CPC Plant Profile: Weber's Saw-wort
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Plant Profile

Weber's Saw-wort (Saussurea weberi)

Photo Credit: Alexandra Seglias
Description
  • Global Rank: G2 - Imperiled
  • Legal Status: N/A
  • Family: Asteraceae
  • State: CO, MT, WY
  • Nature Serve ID: 154379
  • Date Inducted in National Collection:

Weber's saw-wort is a dwarf perennial herb that is 5-20 cm high and arising from a woody rootstock. The lance-shaped leaf blades are coarsely toothed, up to 8 cm long, and have a broad petiole. The alternate leaves are crowded on the stem, reduced, and lacking petioles towards the top. Herbage is covered with long, tangled hairs when young but becomes glabrous with age. The purple flowering heads are borne in a dense array subtended by leaves at the top of the stem. The broad involucral bracts of the heads have rounded tips and are 11-15 mm long. All of the flowers are tubular (disk flowers); ray flowers are absent. The achene has a pappus on top

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Updates
Nature Serve Biotics
  • 05/02/2017

Occurs in Colorado, Wyoming, and Montana, where it is confined to small areas of suitable alpine habitat (Kartesz 1999, Fertig 2000). Between 18 and 32 occurrences. Threats include hikers, mining, and grazing by wild animals.

Hulten, Mary VB Goshorn
  • 01/01/2010

Saussurea weberi is thought to have a naturally limited range and is not known to have suffered significant population or habitat loss as a result of human activities. However, distribution information may not be complete and little is known about the bas

Hulten, Mary VB Goshorn
  • 01/01/2010

In Wyoming, populations often have thousands to tens of thousands of individuals, but are restricted to small areas of suitable habitat in the alpine (Fertig 2000). All the Colorado populations are very small (CNPS 1989). Saussurea weberi is known from 17 reported occurrences in Colorado, 14 of which are on USFS Region 2 national forests. Population sizes are reported for 12 of the 17 Colorado occurrences, with totals varying from two to several hundred individuals in 10 of the occurrences. The largest reported occurrences include the Dolly Varden Gulch site, containing approximately 4,500 individuals on private land, and the Mount Sheridan site on the Pike NF containing approximately 1,000 individuals (Glisson 2004). There are no published data on population trends. The Colorado occurrences reveal considerable variation in year to year tallies of individuals for particular sites, suggesting that year to year population variability may be high (Glisson 2004).

Hulten, Mary VB Goshorn
  • 01/01/2010

Ron Abbott, independent botanist, has on-going studies of the Horseshoe Cirque occurrence in Colorados Mosquito Range. Abbott is presently conducting the ninth year of a planned 10-year study on patterns of Saussurea weberi shoot production in the Horseshoe Cirque (Glisson 2004).

Hulten, Mary VB Goshorn
  • 01/01/2010

No specific management strategy is known. Saussurea weberi currently has no federal status under the Endangered Species Act or in Region 2 of the USDA Forest Service (USFS), but is listed as a sensitive species in USFS Regions 1 and 4, and is also listed as a sensitive species by the Bureau of Land Management in Colorado.

Hulten, Mary VB Goshorn
  • 01/01/2010

Further species inventory work is among the top priorities for research on Saussurea weberi, especially better characterization of its distribution across potential habitat in Colorado. Until its distribution and population size are better defined, it will not be possible to assess the conservation needs and priorities for this species accurately (Glisson 2004). Very little is known about the population ecology of Saussurea weberi. Population estimates are available for about half of the occurrences, but there are no monitoring data with which to determine the population trend, with the exception of Abbotts ongoing study of the Horseshoe Cirque occurrence. Basic life history parameters need to be determined from which the viability of populations can be inferred. Assessing the overall population trend across multiple occurrences is also among the top research priorities for this species. Other basic areas of study that are needed include the demography, conservation genetics, pollen cytology, molecular cytogenetics, floral biology, seed viability, and species-environment relationships, including responses to disturbance, of Saussurea weberi. Such information would have significant relevance to the conservation and management of this species.

Hulten, Mary VB Goshorn
  • 01/01/2010

Seed collection and storage.

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Nomenclature
Taxon Saussurea weberi
Authority Hultén
Family Asteraceae
CPC Number 3828
ITIS 36083
USDA SAWE
Common Names Weber's Saw-wort
Associated Scientific Names Saussurea weberi
Distribution Regional endemic of southwest Montana, northwest Wyoming, and central Colorado.
State Rank
State State Rank
Colorado S2
Montana S2
Wyoming S2
Habitat

Generally occurs on rocky, exposed limestone slopes, talus, and ridges, in high elevation, subalpine to alpine sites. Habitats include gravelly tundra slopes amid scree (often on solifluction lobes on exposed sites, with poorly developed, limestone- and dolomite-derived soils), alpine talus slopes on limestone-derived substrates, and moderately dry alpine meadows and adjacent slopes on northwest aspects, in well-developed, calcareous soils. Also occasionally found on sandstone or granite substrates. Communities include stable tundra associations on solifluction lobes (where co-occurring species include grasses, sedges, and small willows), alpine wetlands (where co-occurring species include Salix brachycarpa, Salix glauca, Betula glandulosa, and mosses), moderately dry to moist alpine meadows, alpine cushion plant communities, and, occasionally, Engelmann spruce woodland to stunted krummholz. However, many sites (e.g. disturbed fell fields) are sparsely vegetated. 2850 - 4350 m.Distribution: Regional endemic of southwest Montana, northwest Wyoming, and central Colorado. Saussurea weberi is a rare plant species known from disjunct occurrences in alpine habitats across the middle Rocky Mountains, from central Colorado to southwestern Montana.

Ecological Relationships

Saussurea weberi is reportedly insect pollinated and an obligate out-crosser (Abbott 1998). Flowers in the Asteraceae are relatively small and individually play a relatively minor role in attracting pollinators. The functional pollination unit in the family is usually the head, composed of several to many flowers (Walters and Keil 1996)

Pollinators
Common Name Name in Text Association Type Source InteractionID
Bees
Bumble bees Bombus frigidus Confirmed Pollinator Link
Bumble bees Bombus sylvicola Suspected Pollinator Floral Link
Flies
Root-maggot flies Pegoplata Link
House flies and kin Thricops villicrura Confirmed Pollinator Link
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting

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