CPC Plant Profile: Tharp's Bluestar
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Plant Profile

Tharp's Bluestar (Amsonia tharpii)

Amsonia tharpii in habitat. Stems branch from a thich woody root stock at the base of the plant and grow less than 30 cm tall. Photo Credit: Kathy Rice
Description
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: N/A
  • Family: Apocynaceae
  • State: NM, TX
  • Nature Serve ID: 141086
  • Date Inducted in National Collection: 04/04/1991

Plants are herbaceous perennials from a long woody taproot. They become dormant, dying back to the ground during November and emerging from dormancy during March. Leaves are sessile, linear-lanceolate with rounded tips, about 3 cm long and whorled on stems. Flowers are white, clustered at ends of stems, and are followed by two-lobed follicles. As follicles mature, they open completely, becoming flat and papery, dispersing all of the seeds inside except perhaps one remaining at the base of the follicle tube. Seeds are corky and cylindrical, about 1 cm long, and are irregularly truncated at the ends.

Participating Institutions
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Updates
Center for Plant Conservation
  • 08/17/2021
  • Orthodox Seed Banking

In 2021, CPC contracted the Desert 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.

  • 08/18/2020
  • Reproductive Research

Desert Botanical Garden has 600 seeds from the Texas population, and 959 seeds from the New Mexico population. Thirty-three plants grown from seed obtained in Texas have been maintained in pots beneath 30% shade for approximately 10 years. During this time, only seven seeds were produced in cultivation through hand-pollination efforts. Flowering is in April, but not always reliable on a yearly basis, even under controlled conditions in cultivation. Plans for A. tharpii include continuation of seed collection when conditions permit, and further attempts to produce seeds in cultivation.

  • 08/18/2020
  • Living Collection

Desert Botanical Garden has 600 seeds from the Texas population, and 959 seeds from the New Mexico population. Thirty-three plants grown from seed obtained in Texas have been maintained in pots beneath 30% shade for approximately 10 years. During this time, only seven seeds were produced in cultivation through hand-pollination efforts. Flowering is in April, but not always reliable on a yearly basis, even under controlled conditions in cultivation. Plans for A. tharpii include continuation of seed collection when conditions permit, and further attempts to produce seeds in cultivation

  • 08/18/2020
  • Orthodox Seed Banking

Desert Botanical Garden has 600 seeds from the Texas population, and 959 seeds from the New Mexico population. Thirty-three plants grown from seed obtained in Texas have been maintained in pots beneath 30% shade for approximately 10 years. During this time, only seven seeds were produced in cultivation through hand-pollination efforts. Flowering is in April, but not always reliable on a yearly basis, even under controlled conditions in cultivation. Plans for A. tharpii include continuation of seed collection when conditions permit, and further attempts to produce seeds in cultivation.

  • 08/18/2020
  • Seed Collection

Desert Botanical Garden has 600 seeds from the Texas population, and 959 seeds from the New Mexico population. Thirty-three plants grown from seed obtained in Texas have been maintained in pots beneath 30% shade for approximately 10 years. During this time, only seven seeds were produced in cultivation through hand-pollination efforts. Flowering is in April, but not always reliable on a yearly basis, even under controlled conditions in cultivation. Plans for A. tharpii include continuation of seed collection when conditions permit, and further attempts to produce seeds in cultivation.

Nature Serve Biotics
  • 05/02/2017

There are only 3 populations in New Mexico and only 1 site is known in Texas. The Texas and New Mexico sites are over 160 km apart. Threats include gas well development and environmental changes brought about by past overgrazing including erosion and increased competition with non-native species (Desert Botanical Garden 2000).

Kathleen C. Rice
  • 01/01/2010

The area surrounding the canyon where A. tharpii grows in New Mexico appears to have been overgrazed for some time (New Mexico Conservancy 1989). Many trenches, some as deep as five feet and two to three feet wide, have been eroded into the southwest sid

Kathleen C. Rice
  • 01/01/2010

Three populations of this species are known from New Mexico, and possibly one in Texas. Two of the populations in New Mexico are relatively large (over one thousand individuals each), while the third contains fewer than 100 individuals. (New Mexico Rare Plant Technical Council 1999)

Kathleen C. Rice
  • 01/01/2010

None known.

Kathleen C. Rice
  • 01/01/2010

Management is different for the two sites, but the ultimate result may be the same. At the Bureau of Land Management, New Mexico managed site near Carlsbad, plants are merely checked every year. This may or may not be beneficial, as the soil at that site is extremely friable, almost powdery and fluffy and may becoming more erosive with each subsequent visit (New Mexico Conservancy 1989). At the Texas site, plants are rarely checked, but they are fenced off from a large empty, rocky pasture. There appears to be a larger number of small-sized plants at this site than at the Carlsbad site.

Kathleen C. Rice
  • 01/01/2010

Investigation into reproductive biology is needed, and molecular work to determine diversity within the New Mexico population. Size- and age-class data on these plants is needed, from germination to reproductive maturity, as the size of plants in the wild is primarily resource-dependent.

Kathleen C. Rice
  • 01/01/2010

Desert Botanical Garden has 600 seeds from the Texas population, and 959 seeds from the New Mexico population. Thirty-three plants grown from seed obtained in Texas have been maintained in pots beneath 30% shade for approximately 10 years. During this time, only seven seeds were produced in cultivation through hand-pollination efforts. Flowering is in April, but not always reliable on a yearly basis, even under controlled conditions in cultivation. Plans for A. tharpii include continuation of seed collection when conditions permit, and further attempts to produce seeds in cultivation.

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Photos
Nomenclature
Taxon Amsonia tharpii
Authority Woodson
Family Apocynaceae
CPC Number 125
ITIS 30149
USDA AMTH
Common Names Tharp's blue-star | feltleaf bluestar
Associated Scientific Names Amsonia tharpii
Distribution Two very disjunct locations exist within U.S. boundaries--in Pecos County, Texas, and Eddy County, New Mexico. Both are relatively close to the Pecos River, and it could be imagined that this river w
State Rank
State State Rank
New Mexico S1
Texas S1
Habitat

Found in the limestone and gypsum hills of the Chihuahuan desert scrub communities at elevations of 900 to 1,150 meters (3,100 to 3,500 feet). (New Mexico Rare Plant Technical Council 1999)

Ecological Relationships

Plants contain a milky sap that makes them unpalatable to cattle. (USFWS 1990)

Pollinators
Common Name Name in Text Association Type Source InteractionID
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting

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