability for those populations.

Both long-term and short-term trends for the
species are not readily apparent. Surveys previous
to 2004 did not thoroughly document the extent of
many populations and/or population estimates were
vague, imprecise or even non-existent. However,
data from several populations suggest that
populations have remained relatively stable over
two decades with large yearly fluctuations possible.
Germination and establishment of new plants
appears to be partially dependent on several
factors, including climate patterns and periodic
disturbance from fire, rodent activity, grazing or
other sources that result in a favorable seedbed.
Flowering of plants appears to be partially related to
availability of adequate moisture and nutrients.
Disturbances such as fire that increase both of
these factors may lead to increased flowering the
following year or two, as was seen in the Ant Park
and Spur Park areas in the Little Belts. Large
variations in rosette numbers and flowering plants is
possible over a time period of several years,
meaning that many years of population data are
needed to accurately estimate trends.

Demographic monitoring plots (Figures 10-12)
established in 1990 by the Montana Natural
Heritage Program provide limited data on
population trends at three sites. Since these plots
were not established for the purpose of population
monitoring, their limited number and size do not
provide a good overall picture. All three sites show
flowering plants in 2004 within the range of
variation measured in the early 1990's. Rosettes
have declined in 2004 relative to counts in the
1990' s at the Kings Hill and Neihart sites. In
contrast, the Russian Creek site shows a slight
population increase in 2004 over past counts.

King Hill #1 Site

Figure 10. Permanent monitoring plot (15' radius) near
Kings Hill, Little Belt Mountains. No data is available for
rosettes in 1993.

Russian Creek

Figure 1 1 . Permanent monitoring plot (37' radius) near
Russian Creek, Little Belt Mountains. No data is
available for rosettes in 1993.

18

Neihart
{Cirsium hookerianum)

Figure 12. Permanent monitoring plot (15' radius) near
Neihart, Little Belt Mountains. No data is available for
rosettes in 1993. This plot is actually occupied by C.
hookerianum, not C. longistylum.

A final semi-quantitative assessment was
conducted using the approaches outlined by Regan,
Master and Hammerson (2004) and adapted by the
Montana Natural Heritage Program for use in
ranking Animal Species of Concern (MTNHP
2004). Both of these similar assessment methods
assign points to factors such as number of
occurrences, population size, area or range extent,
trends and threats. Some factors may not be used
if data is missing or an estimate of the parameter is
too uncertain. The points from the most pertinent
criteria are added together to form a final score for
the species. Lastly, a heritage rank of 1 to 5 at a
global and/or state level is assigned based on the
final score. The ranking criteria and scores
assigned to C. longistylum are found in Table 2
using the two slightly different scoring methods.

Table 2. Ranking factors and assigned scores for the C. longistylum assessment. The first numbers in the Point
Allocation column are those used in the scoring method of Regan, Master and Hammerson (2004) and the second
numbers in the column are those used in the method outlined by the MTNHP State rank criteria for Animal Species
of Concern. See Regan, Master and Hammerson (2004) and MTNHP (2004) for a complete discussion of the
methodologies.

Factor

Parameter Estimate

Category

Point Allocation

# of Occurrences

21-80

C

3/Not used

Condition of
Occurrences

Some (13-40) with good
or excellent viability

D

0/Not used

Population Size

10,000-100,000 plants

F

0/0

Area of
Occupancy

20-100 km2 (5,000-
25,000 acres)

D

Not used/0.25

Geographic
Range

1,000-5,000 km2 (400-
2,000 sq. miles)

D

Not used/Not used

Long-term Trend

Relatively stable {+- 25%
change)

E

Short-term Trend

Short-term trend
unknown

U

Not used/Not used

Threats-Severity

Low to moderate

C-D

-0.38/-0.38

Threats-Scope

Moderate?

Threats-
Immediacy

Moderate to high

Intrinsic
Vulnerability

Not intrinsically

vulnerable to moderately

vulnerable

B-C

Not used/Not used

Environmental
Specificity

Narrow speciahst with

key requirements

common

B

Not used/Not used

Initial Point
Allocation

0/3.5

Score

2.62/2.87

Rank

G3-S3/G3-S3

19

The assignment of the threat attributes of severity,
scope and immediacy is still a mostly subjective
process and as such is open to interpretation and
discussion. The two most apparent threats to the
viability of the species appear to be from
competition and loss of habitat due to weed invasion
and from seed predation by the Rhinocyllus
weevil. In terms of weed invasion, roadside sites
and lower elevation populations are currently most
affected by weeds. Higher elevation sites typically
have very few weeds that are currently posing
problems and/or are not immediately threatened by
invasion of weeds that are likely to cause major
problems in these colder environments. This may
change if new weeds that possess the ability to
rapidly reproduce and spread become established in
these montane and subalpine meadows.

B. Status Recommendation

Population estimates of approximately 30,000
plants, including seven high quality populations,
scattered over four mountain ranges are promising
for the long-term viability of the species. Habitat in
the largest populations is generally of high quality
with few if any problem weeds posing significant
and immediate threats. In the near future, little
change in habitat quality is expected in these
populations. Sites are mostly on National Forest
lands that provide a degree of protection and two
large populations on private lands that have a
history of light to moderate grazing appear stable.
Also of benefit at this time is the active weed
control program employed by the private
landowners on their lands.

The introduced bio-control weevil has already
invaded most, if not all, of the populations of C.
longistylum. However, weevil population levels at
the higher elevation sites are probably cyclical in
central Montana due to variations in yearly
weather. Cold weather and associated snowfalls
early or late in the growing season appear to have a
significant affect on the weevils' ability to survive
and reproduce, resulting in significant declines or
local eradication of the weevil for short time spans.
When coupled with the lack of data on the
influence that seed predation from the weevil is
having on long-styled thistle populations, it becomes
difficult to assign an accurate threat ranking,
particularly in terms of severity.

Long- and short-term population trends are difficult
to gauge due to the lack of good survey data over
many years. However, available data and
observations provide some evidence that population
levels have at least remained fairly stable over the
past decade, with significant yearly fluctuations
possible. Threats posed by invasive weeds and the
introduced bio-control agent do provide reason for
concern. Thus, population monitoring of long-styled
thistle should continue in the future.

As a result of this assessment, the Montana Natural
Heritage Program ranking of the species will
change from the current G2/S2 to a G3/S3 (see
Appendix A: Global/State Rank Definitions).

20

Literature Cit e d

Brunsfeld, SJ. and C.T. Baldwin. 1994.
Preliminary genetic analysis of Cirsium
longistylum (long-styled thistle), a candidate
threatened species. Unpublished report to the U.S.
Fish and Wildlife Service. Wildland Plant
Ecogenetics Cooperative, University of Idaho in
cooperation with the Montana Natural Heritage
Program, Helena, MT. 20 pp.

Dorn, R. 1984. Vascular plants of Montana.
Mountain West Publishing. Cheyanne, WY. 276
pp.

Gardner, R.C. 1974. Systematics of Cirsium
(Compositae) in Wyoming. Madrono 22:239-265.

Mathews, S. 1990. Cirsium longistylum project:
summary report (chromosome counts). Montana
State University, Bozeman for the Montana Natural
Heritage Program. 3 pp.

Mincemoyer S.A. 2004. Plant species of concern
survey form. On file at the Montana Natural
Heritage Program. Helena, MT.

Montana Natural Heritage Program. 2004. State
rank criteria for animal species of concern, on-line
(http://nhp.nris.state.mt.us/animal/index.html).

Moore, R. J. and C. Frankton. 1974. The thistles
of Canada. Research Branch Canada Department
of Agriculture. Monograph No. 10. Ottawa,
Canada. 1 1 1 pp.

Heidel, B. 1994. Monitoring study of Cirsium
longistylum (long-styled thistle), a candidate
threatened species. Montana Natural Heritage
Program. Helena, MT. 32 pp.

Moore, R. J. and C. Frankton. 1963.
Cytotaxonomic notes on some Cirsium species of
the western United States. Canadian Journal of
Botany 441: 1553-1567.

Holmgren P.K. and N.H. Holmgren. 1990. Index
Herbariorum, Edition 8: Part I. The Herbaria of the
World. New York Botanical Garden Press. 704
pp. on-line (http://207. 156.243. 8/emu/ih/index.php).

Louda, S.M. 1998. Population growth of
Rhinocyllus conicus (Coleoptera: Curculionidae)
on two species of native thistles in prairie.
Environmental Entomology 27(4): 834-841.

Louda, S.M. and A.E.Amett. 2000. Predicting
non-target ecological effects of biological control
agents: evidence from Rhinocyllus conicus.
Proceedings of the X International Symposium on
Biological Control of Weeds. 4-14 July 1999.
Montana State University, Bozeman, MT. pp 551-
567.

Louda, S.M., D. Kendall, J. Connor and D.
Simberloff. 1997. Ecological effects of an insect
introduced for the biological control of weeds.
Science 277:1088-1090.

Olsen, L. 2003. Sensitive plant surveys in the Dry
Range, Helena National Forest. Unpublished report
on file at the Helena National Forest. Helena, MT.

Ownbey, G.B. and Y. Hsi. 1963. Chromosome
numbers in some North American species of the
genus Cirsium. Rhodora 65:339-354.

Poole, J.M. and B.L. Heidel. 1993. Sensitive plant
surveys in the Big Belts and Elkhom Mtns., Helena
National Forest. Montana Natural Heritage
Program. Helena, MT. 129 pp.

Regan, T.J., L.L. Master and G.A. Hammerson.
2004. Capturing expert knowledge for threatened
species assessments: a case study using
NatureServe conservation status ranks. Acta
Oecologica 26:95-107.

Schassberger, L.A. 1991. Report on the
conservation status of Cirsium longistylum, a
candidate threatened species. Montana Natural
Heritage Program. Helena, MT. 92 pp.

21

USDANRCS. 2004. The PLANTS Database,
Version 3.5 (http://plants.usda.gov). National Plant
Data Center, Baton Rouge, LA 70874-4490 USA.

U.S. Department of Interior. 1990. Endangered
and threatened wildlife and plants; review of plant
taxa for listing as endangered or threatened species;
notice of review. Federal Register 50 CFR Part 17:
6184-6299.

22

AppendixA. Global/State Rank Definitions

Heritage Pro GRAM Ranks

The international network of Natural Heritage Programs employs a standardized ranking system to denote
global (range-wide) and state status. Species are assigned numeric ranks ranging from 1 to 5, reflecting
the relative degree to which they are "at-risk". Rank definitions are given below. A number of factors are
considered in assigning ranks — the number, size and distribution of known "occurrences" or populations,
population trends (if known), habitat sensitivity, and threat. Factors in a species' life history that make it
especially vulnerable are also considered (e.g., dependence on a specific pollinator).

Global Rank Definitions (NatureServe2003)

Gl Critically imperiled because of extreme rarity and/or other factors making it highly

vulnerable to extinction
G2 Imperiled because of rarity and/or other factors making it vulnerable to extinction

G3 Vulnerable because of rarity or restricted range and/or other factors, even though it may

be abundant at some of its locations
G4 Apparently secure, though it may be quite rare in parts of its range, especially at the

periphery
G5 Demonstrably secure, though it may be quite rare in parts of its range, especially at the

periphery
Tl-5 Infraspecific Taxon (trinomial) — The status of infraspecific taxa (subspecies or

varieties) are indicated by a "T-rank" following the species' global rank

State Rank Definitions

51 At high risk because of extremely limited and potentially declining numbers,
extent and/or habitat, making it highly vulnerable to extirpation in the state

52 At risk because of very limited and potentially declining numbers, extent and/or
habitat, making it vulnerable to extirpation in the state

53 Potentially at risk because of limited and potentially declining numbers, extent
and/or habitat, even though it may be abundant in some areas

54 Uncommon but not rare (although it may be rare in parts of its range), and usually
widespread. Apparently not vulnerable in most of its range, but possibly cause for
long-term concern

55 Common, widespread, and abundant (although it may be rare in parts of its
range). Not vulnerable in most of its range

Combination Ra n k s

G#G# or S#S# Range Rank — A numeric range rank (e.g., G2G3) used to indicate uncertainty about
the exact status of a taxon

Qualifiers

NR Not ranked

Q Questionable taxonomy that may reduce conservation priority — Distinctiveness of

this entity as a taxon at the current level is questionable; resolution of this uncertainty may
result in change from a species to a subspecies or hybrid, or inclusion of this taxon in
another taxon, with the resulting taxon having a lower-priority (numerically higher)
conservation status rank

Appendix A - 1

X Presumed Extinct — Species believed to be extinct throughout its range. Not located

despite intensive searches of historical sites and other appropriate habitat, and virtually no
likelihood that it will be rediscovered

H Possibly Extinct — Species known from only historical occurrences, but may never-the-

less still be extant; further searching needed

U Unrankable — Species currently unrankable due to lack of information or due to substan-

tially conflicting information about status or trends

HYB Hybrid — Entity not ranked because it represents an interspecific hybrid and not a species

? Inexact Numeric Rank — Denotes inexact numeric rank

C Captive or Cultivated Only — Species at present is extant only in captivity or cultivation,

or as a reintroduced population not yet established

A Accidental — Species is accidental or casual in Montana, in other words, infrequent and

outside usual range. Includes species (usually birds or butterflies) recorded once or only a
few times at a location. A few of these species may have bred on the one or two occa-
sions they were recorded

Z Zero Occurrences — Species is present but lacking practical conservation concern in

Montana because there are no definable occurrences, although the taxon is native and
appears regularly in Montana

P Potential — Potential that species occurs in Montana but no extant or historic occurrences

are accepted

R Reported — Species reported in Montana but without a basis for either accepting or

rejecting the report, or the report not yet reviewed locally. Some of these are very recent
discoveries for which the program has not yet received first-hand information; others are
old, obscure reports

SYN Synonym — Species reported as occurring in Montana, but the Montana Natural Heritage

Program does not recognize the taxon; therefore the species is not assigned a rank

* A rank has been assigned and is under review. Contact the Montana Natural Heritage

Program for assigned rank

B Breeding — Rank refers to the breeding population of the species in Montana

N Nonbreeding — Rank refers to the non-breeding population of the species in Montana

Appendix A - 2

AppendixB. Element Occurrence Rank Definitions

Element Occurrence Rank Definitions

A - Excellent estimated viability/ecological integrity

A? - Possibly excellent estimated viability/ecological integrity

AB - Excellent or good estimated viability/ecological integrity

AC - Excellent, good, or fair estimated viability/ecological integrity

B - Good estimated viability/ecological integrity

B? - Possibly good estimated viability/ecological integrity

BC - Good or fair estimated viability/ecological integrity

BD - Good, fair, or poor estimated viability/ecological integrity

C - Fair estimated viability/ecological integrity

C? - Possibly fair estimated viability/ecological integrity

CD - Fair or poor estimated viability/ecological integrity

D - Poor estimated viability/ecological integrity

D? - Possibly poor estimated viability/ecological integrity

E - Verified extant (viability/ecological integrity not assessed)

F - Failed to find

F? - Possibly failed to find

H - Historical

H? - Possibly historical

X - Extirpated

X? - Possibly extirpated

U - Unrankable

NR - Not ranked

Appendix B - 1

Appendix C. Element Occurrence Maps forCirsium

LONGISTYLUM

Figure 1. Extant Occurrences of Cirsium longistylum in the northern Big Belts C-2

Figure 2. Extant Occurrences of Cirsium longistylum in the central and southern Big Belts

and the western Castle Mountains C-3

Figure 3. Extant Occurrences of Cirsium longistylum in the Dry Range and the western

Little Belt Mountains C-4

Figure 4. Extant Occurrences of Cirsium longistylum in the northern Little Belts C-5

Figure 5. Extant Occurrences of Cirsium longistylum in the central and southern Little Belts C-6

Figure 6. Extant Occurrences of Cirsium longistylum in the Castle Mountains and Bair

Ranch areas C-7

Figure 7. Extant Occurrences of Cirsium longistylum in the eastern Little Belts C-8

Appendix C - 1

Figure 1. Extant Occurrences of Cirsium longistylum in the northern Big Belts.

Figure 2. Extant Occurrences of Cirsium longistylum in the central and southern Big Belts and the western Castle Mountains.

30^ 24 ^r tr =^j

X'

n

Figure 3. Extant Occurrences of Cirsium longistylum in the Dry Range and the western Little Belt Mountains.

Figure 4. Extant Occurrences of Cirsium longistylum in the northern Little Belts.

Appendix C - 5

Figure 5. Extant Occurrences of Cirsium longistylum in the central and southern Little Belts.

On

Figure 6. Extant Occurrences of Cirsium longistylum in the Castle Mountains and Bair Ranch areas.

n

Legend

)— piT- Streams
Highways

Roads

Cirsium longistylum

2 T 4 Miles

J p I

Figure 7. Extant Occurrences of Cirsium longistylum in the eastern Little Belts.

Oo