Cirsium pitcheri
(Torr. ex Eat.) Torr. & Gray
Dune Thistle
G3VulnerableGlobal Rank
HighThreat Impact
U.S. Fish & Wildlife Service, https://www.usa.gov/government-works
Identity
Unique IDELEMENT_GLOBAL.2.130152
Element CodePDAST2E2A0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderAsterales
FamilyAsteraceae
GenusCirsium
Other Common Names
Chardon de Pitcher (FR) Pitcher's Thistle (EN) sand dune thistle (EN) Sand-dune Thistle (EN)
Concept Reference
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2020-03-23
Change Date2020-03-23
Edition Date2020-03-23
Edition AuthorsLosey, J.; rev. by W.R. Ostlie (MRO) and S. Gottlieb (1990), rev. Maybury/Penskar (1996), K. Doyle (2014), rev. Treher (2020)
Threat ImpactHigh
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of Occurrences81 - 300
Rank Reasons
Cirsium pitcheri is one of the few Great Lakes Region endemics, occurring in Canada and the United States. This plant is found in a narrow band along the margins of Lakes Michigan, Huron, and Superior. Most extant sites (over 150) are in Michigan; several remain in Wisconsin, Indiana, and Ontario; none remain in Illinois. There are many robust populations. The recent discovery of three escaped biocontrol species and the threat these species pose on C. pitcheri survival and fecundity has been slow to impact the species rangewide. Other factors such as development and associated manipulation of shoreline habitat, recreation, inbreeding, predation by goldfinches, competition with invasive species, and climate change continue to threaten C. pitcheri occurrences. Because this species has a limited ability to disperse seeds widely, large colonies may be necessary to effectively colonize or recolonize naturally disturbed sites within its dynamic dune ecosystem.
Range Extent Comments
Cirsium pitcheri is a Great Lakes endemic, found along the sandy shores of Lakes Michigan, Huron and Superior in Michigan, Illinois , Indiana, Wisconsin, and Ontario.
Occurrences Comments
Rangewide, there are over 200 presumably extant occurrences. There are 170 occurrences in Michigan including those historic and extirpated. There are 8 extant sites in Wisconsin, 16 in Indiana, and 28 extant sites in Ontario, Canada. This species was extirpated from Illinois but successfully reintroduced to three occurrences.
Threat Impact Comments
Cirsium pitcheri is apparently able to withstand occasional, but not frequent, disturbances (USFWS 1987). Habitat destruction through ATV use, human trampling (WI NHP 1990, Dobberpuhl and Gibson 1987) and other recreational activities (McEachern et al. 1989) appears to be a major threat to populations of the species. However, some of these activities may actually encourage habitat for seed germination (Slaughter and Cuthrell 2017).
Fragmentation of, and habitat destruction within dune fields through road and retaining wall construction, sand mining (Nepstad 1981, Randall 1978) and lakeshore development (USFWS 1987, Keddy and Keddy 1984, Alverson 1981) prevents dispersal and reduces gene flow between existing populations (McEachern et al. 1989). Similar actions result in the alteration of local geomorphic processes necessary for dune formation and habitat maintenance.
Artificial dune stabilization through the action of exotic plant species (sweet clover, thistles, etc.) and land management agencies (plantings of white cedar, Ammophila breviligulata, etc.) has served to reduce in size and eliminate available habitat in many areas (McEachern et al. 1989, Dobberpuhl and Gibson 1987). Construction of off-shore structures such as jetties and on-shore fences can alter the dynamic dune processes essential for long-term habitation by C. pitcheri (Pavlovic pers. comm.).
Non-native species compete with C. pitcheri for habitat and resources. Rand et al. (2015) found that Centaurea stoebe negatively impacted the establishment, survival, and flowering of this species.
Fluctuating lake levels pose an immediate threat to populations that become established in areas subject to potential flooding. Dobberpuhl and Gibson (1987) reported that a population of 48 plants in Wisconsin had apparently been submerged by unusually high lake levels. These same high water levels pose an additional threat through excessive beach erosion (White 1981). Two severe storms caused major damage to populations at the Pukaskwa National Park in Ontario in 1986 (Mosquin et al. 1986). Flood waters from a raging creek and high waves off Lake Superior destroyed major portions of two populations. In the long term, however, it is these fluctuating lake levels that create the habitat necessary for the long-term survival of the species. Populations should not be artificially guarded by fences, walls or other structures that would impede on this dynamic process.
Keddy (1988) stated that fire was a threat to C. pitcheri populations. In a fire at an Indiana site, seedlings died but rosettes and flowering plants survived. Those plants that survived responded by producing numerous shoots. It is likely that C. pitcheri, by evolving with frequent fires on the sand dunes along the Great Lakes, responds favorably to such events. In fact, these fires may be significant in the maintenance of open, unforested dune habitats. Gradual degradation of habitat through woody plant succession is an additional threat (White 1981).
Some landowners have eradicated the plant in the belief that it is a noxious weed (USFWS 1987, Alverson 1981). Continued action of this sort could mark the demise of populations on private lands.
Introgressive hybridization with non-native thistles (e.g.., C. vulgare) may be a concern for this species. Dobberpuhl and Gibson (1987) stated that a purple color form at a Wisconsin site should be studied to determine its origin. This color has also been noted in Ontario populations (Keddy 1981).
Keddy and Keddy (1984) estimated that the presence of the plume moth larvae in C. pitcheri has resulted in an estimated 14%-40% reduction in seed potential (depending on habitat) in populations from Ontario. Mosquin et al. (1986), however, suggested that the plume moth and C. pitcheri may be mutually beneficial and may actually increase flower and consequently, seed production due to the numerous branches produced by injured plants. In order to determine the seriousness of this potential threat, additional research to determine to what extent seed set is hindered or enhanced by the moth is needed. This moth has been observed in Wisconsin (Dobberpuhl and Gibson 1987) and Michigan (Loveless 1983) as well.
Parasitism in the form of a fungus has occurred on a number of plants in a moist, mossy area at the base of a dune blowout in Wisconsin (Dobberpuhl and Gibson 1987). It is not known to what extent this fungus threatens the species.
Herbivory on plants has been noted in the form of an unidentified hymenopteran larvae and a small mammal (Keddy and Keddy 1984). Nepstad (1981) stated that several juvenile plants had been destroyed by rabbits. Deer browse within Sleeping Bear Dunes National Lakeshore has been shown to pose little threat to thistle populations (Hazlett and van de Kopple 1983).
Larinus planus, a seed-predating weevil adventive to North America, has spread around the US as biocontrol on non-native thistles (Havens et al. 2012). This species has been found on Cirsium pitcheri plants at multiple sites in Wisconsin, Indiana and Michigan and has been shown to reduce seed output by approximately 50% (Havens et al 2012; Pavlovic, pers. comm.). Rhinocyllus conicus and Cleonus piger, two more escaped biocontrol pests, have also been found on Cirsium pitcheri plants in Indiana (Pavlovic, pers. comm.). The impacts of these two invertebrates are largely unknown, but preliminary results suggest they each have a negative affect on plant fecundity and/or survival (Havens et al 2012; Pavlovic, pers. comm.).
Fragmentation of, and habitat destruction within dune fields through road and retaining wall construction, sand mining (Nepstad 1981, Randall 1978) and lakeshore development (USFWS 1987, Keddy and Keddy 1984, Alverson 1981) prevents dispersal and reduces gene flow between existing populations (McEachern et al. 1989). Similar actions result in the alteration of local geomorphic processes necessary for dune formation and habitat maintenance.
Artificial dune stabilization through the action of exotic plant species (sweet clover, thistles, etc.) and land management agencies (plantings of white cedar, Ammophila breviligulata, etc.) has served to reduce in size and eliminate available habitat in many areas (McEachern et al. 1989, Dobberpuhl and Gibson 1987). Construction of off-shore structures such as jetties and on-shore fences can alter the dynamic dune processes essential for long-term habitation by C. pitcheri (Pavlovic pers. comm.).
Non-native species compete with C. pitcheri for habitat and resources. Rand et al. (2015) found that Centaurea stoebe negatively impacted the establishment, survival, and flowering of this species.
Fluctuating lake levels pose an immediate threat to populations that become established in areas subject to potential flooding. Dobberpuhl and Gibson (1987) reported that a population of 48 plants in Wisconsin had apparently been submerged by unusually high lake levels. These same high water levels pose an additional threat through excessive beach erosion (White 1981). Two severe storms caused major damage to populations at the Pukaskwa National Park in Ontario in 1986 (Mosquin et al. 1986). Flood waters from a raging creek and high waves off Lake Superior destroyed major portions of two populations. In the long term, however, it is these fluctuating lake levels that create the habitat necessary for the long-term survival of the species. Populations should not be artificially guarded by fences, walls or other structures that would impede on this dynamic process.
Keddy (1988) stated that fire was a threat to C. pitcheri populations. In a fire at an Indiana site, seedlings died but rosettes and flowering plants survived. Those plants that survived responded by producing numerous shoots. It is likely that C. pitcheri, by evolving with frequent fires on the sand dunes along the Great Lakes, responds favorably to such events. In fact, these fires may be significant in the maintenance of open, unforested dune habitats. Gradual degradation of habitat through woody plant succession is an additional threat (White 1981).
Some landowners have eradicated the plant in the belief that it is a noxious weed (USFWS 1987, Alverson 1981). Continued action of this sort could mark the demise of populations on private lands.
Introgressive hybridization with non-native thistles (e.g.., C. vulgare) may be a concern for this species. Dobberpuhl and Gibson (1987) stated that a purple color form at a Wisconsin site should be studied to determine its origin. This color has also been noted in Ontario populations (Keddy 1981).
Keddy and Keddy (1984) estimated that the presence of the plume moth larvae in C. pitcheri has resulted in an estimated 14%-40% reduction in seed potential (depending on habitat) in populations from Ontario. Mosquin et al. (1986), however, suggested that the plume moth and C. pitcheri may be mutually beneficial and may actually increase flower and consequently, seed production due to the numerous branches produced by injured plants. In order to determine the seriousness of this potential threat, additional research to determine to what extent seed set is hindered or enhanced by the moth is needed. This moth has been observed in Wisconsin (Dobberpuhl and Gibson 1987) and Michigan (Loveless 1983) as well.
Parasitism in the form of a fungus has occurred on a number of plants in a moist, mossy area at the base of a dune blowout in Wisconsin (Dobberpuhl and Gibson 1987). It is not known to what extent this fungus threatens the species.
Herbivory on plants has been noted in the form of an unidentified hymenopteran larvae and a small mammal (Keddy and Keddy 1984). Nepstad (1981) stated that several juvenile plants had been destroyed by rabbits. Deer browse within Sleeping Bear Dunes National Lakeshore has been shown to pose little threat to thistle populations (Hazlett and van de Kopple 1983).
Larinus planus, a seed-predating weevil adventive to North America, has spread around the US as biocontrol on non-native thistles (Havens et al. 2012). This species has been found on Cirsium pitcheri plants at multiple sites in Wisconsin, Indiana and Michigan and has been shown to reduce seed output by approximately 50% (Havens et al 2012; Pavlovic, pers. comm.). Rhinocyllus conicus and Cleonus piger, two more escaped biocontrol pests, have also been found on Cirsium pitcheri plants in Indiana (Pavlovic, pers. comm.). The impacts of these two invertebrates are largely unknown, but preliminary results suggest they each have a negative affect on plant fecundity and/or survival (Havens et al 2012; Pavlovic, pers. comm.).
Ecology & Habitat
Habitat
Cirsium pitcheri occurs most prominently in Michigan, occurring in 18 counties along the shorelines of Lakes Michigan, Huron and Superior (Nepstad 1981). In Wisconsin, the species currently exists in eight sites in four counties on the Lake Superior shoreline (Alverson 1981). The species occurs at seven extant sites along Lake Michigan in Indiana (IN NHP 1989), but has been extirpated from Illinois (Sidle 1987, White 1981). It is also known from roughly 12 extant sites in Ontario, including a population on the shoreline of Lake Superior (Keddy and Keddy 1984, Keddy 1988).
Pitcher's thistle is a regional endemic restricted to the dune habitats in the western Great Lakes region (USFWS 1987, Dobberpuhl and Gibson 1987, Keddy and Keddy 1984, Loveless 1983, Guire and Voss 1963). The species is a colonizer on open dune ridges, dune blowouts, and along disturbed sites in sand dunes, but is found on stabilized grassy sand terraces, sandy gravel flats and dune valleys as well (Loveless 1983). In all habitat types, however, the species appears to establish itself only in very open, sandy soil (Loveless 1983).
McEachern et al. (1989) described the habitats associated with the lakeshores as: 1) extremely exposed open communities on lake level foredunes and dune bluff edges dominated by Ammophila breviligulata, 2) transitional communities dominated by three dune grasses, A. breviligulata, Calamovilfa longifolia and Schizachyrium scoparium, and 3) stabilized inland blowouts characterized by S. scoparium/C. longifolia codominance and moderate vegetation and litter accumulation. These three habitat types mark a successional gradient, in which A. breviligulata, adapted to high rates of sand deposition occurring in the shoreline habitats, is replaced by the more competitive C. longifolia and finally, S. scoparium in progressively stable inland areas (McEachern et al. 1989). Associated with this change in dominant vegetation along a shoreline to inland transect, there is an equally significant reduction in the percentage of bare ground. This amount of bare ground is apparently significant, for it is in the most stable, S. scoparium dominated areas that C. pitcheri is the least abundant (McEachern et al. 1989).
In Michigan, C. pitcheri is most common along the northern and northeastern shore of Lake Michigan, although small populations are known from the southeastern shores of Lake Michigan and northern Lake Huron (Crispin and Penskar 1990). A few populations also occur along Lake Superior. Cirsium pitcheri typically grows in association with Ammophila breviligulata, Schizachyrium scoparium, Arabis lyrata, Arctostaphylos uva-ursi, Calamovilfa longifolia and Agropyron dasystachyum (Crispin and Penskar 1990, MI NFI 1990). At disturbed sites, Asclepias syriaca may be present (Crispin and Penskar 1990).
At Sleeping Bear Dunes National Lakeshore in Michigan, the species is apparently doing well, even in the intensely utilized areas around the marina (Hazlett and van de Kopple 1983). A recent survey by McEachern et al. (1989) found that C. pitcheri was occupying much of its potential habitat: foredunes, blowouts, dune ridges, valleys and slopes. Although C. pitcheri was least common from the backslopes of inland dunes, localized populations were found there as well.
On the Manitou Islands portion of Sleeping Bear Lakeshore, plants have been found on perched (260 feet above Lake Michigan, on glacial moraines) and coastal dunes. McEachern et al. (1989) found that plants growing on the dunes of South Manitou Island appeared more stunted and were more dispersed than those on the mainland, possibly reflecting the harsher environment of the island. Associates on a gravel lag behind a coastal dune complex at Dimmick's Point on North Manitou Island include Agropyron dasystachyum, Schizachyrium scoparium, Anemone multifida, Artemisia caudata, Betula papyrifera, Campanula rotundifolia, Carex garberi, Thuja occidentalis and Zygadenus glaucus with an overstory of Betula papyrifera. Associates in a dune blowout on South Manitou include Schizachyrium scoparium, Anemone multifida, Arctostaphylos uva-ursi, Arenaria stricta, Aster sp., Calamovilfa longifolia, Coreopsis palmata, Equisetum hyemale, Ostrya virginiana, Polygonatum pubescens, Prunus virginiana, Trientalis borealis, Trillium grandiflorum, Viburnum acerifolium, Viola canadensis and Viola sp. (Hazlett and van de Kopple 1983). For additional habitat information pertinent to Sleeping Bear National Lakeshore, see McEachern et al. (1989), Hazlett (1986) and Loveless (1983).
At Grand Sable Dunes within the Pictured Rocks National Lakeshore of Michigan, McEachern et al. (1989) found the populations occupying dune and blowout habitats ranging from the dune bluff inland to wooded areas. In contrast to Sleeping Bear, populations were scattered and were far less abundant. For habitat information concerning populations at Pictured Rocks National Lakeshore, see McEachern et al. (1989).
Within the state of Indiana, plants have been observed on dunes, foredunes, blowouts and beaches along Lake Michigan (IN NHP 1989). At the Indiana Dunes National Lakeshore, Bowles et al. (1985) found Cirsium pitcheri restricted to early and mid-successional blowouts on the high dunes adjacent to Lake Michigan. It appeared to be absent from the first foredune. Sites were extremely well-drained and support sparse dry sand prairie-like communities (Bowles et al. 1985). A recent survey of the site by McEachern et al. (1989) produced similar conclusions. In all, six small populations were found, all on the steep, lakeward-facing slopes or grassland blowouts of the secondary dunes. No plants were observed on the beach and foredune complexes still rebuilding since the high-water levels of 1986 and 1987.
Dobberpuhl and Gibson (1987) stated that in Wisconsin, the plant is found in three habitats: (1) dry sand of partially-stabilized dunes along Lake Michigan, (2) dry, open areas of loose sand (sand blowouts) behind the main foredune and infrequently on (3) low, moist to wet beaches. Colonies thrive best in situations where the dunes are somewhat stabilized, in various slope aspects and degrees of steepness. Two populations in Wisconsin are at the mouths of creeks, where continual sand deposition from the creeks provides new habitat and increasing site longevity (WI NHP 1990, Dobberpuhl and Gibson 1987). Associated plants species in Wisconsin include Agropyron dasystachyum, Calamovilfa longifolia var. magna, Elymus canadensis, Ammophila breviligulata, Agropyron trachycaulon, Artemisia caudata, Lathyrus maritimus, Oenothera parviflora, Potentilla anserina and Solidago gillmani (WI NHP 1990, Alverson 1979, Johnson and Iltis 1963).
In Canada, C. pitcheri is found only in Ontario on sandy beaches and dunes of the shores of Lake Huron and Georgian Bay (Moore and Frankton 1974) and Lake Superior (Keddy and Keddy 1984, Keddy 1981). At Lake Superior sites in Pukaskwa National Park, plants grow approximately 1-2 meters above the lake level on gently sloping sand beaches in three distinct habitats: 1) grass (dominated by Ammophila breviligulata and Equisetum variegatum), 2) debris (dominated by Prunus pumila and Festuca saximontana) and 3) shrub (dominated by Juniperus horizontalis and Arctostaphylos uva-ursi) (Keddy and Keddy 1984, Keddy 1981). Most plants (79%) were found in the grass habitat, with 21% growing in the debris habitat. Less than 1% were found in the shrub habitat.
Pitcher's thistle is a regional endemic restricted to the dune habitats in the western Great Lakes region (USFWS 1987, Dobberpuhl and Gibson 1987, Keddy and Keddy 1984, Loveless 1983, Guire and Voss 1963). The species is a colonizer on open dune ridges, dune blowouts, and along disturbed sites in sand dunes, but is found on stabilized grassy sand terraces, sandy gravel flats and dune valleys as well (Loveless 1983). In all habitat types, however, the species appears to establish itself only in very open, sandy soil (Loveless 1983).
McEachern et al. (1989) described the habitats associated with the lakeshores as: 1) extremely exposed open communities on lake level foredunes and dune bluff edges dominated by Ammophila breviligulata, 2) transitional communities dominated by three dune grasses, A. breviligulata, Calamovilfa longifolia and Schizachyrium scoparium, and 3) stabilized inland blowouts characterized by S. scoparium/C. longifolia codominance and moderate vegetation and litter accumulation. These three habitat types mark a successional gradient, in which A. breviligulata, adapted to high rates of sand deposition occurring in the shoreline habitats, is replaced by the more competitive C. longifolia and finally, S. scoparium in progressively stable inland areas (McEachern et al. 1989). Associated with this change in dominant vegetation along a shoreline to inland transect, there is an equally significant reduction in the percentage of bare ground. This amount of bare ground is apparently significant, for it is in the most stable, S. scoparium dominated areas that C. pitcheri is the least abundant (McEachern et al. 1989).
In Michigan, C. pitcheri is most common along the northern and northeastern shore of Lake Michigan, although small populations are known from the southeastern shores of Lake Michigan and northern Lake Huron (Crispin and Penskar 1990). A few populations also occur along Lake Superior. Cirsium pitcheri typically grows in association with Ammophila breviligulata, Schizachyrium scoparium, Arabis lyrata, Arctostaphylos uva-ursi, Calamovilfa longifolia and Agropyron dasystachyum (Crispin and Penskar 1990, MI NFI 1990). At disturbed sites, Asclepias syriaca may be present (Crispin and Penskar 1990).
At Sleeping Bear Dunes National Lakeshore in Michigan, the species is apparently doing well, even in the intensely utilized areas around the marina (Hazlett and van de Kopple 1983). A recent survey by McEachern et al. (1989) found that C. pitcheri was occupying much of its potential habitat: foredunes, blowouts, dune ridges, valleys and slopes. Although C. pitcheri was least common from the backslopes of inland dunes, localized populations were found there as well.
On the Manitou Islands portion of Sleeping Bear Lakeshore, plants have been found on perched (260 feet above Lake Michigan, on glacial moraines) and coastal dunes. McEachern et al. (1989) found that plants growing on the dunes of South Manitou Island appeared more stunted and were more dispersed than those on the mainland, possibly reflecting the harsher environment of the island. Associates on a gravel lag behind a coastal dune complex at Dimmick's Point on North Manitou Island include Agropyron dasystachyum, Schizachyrium scoparium, Anemone multifida, Artemisia caudata, Betula papyrifera, Campanula rotundifolia, Carex garberi, Thuja occidentalis and Zygadenus glaucus with an overstory of Betula papyrifera. Associates in a dune blowout on South Manitou include Schizachyrium scoparium, Anemone multifida, Arctostaphylos uva-ursi, Arenaria stricta, Aster sp., Calamovilfa longifolia, Coreopsis palmata, Equisetum hyemale, Ostrya virginiana, Polygonatum pubescens, Prunus virginiana, Trientalis borealis, Trillium grandiflorum, Viburnum acerifolium, Viola canadensis and Viola sp. (Hazlett and van de Kopple 1983). For additional habitat information pertinent to Sleeping Bear National Lakeshore, see McEachern et al. (1989), Hazlett (1986) and Loveless (1983).
At Grand Sable Dunes within the Pictured Rocks National Lakeshore of Michigan, McEachern et al. (1989) found the populations occupying dune and blowout habitats ranging from the dune bluff inland to wooded areas. In contrast to Sleeping Bear, populations were scattered and were far less abundant. For habitat information concerning populations at Pictured Rocks National Lakeshore, see McEachern et al. (1989).
Within the state of Indiana, plants have been observed on dunes, foredunes, blowouts and beaches along Lake Michigan (IN NHP 1989). At the Indiana Dunes National Lakeshore, Bowles et al. (1985) found Cirsium pitcheri restricted to early and mid-successional blowouts on the high dunes adjacent to Lake Michigan. It appeared to be absent from the first foredune. Sites were extremely well-drained and support sparse dry sand prairie-like communities (Bowles et al. 1985). A recent survey of the site by McEachern et al. (1989) produced similar conclusions. In all, six small populations were found, all on the steep, lakeward-facing slopes or grassland blowouts of the secondary dunes. No plants were observed on the beach and foredune complexes still rebuilding since the high-water levels of 1986 and 1987.
Dobberpuhl and Gibson (1987) stated that in Wisconsin, the plant is found in three habitats: (1) dry sand of partially-stabilized dunes along Lake Michigan, (2) dry, open areas of loose sand (sand blowouts) behind the main foredune and infrequently on (3) low, moist to wet beaches. Colonies thrive best in situations where the dunes are somewhat stabilized, in various slope aspects and degrees of steepness. Two populations in Wisconsin are at the mouths of creeks, where continual sand deposition from the creeks provides new habitat and increasing site longevity (WI NHP 1990, Dobberpuhl and Gibson 1987). Associated plants species in Wisconsin include Agropyron dasystachyum, Calamovilfa longifolia var. magna, Elymus canadensis, Ammophila breviligulata, Agropyron trachycaulon, Artemisia caudata, Lathyrus maritimus, Oenothera parviflora, Potentilla anserina and Solidago gillmani (WI NHP 1990, Alverson 1979, Johnson and Iltis 1963).
In Canada, C. pitcheri is found only in Ontario on sandy beaches and dunes of the shores of Lake Huron and Georgian Bay (Moore and Frankton 1974) and Lake Superior (Keddy and Keddy 1984, Keddy 1981). At Lake Superior sites in Pukaskwa National Park, plants grow approximately 1-2 meters above the lake level on gently sloping sand beaches in three distinct habitats: 1) grass (dominated by Ammophila breviligulata and Equisetum variegatum), 2) debris (dominated by Prunus pumila and Festuca saximontana) and 3) shrub (dominated by Juniperus horizontalis and Arctostaphylos uva-ursi) (Keddy and Keddy 1984, Keddy 1981). Most plants (79%) were found in the grass habitat, with 21% growing in the debris habitat. Less than 1% were found in the shrub habitat.
Ecology
Cirsium pitcheri is closely related to C. canescens, a thistle of the sand hills of the Great Plains (Ownbey and Hsi 1963). Recent electrophoretic evidence has shown that the thistles share the same genetic loci, but differ greatly in the level of genetic diversity (Loveless and Hamrick 1988). Cirsium pitcheri possesses a much reduced level of genetic variability than does C. canescens, suggesting derivative-progenitor relationship, respectively. It is believed that Pitcher's thistle migrated to the Great Lakes region soon after the close of the Wisconsinan glaciation and that its reduced genetic diversity is a result of repeated and prolonged population bottlenecks (Loveless and Hamrick 1988).
Seed germination in C. pitcheri has been observed during June in Ontario (Keddy and Keddy 1984, Keddy 1981), Michigan and Indiana (McEachern et al. 1989). Keddy and Keddy (1984) found that the highest seedling mortality typically occurred in sand substrates, with the lowest in substrate of debris. In a season of drought, Ziemer (pers. comm.) still found seedling survivorship in the species to be fairly high (roughly 40%). Seedling survivorship in her study was found to be highest of the lakeward side of the foredune where active sand deposition and associated grasses (Ammophila and Calamovilfa) were common. Although Keddy and Keddy (1984) found that mortality did not significantly differ between seedlings growing in clusters or individually, Ziemer (pers. comm.) arrived at different conclusions. In her study, seedling survivorship was found to be highest in areas where other seedlings occurred.
Once established in the rosette form, mortality is low (Keddy and Keddy 1984). This is, in part, due to the fact that immature plants can withstand burial by up to 15 cm of sand (Weller in litt.) and possess taproots that often reach down 5 to 7 feet, to where available moisture lies (Pepoon 1927). Of 193 rosettes studied in Ontario by Keddy and Keddy (1984), only seven died (due in part to caribou trampling and human intervention). Plume moth (Platyptilia carduidactyla) larvae occur within the centers of rosettes but do not appear to cause mortality (Keddy and Keddy 1984). They can, however, cause injury to the apical meristem of the plant, resulting in a multi-branched parental plant.
Cirsium pitcheri is a monocarpic species which exists in a rosette for 5-8 years, flowers the following year, then dies (Crispin and Penskar 1990, McEachern et al. 1989, Dobberpuhl and Gibson 1987). Plants can remain in the rosette form until enough resources have been obtained in the root system to fuel the bolting plant and subsequent seed production (Keddy and Keddy 1984). The proportion of juvenile to adult plants is not unexpectedly skewed in favor of juvenile plants, 71.8% : 28.2% in Door County and 69.8% : 31.2% in Manitowoc County, Wisconsin (Dobberpuhl and Gibson 1987).
According to Keddy and Keddy (1984) in Ontario, plants in grassland habitat dominated by beach grass and horsetail produced over twice as many branches and flower heads than plants in the debris habitat or on a crescent beach. Those on the crescent beach were nearly all vertical. This branched growth form may be attributed to the abundance of plume moth (Platyptilia carduidactyla) larvae in the grass habitat (Keddy and Keddy 1984). Attacks, by these larvae typically result in multi-branched individuals, as discussed above.
Growth of C. pitcheri plants is also hindered at times by spittlebugs which lay eggs in the meristems of the plants, damaging newly-forming leaves (Crispin and Penskar 1990). This apparently causes mortality in some plants.
Flowering begins in late June, peaks in late July, then declines rapidly (McEachern et al. 1989, Loveless 1983). According to Loveless (1983), many plants are dead and dying by early August, but some continue flowering until mid-September. After four to seven days of blooming, flowers begin to wither and die (Keddy 1981). As flowers brown, the involucral bracts gradually close in around them, protecting developing seeds. Flower heads per stalk vary from two to as many as 125 (Keddy 1981).
Flower tubes of C. pitcheri contain several micro-liters of sweet-scented nectar secreted by a ridge at the base of the style (Keddy 1981, Knuth 1908). Apparently, a wide array of potential pollinators are attracted to this nectar. Of the 10 species of insects listed as flower visitors in Ontario (Keddy and Keddy 1984) and 23 insect visitors observed by Loveless (1983) in Michigan, only one species was the same, a bumblebee (Bombus perplexus). Insect pollen vectors include species within the genus Bombus (bumble-bees), Megachile (megachilid bees), Melissodes (anthophorid bees), Lasioglossum (small halictid bees), Agapostemon (large halictid bees), and butterflies and skippers of several genera (Loveless 1983). Other visitors to the flowers include flies, wasps, honeybees and sedentary beetles and bugs (Loveless 1983). Keddy and Keddy (1984) listed lepidopterans, dipterans and hymenopterans as flower visitors in Ontario, the most abundant of which was Bombus vagans. Prominent butterfly pollinators included Vanessa cardui and Daneus peleyippus (Crispin and Penskar 1990). Nocturnal visitors have not been studied, but moths are believed to visit the flowers (Loveless 1983). For a species list of known pollen vectors and flower visitors, see Loveless (1983) and Keddy and Keddy (1984).
Seed set is known to decline between late July and August in C. pitcheri. This decline in seed set has been attributed, in part, to pollinator availability which parallels this decline (Loveless 1983). Loveless (1983) observed that many plants died prior to maturing a single flower head, suggesting that the species allocates its resources early in the season when the likelihood of maturing fruits is highest.
The artichoke plume moth (Platyptilia carduidactyla) larvae feed on the immature seeds of C. pitcheri, sometimes causing flower mortality (McEachern et al. 1989, Keddy and Keddy 1984). This insect has been observed by Loveless (1983) in Michigan, Keddy and Keddy (1984) in Ontario, and Dobberpuhl and Gibson (1987) in Wisconsin. In Ontario, Keddy and Keddy (1984) found that most plants were affected by the moth only in July, with predation highest in a grass habitat. Fewer plants were infected in a habitat of debris, while predation was non-existent in a crescent beach population. Loveless (1983), however, found that levels of seed damage in various habitats were nearly equal, suggesting that seed predation was density-dependant. In addition, Loveless observed that seed predation in Michigan did not markedly change throughout the season. For a brief description of the plume moth life cycle, see Keddy (1981). McEachern (pers. comm.) stated that she had observed a larva within the flower head in Michigan but is unsure as to its identity at this time.
Mosquin et al. (1986) suggested that the presence of the plume moth in C. pitcheri populations may be mutually beneficial. Presence of larvae in the rosettes of C. pitcheri causes the plant to become multi-branched (Keddy and Keddy 1984). As a consequence, more flowers and seeds are produced. At present, there is little information to substantiate this hypothesis. In addition, the moth is also known to feed on the seeds of the thistle, so there may be a simple trade off or net loss of seed production despite the multiple-branched stemming of the plant. Keddy and Keddy (1984), in fact, suggested that up to 40% of the normal seed crop was lost in a given year in Ontario as a result of the moth predation.
American goldfinches were observed to devour approximately 50% of the seeds within a given flowerhead (Loveless 1984). Other birds, primarily sparrows, forage on unburied seeds. The thirteen-lined ground squirrel (Spermophilus tridecemlineatus) is also known to prey on undispersed seed.
Seeds are brown to purplish-brown, smooth, shiny, crescent-shaped achenes, measuring 7 mm X 2.5 mm (Keddy 1981). A pappus (an inverted cone of 55-65 fine hairs) is attached to the end of the achenes and aids in wind dispersal.
Dispersal of seeds is also accomplished through burial of the entire receptacle (Keddy and Keddy 1984). The pappi are delicately attached to the fruits and are easily broken off, so most seeds remain intact within the seed heads (Keddy and Keddy 1984). These seed heads may remain attached to parental plants and become buried as they die and fall over (McEachern et al. 1989), or break off from the plant (Keddy and Keddy 1984). Seed dispersal by entire seed head greatly increases the likelihood that seeds will fall a short distance from the parent, into favorable habitat (Keddy and Keddy 1984). Ziemer (pers. comm.) found that the vast majority of seeds fell within 0.5-1.0 m from the parental plant. Long-distance dispersal is apparently not common (Ziemer pers. comm.) but may be accomplished primarily through the wave action (Keddy and Keddy 1984). Seed dispersal begins in late July and early August in Ontario (Keddy 1981).
Density of C. pitcheri populations within Indiana Dunes National Lakeshore has been recently estimated. Within Indiana Dunes State Park, an estimate of 230 plants/ha with a 1:1 ratio of adults to juveniles was determined, while estimates of 1070 plants/ha with a 8.8:1 ratio of juvenile to adult plants were recorded at Miller. Nine adults and 69 juveniles were counted at Keiser (Bowles et al. 1985).
Seed germination in C. pitcheri has been observed during June in Ontario (Keddy and Keddy 1984, Keddy 1981), Michigan and Indiana (McEachern et al. 1989). Keddy and Keddy (1984) found that the highest seedling mortality typically occurred in sand substrates, with the lowest in substrate of debris. In a season of drought, Ziemer (pers. comm.) still found seedling survivorship in the species to be fairly high (roughly 40%). Seedling survivorship in her study was found to be highest of the lakeward side of the foredune where active sand deposition and associated grasses (Ammophila and Calamovilfa) were common. Although Keddy and Keddy (1984) found that mortality did not significantly differ between seedlings growing in clusters or individually, Ziemer (pers. comm.) arrived at different conclusions. In her study, seedling survivorship was found to be highest in areas where other seedlings occurred.
Once established in the rosette form, mortality is low (Keddy and Keddy 1984). This is, in part, due to the fact that immature plants can withstand burial by up to 15 cm of sand (Weller in litt.) and possess taproots that often reach down 5 to 7 feet, to where available moisture lies (Pepoon 1927). Of 193 rosettes studied in Ontario by Keddy and Keddy (1984), only seven died (due in part to caribou trampling and human intervention). Plume moth (Platyptilia carduidactyla) larvae occur within the centers of rosettes but do not appear to cause mortality (Keddy and Keddy 1984). They can, however, cause injury to the apical meristem of the plant, resulting in a multi-branched parental plant.
Cirsium pitcheri is a monocarpic species which exists in a rosette for 5-8 years, flowers the following year, then dies (Crispin and Penskar 1990, McEachern et al. 1989, Dobberpuhl and Gibson 1987). Plants can remain in the rosette form until enough resources have been obtained in the root system to fuel the bolting plant and subsequent seed production (Keddy and Keddy 1984). The proportion of juvenile to adult plants is not unexpectedly skewed in favor of juvenile plants, 71.8% : 28.2% in Door County and 69.8% : 31.2% in Manitowoc County, Wisconsin (Dobberpuhl and Gibson 1987).
According to Keddy and Keddy (1984) in Ontario, plants in grassland habitat dominated by beach grass and horsetail produced over twice as many branches and flower heads than plants in the debris habitat or on a crescent beach. Those on the crescent beach were nearly all vertical. This branched growth form may be attributed to the abundance of plume moth (Platyptilia carduidactyla) larvae in the grass habitat (Keddy and Keddy 1984). Attacks, by these larvae typically result in multi-branched individuals, as discussed above.
Growth of C. pitcheri plants is also hindered at times by spittlebugs which lay eggs in the meristems of the plants, damaging newly-forming leaves (Crispin and Penskar 1990). This apparently causes mortality in some plants.
Flowering begins in late June, peaks in late July, then declines rapidly (McEachern et al. 1989, Loveless 1983). According to Loveless (1983), many plants are dead and dying by early August, but some continue flowering until mid-September. After four to seven days of blooming, flowers begin to wither and die (Keddy 1981). As flowers brown, the involucral bracts gradually close in around them, protecting developing seeds. Flower heads per stalk vary from two to as many as 125 (Keddy 1981).
Flower tubes of C. pitcheri contain several micro-liters of sweet-scented nectar secreted by a ridge at the base of the style (Keddy 1981, Knuth 1908). Apparently, a wide array of potential pollinators are attracted to this nectar. Of the 10 species of insects listed as flower visitors in Ontario (Keddy and Keddy 1984) and 23 insect visitors observed by Loveless (1983) in Michigan, only one species was the same, a bumblebee (Bombus perplexus). Insect pollen vectors include species within the genus Bombus (bumble-bees), Megachile (megachilid bees), Melissodes (anthophorid bees), Lasioglossum (small halictid bees), Agapostemon (large halictid bees), and butterflies and skippers of several genera (Loveless 1983). Other visitors to the flowers include flies, wasps, honeybees and sedentary beetles and bugs (Loveless 1983). Keddy and Keddy (1984) listed lepidopterans, dipterans and hymenopterans as flower visitors in Ontario, the most abundant of which was Bombus vagans. Prominent butterfly pollinators included Vanessa cardui and Daneus peleyippus (Crispin and Penskar 1990). Nocturnal visitors have not been studied, but moths are believed to visit the flowers (Loveless 1983). For a species list of known pollen vectors and flower visitors, see Loveless (1983) and Keddy and Keddy (1984).
Seed set is known to decline between late July and August in C. pitcheri. This decline in seed set has been attributed, in part, to pollinator availability which parallels this decline (Loveless 1983). Loveless (1983) observed that many plants died prior to maturing a single flower head, suggesting that the species allocates its resources early in the season when the likelihood of maturing fruits is highest.
The artichoke plume moth (Platyptilia carduidactyla) larvae feed on the immature seeds of C. pitcheri, sometimes causing flower mortality (McEachern et al. 1989, Keddy and Keddy 1984). This insect has been observed by Loveless (1983) in Michigan, Keddy and Keddy (1984) in Ontario, and Dobberpuhl and Gibson (1987) in Wisconsin. In Ontario, Keddy and Keddy (1984) found that most plants were affected by the moth only in July, with predation highest in a grass habitat. Fewer plants were infected in a habitat of debris, while predation was non-existent in a crescent beach population. Loveless (1983), however, found that levels of seed damage in various habitats were nearly equal, suggesting that seed predation was density-dependant. In addition, Loveless observed that seed predation in Michigan did not markedly change throughout the season. For a brief description of the plume moth life cycle, see Keddy (1981). McEachern (pers. comm.) stated that she had observed a larva within the flower head in Michigan but is unsure as to its identity at this time.
Mosquin et al. (1986) suggested that the presence of the plume moth in C. pitcheri populations may be mutually beneficial. Presence of larvae in the rosettes of C. pitcheri causes the plant to become multi-branched (Keddy and Keddy 1984). As a consequence, more flowers and seeds are produced. At present, there is little information to substantiate this hypothesis. In addition, the moth is also known to feed on the seeds of the thistle, so there may be a simple trade off or net loss of seed production despite the multiple-branched stemming of the plant. Keddy and Keddy (1984), in fact, suggested that up to 40% of the normal seed crop was lost in a given year in Ontario as a result of the moth predation.
American goldfinches were observed to devour approximately 50% of the seeds within a given flowerhead (Loveless 1984). Other birds, primarily sparrows, forage on unburied seeds. The thirteen-lined ground squirrel (Spermophilus tridecemlineatus) is also known to prey on undispersed seed.
Seeds are brown to purplish-brown, smooth, shiny, crescent-shaped achenes, measuring 7 mm X 2.5 mm (Keddy 1981). A pappus (an inverted cone of 55-65 fine hairs) is attached to the end of the achenes and aids in wind dispersal.
Dispersal of seeds is also accomplished through burial of the entire receptacle (Keddy and Keddy 1984). The pappi are delicately attached to the fruits and are easily broken off, so most seeds remain intact within the seed heads (Keddy and Keddy 1984). These seed heads may remain attached to parental plants and become buried as they die and fall over (McEachern et al. 1989), or break off from the plant (Keddy and Keddy 1984). Seed dispersal by entire seed head greatly increases the likelihood that seeds will fall a short distance from the parent, into favorable habitat (Keddy and Keddy 1984). Ziemer (pers. comm.) found that the vast majority of seeds fell within 0.5-1.0 m from the parental plant. Long-distance dispersal is apparently not common (Ziemer pers. comm.) but may be accomplished primarily through the wave action (Keddy and Keddy 1984). Seed dispersal begins in late July and early August in Ontario (Keddy 1981).
Density of C. pitcheri populations within Indiana Dunes National Lakeshore has been recently estimated. Within Indiana Dunes State Park, an estimate of 230 plants/ha with a 1:1 ratio of adults to juveniles was determined, while estimates of 1070 plants/ha with a 8.8:1 ratio of juvenile to adult plants were recorded at Miller. Nine adults and 69 juveniles were counted at Keiser (Bowles et al. 1985).
Terrestrial Habitats
Grassland/herbaceousSand/dune
Other Nations (2)
CanadaN2
| Province | Rank | Native |
|---|---|---|
| Ontario | S2 | Yes |
United StatesN3
| Province | Rank | Native |
|---|---|---|
| Illinois | S1 | Yes |
| Wisconsin | S2 | Yes |
| Michigan | S3 | Yes |
| Indiana | S1 | Yes |
Threat Assessments
| Threat | Scope | Severity | Timing |
|---|---|---|---|
| 1 - Residential & commercial development | Restricted (11-30%) | Moderate or 11-30% pop. decline | High (continuing) |
| 1.3 - Tourism & recreation areas | Restricted (11-30%) | Moderate or 11-30% pop. decline | High (continuing) |
| 3 - Energy production & mining | Restricted (11-30%) | Moderate or 11-30% pop. decline | High - moderate |
| 3.2 - Mining & quarrying | Restricted (11-30%) | Moderate or 11-30% pop. decline | High - moderate |
| 4 - Transportation & service corridors | Large - restricted | Moderate or 11-30% pop. decline | High - moderate |
| 4.1 - Roads & railroads | Large - restricted | Moderate or 11-30% pop. decline | High - moderate |
| 6 - Human intrusions & disturbance | Large - restricted | Moderate or 11-30% pop. decline | High (continuing) |
| 6.1 - Recreational activities | Large - restricted | Moderate or 11-30% pop. decline | High (continuing) |
| 6.3 - Work & other activities | Restricted (11-30%) | Moderate or 11-30% pop. decline | High - moderate |
| 7 - Natural system modifications | Large (31-70%) | Moderate or 11-30% pop. decline | Moderate - low |
| 7.1 - Fire & fire suppression | Large (31-70%) | Moderate or 11-30% pop. decline | Moderate - low |
| 8 - Invasive & other problematic species, genes & diseases | Pervasive (71-100%) | Moderate or 11-30% pop. decline | High - low |
| 8.1 - Invasive non-native/alien species/diseases | Pervasive (71-100%) | Moderate or 11-30% pop. decline | High - moderate |
| 8.2 - Problematic native species/diseases | Large - restricted | Moderate or 11-30% pop. decline | High (continuing) |
| 8.3 - Introduced genetic material | Large - restricted | Moderate or 11-30% pop. decline | High (continuing) |
Plant Characteristics
DurationBIENNIAL
Economic Value (Genus)No
Roadless Areas (5)
Michigan (5)
| Area | Forest | Acres |
|---|---|---|
| Bear Swamp | Huron-Manistee National Forest | 3,915 |
| Delirium | Hiawatha National Forest | 190 |
| Fibre | Hiawatha National Forest | 7,432 |
| Government Island | Hiawatha National Forest | 225 |
| Round Island | Hiawatha National Forest | 2 |
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