Rock-tansy - Sphaeromeria capitata
Tanacetum capitatum, Artemisia capitata
(see State Rank Reason below)
MNPS Threat Rank
State Rank Reason (see State Rank above)
This species is a regional endemic with limited distribution in limestone foothills of southwest Montana (upper Beaverhead River drainage) and Pryor Mts - Big Horn Canyon. It is reported to be locally common in the Big Horn Canyon area (Lesica & Shelly, 1991)
- Details on Status Ranking and Review
Score0-1 - Moderate to Large: Population size is imprecisely known but is believed to be >10,000 individuals.
Score2 - Regional or State Endemic or Small Montana Range: Generally restricted to an area <100,000 sq. miles (equivalent to 2/3 the size of Montana or less) or Montana contributes 50% or more of the species’ range or populations OR limited to 2-3 Sub-basins in Montana.
Area of Occupancy
Score1 - Moderate: Generally occurring in 11-25 Subwatersheds (6th Code HUC’s).
Score1 - Moderate: Species is restricted to a specific habitat that is more widely distributed or to several restricted habitats and is typically dependent upon relatively unaltered, good-quality habitat (C Values of 5-7).
ScoreNA - Rank factor not assessed.
Score0-1 - Low to Medium.
Score0 - Low Vulnerability: Species does not have any unusual or specific life history or biological attributes or limted reproductive potential which makes it susceptible to extirpation from stochastic events or other adverse impacts to its habitat and thus slow to recover.
Raw Conservation Status Score
4 to 6 total points scored out of a possible 16 (Rarity factors and threats only).
Stems erect, 2–15 cm. Leaves 8–25 mm long, deeply lobed into linear segments. Inflorescence capitate. Involucre 2–3 mm high; phyllaries 5 to 8, tomentose. Disk corollas 1–3 mm long. Achenes 1–2 mm long (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)
Flowers from late May through early July.
Recent research supports the placement of Sphaeromeria in Artemisia (Garcia et.al. 2011).
This species is known from Wyoming, southwestern Montana, northwestern Colorado, and disjunct onto the Utah Plateaus in Garfield Co, Utah (Cronquist et al. 1994).
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
Shallow, limestone-derived soil on rock outcrops in exposed sagebrush grassland, desert shrubland, and juniper woodland in the valley and foothill zones.
Ecological Systems Associated with this Species
- Additional ReferencesLegend: View Online Publication
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- Garcia, Sònia, Teresa Garnatje, E. Durant McArthur, Jaume Pellicer, Stewart C. Sanderson, and Joan Vallès. 2011. Taxonomic and Nomenclatural Rearrangements in Artemisia Subgen. Tridentatae, Including a Redefinition of Sphaeromeria (Asteraceae, Anthemideae). Western North American Naturalist. 71 (2): 158-163.
- Lesica, P. and P.L. Achuff. 1992. Distribution of vascular plant species of special concern and limited distribution in the Pryor Mountain desert, Carbon County, Montana. Unpublished report to the Bureau of Land Management. Montana Natural Heritage Program, Helena, MT. 105 pp.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- Vanderhorst, J.P. and P. Lesica. 1994. Sensitive plant survey in the Tendoy Mountains, Beaverhead County, Montana. Unpublished report to the Bureau of Land Management, Butte District. Montana Natural Heritage Program, Helena, MT. 59 pp. plus appendices.