Regularity: Regularly occurring
Global Range: Endemic to high elevations of the Tushar Mountains in the Southern Utah High Plateaus of Piute and Beaver Counties, central Utah; known from at least Mount Belknap and Gold Mountain.
Differs from S. werneriifolius in its lack of ray flowers and in its broadly oblanceolate to suborbicular leaves (Utah Native Plant Society 2008, Welsh et al. 2008). Also differs from S. canus in its lack of ray flowers; in addition, S. castoreus has larger (on average) involucres and shorter basal leaves than S. canus (Welsh 1993). Other diagnostic features for S. castoreus include its entire or toothed leaves and woolly-tomentose herbage (Utah Native Plant Society 2008).
Comments: Often on windswept ridges, talus/scree slopes, and gravelly barrens above timberline, in sparsely vegetated alpine tundra communities of Polemonium viscosum, Trisetum, Festuca, and/or Arenaria; less commonly downward to the spruce-fir community. Substrate is thermally modified Tertiary igneous outcrops and gravel (hydrothermally altered intercaldera siliceous alkali rhyolite lava flows, lava domes, and ash-flow tuffs of the Mount Belknap Volcanics); these rocks are resistant to weathering, creating steep talus slopes and cliffs with limited soil development. Co-occurring species include Draba sobolifera and Draba ramulosa. 3300-3900 m.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 1 - 20
Comments: Surveys in the Fishlake National Forest in 2000 and 2001 detected this species (although their primary target was Draba sobolifera); 10 S. castoreus sites were located, with "site" defined as plants separated by > 0.25 miles (0.4 km) (D. Tait, pers. comm. 2009). Subsequently, additional S. castoreus plants were documented on private lands in the vicinity; it is not known for certain whether these plants were tallied as part of the 2000-2001 sites, but they are probably additional (D. Tait, pers. comm. 2009). Rodriguez (2006) reports that the species is known from 7 occurrences within 9-quarter sections on the Beaver Ranger District of the Fishlake National Forest. A number of mountains in the Tushar range have not yet been combed for this species, so it is possible that additional sites will be documented in the future with further survey efforts; however, the species is unlikely to be documented beyond the Tushars, as other relatively nearby mountain ranges are very different in character and appear to lack suitable habitat (D. Tait pers. comm. 2009).
National NatureServe Conservation Status
Rounded National Status Rank: N1 - Critically Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: G1 - Critically Imperiled
Reasons: Endemic to high elevations of the Tushar Mountains of Piute and Beaver Counties, central Utah. Approximately 7-10 occurrences are known, and approximately 2350 individuals have been documented. Further survey efforts may discover some additional sites within the Tushars, but it is unlikely that the species occurs beyond this mountain range. Occurrences are predominantly within the Fishlake National Forest and managed by the U.S. Forest Service; at least one is within a Research Natural Area and others may soon be within designated wilderness. Some plants have been documented on private lands in the vicinity. There are no known threats within the Fishlake National Forest at this time; however, the degree of threat to plants on private lands is unknown.
Global Short Term Trend: Unknown
Comments: Trends are very difficult to estimate, as there have not been repeat survey efforts at different timepoints as yet (D. Tait pers. comm. 2009).
Degree of Threat: Low
Comments: Currently there are no known threats to this species within the Fishlake National Forest (D. Tait, pers. comm. 2009). It occurs in high alpine, difficult-to-access areas, and there are not many threats in this part of the Tushar Range. Rocky Mountain goats are present (Taye 1995), but are not considered a threat because S. castoreus plants are small, of low palatability, and occur in very rocky, sparsely vegetated areas not preferred by the goats (D. Tait, pers. comm. 2009). In the past, ORV use was a potential threat to this species; however, the Travel Management Plan now in place for the Fishlake National Forest prohibits cross-country travel (D. Tait pers. comm. 2009). Trampling by hikers does not appear to be a threat; in general, plants are not located close to trails, and the steep relief of the substrates on which it grows discourages exploration (D. Tait pers. comm. 2009). No noticeable climate change impacts have yet been observed at these elevations, although some changes have been noted at lower elevations in this region (D Tait, pers. comm. 2009). Despite the apparent lack of threats on the Fishlake, some plants are known to occur on private lands and it is possible that they may face threats that are difficult for National Forest land managers to document or mitigate (D. Tait, pers. comm. 2009).
Relevance to Humans and Ecosystems
Stewardship Overview: This species has few management needs at this time (D. Tait pers. comm. 2009). The Travel Management Plan now in place for the Fishlake National Forest, which prohibits cross-country travel, is believed to benefit this species by eliminating ORV use in its habitat; actions to ensure and monitor compliance with this Plan could therefore be of some benefit. Also, because this species is restricted to the high alpine, monitoring for climate change impacts could be helpful.
Packera castoreus is a rare species of flowering plant in the aster family known by the common names Beaver Mountain groundsel and Beaver Mountain ragwort. It is endemic to Utah in the United States, where it occurs only in the Tushar Mountains.
This small alpine plant grows just a few centimeters tall with one or more woolly stems. The lower leaves have blades one or two centimeters long with woolly undersides. The flower heads have purple-green, woolly phyllaries and no ray florets.
There are about 7 to 10 known occurrences of this plant on the high slopes of the Tushar Mountains of central Utah, mostly within the Fishlake National Forest. It occurs on Mt. Belknap and Gold Mountain, and probably other peaks. It grows on barren talus on windy, exposed mountain slopes in alpine tundra habitat above the tree line. Other plants in the sparsely vegetated habitat include sky pilot (Polemonium viscosum), Mt. Belknap draba (Draba ramulosa), and various grasses.
Names and Taxonomy
Comments: Newly described as Senecio castoreus in 1993 (Welsh 1993). Kartesz (1999) recognizes but places in the genus Packera. The legitimacy of this taxon has been questioned by some field botanists, as the lack of ray flowers is apparently the only diagonostic feature separating it from other Senecio in the field.