Part 1 COSSARO candidate species at risk evaluation form – June 2010

Dense Blazing Star (Liatris spicata)

Current designations:

GRANKG5 (NatureServe 2010)
NRANK Canada – N2 (NatureServe 2010)
COSEWIC – Threatened (April 2010)
SARA – Threatened, Schedule 1
General Status Canada – At Risk (2005)
ESA 2007 – Threatened (previously assessed by COSSARO as Threatened in February 2001)
SRANKS2 (NatureServe 2010)
General Status Ontario – At Risk (2005)

Distribution and status outside Ontario:

Dense Blazing Star is endemic to eastern North America. It has a wide distribution, occurring from New York to Florida, and westward to the Mississippi. Southwestern Ontario is at the northern limit of the species' range. The sole Quebec report is based on an introduction (Scoggan 1979).

Eligibility criteria

Native status

✔ Yes. Native in southwestern Ontario prairie remnants. Also a showy and popular horticultural species which is widely cultivated. Some populations along railways and roadsides away from southwestern Ontario are probably adventive or escapes from cultivation.

Taxonomic distinctness

✔ Yes. Considered a valid species in all recent taxonomic treatments. Two varieties are recognized, the one occurring in Ontario is var. spicata.

Designatable units

Native populations are known in the province only from southwestern Ontario, with no major disjunctions in range. No genetic data are available on Ontario populations.

Priority-setting criteria

Recent arrival

✔ No. Long known as a native plant of southwestern Ontario prairies, where collected as early as 1901.


✔ No.

Primary criteria (rarity and declines)

  1. Global rank

    ✔ Not in any category. G5.

  2. Global decline

    ✔ Not in any category. No evidence of a major global decline.

  3. Northeastern North America ranks

    ✔ not in any category. Highly ranked (S1, S2, SH or SX) in 3 of 14 northeastern jurisdictions in which it occurs natively (21%). Ranked S3 in two other jurisdictions (WI, WV). See Appendix 1.

  4. Northeastern North America decline

    ✔ Not in any category. No evidence of a major decline in northeastern North America.

  5. Ontario occurrences

    ✔ Threatened. There are 10-12 extant Element Occurrences in Ontario (COSEWIC 2010; NHIC). Two sites were not checked during fieldwork for the recent COSEWIC update status report (so may or may not still be extant).

  6. Ontario decline

    ✔ Threatened. Virtually all sites checked in 2008 for which previous (1986 or 2001) population counts are estimates are available, have declined (Table 1 in COSEWIC 2010). Twelve of 25 (48%) Element Occurrence records in the NHIC database are considered extirpated and at least a couple of others have not been recently checked and may be extirpated.

  7. Ontario’s conservation responsibility

    ✔ Not in any category. Ontario makes up <10% of the species global range (COSEWIC 2010).

Secondary criteria (threats and vulnerability)

  1. Population sustainability

    ✔ insufficient information. There is no information on population sustainability in Ontario or elsewhere for Dense Blazing Star.

  2. Lack of regulatory protection for exploited wild populations

    ✔ not in any category. This species is not exploited in Ontario. However, Liatris spicata can be used in gardening and seeds of this plant can be purchased. Presently there is no evidence to suggest that the taking of wild plants for such purposes poses a threat to the persistence of the species in Ontario, however the situation may change as the horticulture of native plant species continues to increase in popularity.

  3. Human threats

    ✔ Endangered. The prairie and savannah habitat of several Ontario occurrences of Liatris spicata is at risk due to increased urbanization in the Windsor - La Salle area, fire suppression, and the conversion of land to agriculture. Encroachment by woody species, lack of frequent fires, invasive species (particularly Phragmites australis), management practices (mowing, site alteration, vegetation control), trampling, wildflower picking, erosion from ship wakes, herbicides, and genetic contamination from adventive hybrids are all threats (COSEWIC 2010). Since one or more of these threats is probably affecting the species at most, if not all, Ontario sites, this criterion was assessed as Endangered. The construction of a proposed expressway and bridge close to Ojibway Prairie could result in the loss of a large number of individuals.

  4. Specialized life history or habitat-use characteristics

    ✔ Threatened. Although the species infrequently occurs in wetland interdunal meadows, old fields, and along railways, Liatris spicata is largely a species of provincially-rare tallgrass prairie habitats. In Ontario it grows in at least four globally and provincially rare tallgrass prairie, savannah and woodland vegetation types: Moist-Fresh Tallgrass Prairie Type (G2 S1); Moist-Fresh Pin Oak - Bur Oak Tallgrass Savannah Type (G1 S1); Moist-Fresh Black Oak Tallgrass Savannah Type (G2 S1); and Moist-Fresh Black Oak - White Oak Tallgrass Woodland Type (G2 S1) (W.D. Bakowsky pers. comm. February 2001; Brodribb and Oldham 2001). Tallgrass prairie is a highly threatened and declining vegetation type in Ontario and elsewhere and is the focus of considerable conservation attention in the province (e.g. Rodger 1998). Dense Blazing Star is a shade intolerant species that requires disturbance (fire or flooding) to persist at a location. Most remaining populations do not occur on land that is managed to maintain the conditions necessary for prairie species.

COSSARO criteria met (primary/secondary)

  • Endangered – 0/1
  • Threatened – 2/1
  • Special concern – 0/0


Dense Blazing Star is a rare and declining species in Ontario which is dependent on provincially-rare prairie and savannah habitats. The species is threatened because of its restricted distribution, continued decline in the number and quality of extant occurrences, and the loss of habitat due to agriculture, urban development and fire cessation. Other identified threats include invasive species (particularly Phragmites australis), management practices (mowing, site alteration, vegetation control), trampling, wildflower picking, erosion from ship wakes, herbicides, and genetic contamination from adventive hybrids However the species still occurs in 10 to 12 Ontario sites, some of which are protected, and there are still an estimated 60,000 to 70,000 mature individuals in the province.

Information sources

Argus, G.W., K.M. Pryer, D.J. White and C.J. Keddy (eds.). 1982-1987. Atlas of the Rare Vascular Plants of Ontario. Botany Division, National Museum of National Sciences, Ottawa.

Brodribb, K.E., and M.J. Oldham. 2001. COSSARO Candidate V, T, E Species Evaluation Form for Dense Blazing Star (Liatris spicata). Committee on the Status of Species At Risk in Ontario. February 2001, updated April 2001. 12 pp.

Cochrane, T.S., and H.H. Iltis. 2000. Atlas of the Wisconsin Prairie and Savanna Flora. Technical Bulletin No. 191, Department of Natural Resources, Madison, Wisconsin. 226 pp.

COSEWIC. 2010. Update COSEWIC Status Report on Dense Blazing Star Liatris spicata. Committee on the Status of Endangered Wildlife in Canada, Ottawa. Two-month Interim Report (February 2010). 24 pp.

Fisher, T.R. 1988. The Dicotyledoneae of Ohio. Part 3: Asteraceae. Ohio State University Press, Columbus. 280 pp.

Harvill, Jr., A.M., T.R. Bradley and C.E. Stevens. 1981. Atlas of the Virginia Flora. Part Ⅱ: Dicotyledons. Virginia Botanical Associates, Farmville, Virginia. 148 pp.

Magee, D.W., and H.E. Ahles. 1999. Flora of the Northeast: a Manual of the Vascular Flora of New England and Adjacent New York. University of Massachusetts Press, Amherst, Massachusetts. 1213 pp.

Mohlenbrock, R.H., and D.M. Ladd. 1978. Distribution of Illinois Vascular Plants. Southern Illinois University Press. 289 pp.

NatureServe. 2010. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available (Accessed: May 28, 2010).

Rodger, L. 1998. Tallgrass Communities of Southern Ontario: A Recovery Plan. World Wildlife Fund Canada, Toronto. 66 pp.

Scoggan, H.J. 1979. The Flora of Canada. Part 4: Dicotyledoneae (Loasaceae to Compositae). Publications in Botany No. 7(4). National Museum of Natural Sciences, Ottawa. 594 pp.

Voss, E.G. 1996. Michigan Flora: A Guide to the Identification and Occurrence of the Native and Naturalized Seed-Plants of the State. Part Ⅲ: Dicots (Pyrolaceae - Compositae). Cranbrook Institute of Science and University of Michigan Herbarium, Ann Arbor. 622 pp.

Wherry, E.T., J.M. Fogg, Jr. and H.A. Wahl. 1979. Atlas of the Flora of Pennsylvania. Morris Arboretum, University of Pennsylvania, Philadelphia. 390 pp.

Wild Species, 2005. General Status Search Tool. []. (Accessed May 28, 2010).

Appendix 1

Northeastern North America rank, status and decline

CTSNR (not ranked; NatureServe 2010). Magee and Ahles (1999) mention it from a single CT county (Fairfield) and suggest it is introduced from further south and west. Considered non native to CT for the purposes of this evaluation.
DES1 (NatureServe 2010).
ILSNR (not ranked; NatureServe 2010). Mapped from 20 IL counties by Mohlenbrock and Ladd (1978) and considered not of conservation concern for the purposes of this assessment.
INSNR (not ranked; NatureServe 2010).
IASNR (not ranked; NatureServe 2010).
KYS4 (NatureServe 2010).
MASNR (not ranked; NatureServe 2010). Magee and Ahles (1999) mention it from a single MA county (Middlesex) and suggest it is introduced from further south and west. Considered non native to MA for the purposes of this evaluation.
MBNot present (NatureServe 2010).
MDS1 (NatureServe 2010).
MENot present (NatureServe 2010).
MISNR (not ranked; NatureServe 2010). Widespread in southern Lower Peninsula of MI; mapped from 26 MI counties (Voss, 1996); considered not of conservation concern for the purposes of this assessment.
MNNot present (NatureServe 2010).
NBNot present (NatureServe 2010).
NFNot present (NatureServe 2010).
NJSNR (not ranked; NatureServe 2010).
NSNot present (NatureServe 2010).
NYSNA (exotic; NatureServe 2010).
NYSNR (not ranked; NatureServe 2010). Widespread; mapped from 24 OH counties (Fisher 1988); considered not of conservation concern for the purposes of this assessment.
ONS2 (NatureServe 2010).
PASNR (not ranked; NatureServe 2010). About 50 dots, mainly in SE part of state (Wherry et al. 1979); considered not of conservation concern for the purposes of this assessment.
PENot present (NatureServe 2010).
QCSNA (exotic; NatureServe 2010). One record; introduced (Scoggan 1979).
RINot present (NatureServe 2010).
VAS4 (NatureServe 2010). Mapped from 24 counties by Harvill et al. (1981).
VTNot present (NatureServe 2010).
WIS3 (NatureServe 2010). Threatened in WI (Argus et al. 1982-1987). Special Concern status in WI (Cochrane and Iltis 2000). "A rare and beautiful species …. Although once locally abundant, it is now probably threatened, because its habitat is all but swallowed up by agriculture and development….much in demand by gardeners and florists, who use it in bouquets." (Cochrane and Iltis 2000).
WVS3 (NatureServe 2010).
  • occurs natively in 14 of 27 northeastern jurisdictions (exotic in 4 others) SRANK or equivalent information available for 11 of 14 jurisdictions (79%) S1, S2, SH, or SX in 3 of 14 jurisdictions (21%)

Part 2: Ontario evaluation using COSEWIC criteria

Regional (Ontario) COSEWIC criteria assessment

Criterion A – declining population

No. Much of the historical population decline is beyond the time frame to qualify for this criterion. Population trend over the last 3 generations for most populations is unknown or below threshold levels.

Criterion B – small distribution and decline or fluctuation

Threatened (B1ab(ii,iii,iv,v)+B2ab(ii,iii,iv,v)). EO and IAO within criterion limits and with possibly only 10 extant locations with no severe fragmentation but declines in IAO, area and quality of habitat, number of populations and mature individuals have occurred.

Criterion C – small population size and decline

No. The number of Dense Blazing Star plants in Ontario is estimated to be roughly 60,000 to 70,000 mature individuals (COSEWIC 2010).

Criterion D – very small or restricted

No. Population size and IAO above criterion limits.

Criterion E – quantitative analysis

No. No quantitative analysis available.

Rescue Effect

Unlikely. Although this species is wind dispersed, it is unlikely that an immigrant propagule would be able to establish itself on suitable habitat, given the rarity and fragmented distribution of prairie and savannah communities in Ontario.