CPC Plant Profile: Ruth's Silk-grass
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Plant Profile

Ruth's Silk-grass (Pityopsis ruthii)

This shot shows a mass of Ruth's golden aster flowers. Photo Credit: Rob Gardner
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: Federally Endangered
  • Family: Asteraceae
  • State: TN
  • Nature Serve ID: 153865
  • Date Inducted in National Collection: 04/04/1991

Ruth's Golden-aster is an herbaceous tufted perennial that has slender stoloniferous rhizomes. Its leaves are numerous, cauline, linear, and silvered with long apressed hairs. The inflorescence is comprised of one to several heads of yellow composite flowers in a cyme. This southeastern Tennessee endemic has only two known populations. Ruths golden-aster grows in the crevices of boulders in the natural flood zone of the Hiwassee and Ocoee Rivers, where upstream activities have significantly altered the riparian habitat. Threats include disruption of natural flooding cycles by dam construction, degradation of water quality by mining activity, toxic chemical spills, and trampling by recreational boaters. Ruths golden-aster populations have historically been maintained on these riverbanks due to periodic high water flows that remove competing vegetation. On the Hiwassee River, the prevention of flooding has caused increased competition and invasion by shade-tolerant species. On the Ocoee River, the increased frequency and decreased magnitude of flooding events (water releases for hydropower and recreational activities) has prevented recruitment of new plants. The protection and recovery of Pityopsis ruthii is currently overseen jointly by a number of organizations.

Participating Institutions
Center for Plant Conservation
  • 08/19/2021
  • Orthodox Seed Banking

In 2021, CPC contracted North Carolina Botanical Garden to recollect seed from a population currently held in long term orthodox seed storage as part of an IMLS-funded seed longevity experiment. The National Laboratory for Genetic Resources Preservation will evaluate how germination tested viability and RNA Integrity of seed lots decline over time in storage.

Nature Serve Biotics
  • 05/02/2017

A very localized endemic of southeastern Tennessee. The only two populations known are on short reaches of rivers which have been dammed, essentially eliminating natural water flows. On one of the rivers, annual scouring no longer occurs and shade-tolerant species are rapidly invading and replacing Pityopsis ruthii. On the other, whitewater recreation related impacts are a threat.

  • 01/01/2010

Succession/competition (Hiwassee population) Construction and repair of highways Competition from woody and herbaceous plants Water quality degradation Alterations in water levels and flow regimes Toxic chemical spills Trampling (due

  • 01/01/2010

Known from 2 populations in Polk Co., TN: Ocoee River with exactly 593 individuals, and Hiwassee with ca. 10,000-15,000 individuals (USFWS 1992)

  • 01/01/2010

M.B. Cruzan at the University of Tennessee at Knoxville studied the long-term demographic trends in Pityopsis ruthii. (Cruzan 1996)

  • 01/01/2010

None known.

  • 01/01/2010

Surveys for additional occurrences on other rivers in TN and in southwestern NC Re-introduction research Continuing protection of populations from trampling Plans for mitigating effects of dams and mining activities Pollination studies Fruit dispersal and recruitment of seedlings

  • 01/01/2010

Further seed collection from Ocoee River population.

Jennifer Ceska 05/02/2019

Our team is working on the reintroduction of a species endemic to cracks in rocks of shoals. The water does eb and flow but stays generally wet. Has anyone tried glues to help plants establish within rocks? Our current collection is robust, has a large root mass grown in beds compared to in situ material that is essentially "bonsai-grown" in small rock cracks. We will re-grow this material to establish at younger, smaller size. But is there a glue or some sort of material that can help the plant material "stick" or "puddy-in" to the rock? 

Taxon Pityopsis ruthii
Authority (Small) Small
Family Asteraceae
CPC Number 3492
ITIS 196342
Common Names Ruth's golden-aster | Ruth's goldaster
Associated Scientific Names Pityopsis ruthii | Heterotheca ruthii | Chrysopsis ruthii
Distribution Polk County, Tennessee (USFWS 1992)
State Rank
State State Rank
Tennessee S1

Found in soil-filled cracks of phyllite or graywacke boulders in riparian areas/rocky river shoals which experience periodic flooding and scouring. (USFWS 1992)

Ecological Relationships

Strongly associated with Liatris microcephala (USFWS 1992). White (1977) has suggested that since Pityopsis requires at least 50 percent of full sunlight, it is often unable to compete with its taller, more vigorous associates (e.g., Aster dumosus and Solidago arguta ssp. caroliniana) Although the current habitat is restricted to cracks in phyllite boulders, analyses have not indicated that the presence of any particular nutrients, minerals or chemicals found in soil or surrounding rock is required for survival of Pityopsis ruthii. The crucial factor appears to be exposure to sunlight (USFWS 1992). Rocky river shoals which experience periodic flooding and scouring are required to remove competing vegetation, since the species is shade intolerant.

Common Name Name in Text Association Type Source InteractionID
Bumble bees Bombus impatiens Confirmed Pollinator Link
Honey bees Apis mellifera Confirmed Pollinator Link
Syrphid flies Toxomerus geminatus Suspected Pollinator Floral Link

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