Amsonia tharpii (Tharp's Blue Star)

Amsonia tharpii (Tharp's Blue Star)

Photograph by Robert Sivinski (2010)
Family
APOCYNACEAE
Scientific Name with Author

Amsonia tharpii Woodson

Synonyms

NONE

Common Name
Tharp's Blue Star
Rare Plant Conservation Scorecard Summary
Overall Conservation Status Documented Threats Actions Needed
WEAKLY CONSERVED

Oil & gas development, herbicide treatments

seed banking by Desert Botanic Garden (need to send some to National Germplasm System)


County Map
Counties
Description

Perennial suffrutescent herb; stems from a woody rootstock, up to 2 dm tall; leaves subsessile, crowded, up to 5 cm long and 12 mm wide, those on the lower half of the stem elliptic-lanceolate and those above linear to linear-lanceolate; flowers pale-blue or greenish-white, salverform, the tube about 15 mm long and constricted at orifice; fruit two short, thick follicles, glabrous, 25-35 mm long. Flowers April to May.

Similar Species

Tharp's blue-star is the only Amsonia in this region with dimorphic leaves. Amsonia longiflora is sympatric but distinguished by its narrow lower stem leaves and longer (25-45 mm) fragrant flowers.

Distribution

New Mexico, Eddy County; Texas, Pecos County.

Habitat

Limestone and gypsum hills in Chihuahuan desert scrub communities; 900-1,150 m (3,100-3,500 ft).

Remarks

Only four populations of this plant are presently known in New Mexico.

Conservation Considerations

There is active gas development in the vicinity of two of the New Mexico populations. Extensive surveys in 2012 & 2013 documented only 2 additional sites.

Important Literature

Correll, D.S., M.C. Johnston and collaborators. 1979. Manual of the vascular plants of Texas (2nd printing). Texas Research Foundation, Renner (2nd printing by University of Texas at Dallas, Richardson).

McLaughlin, S.P. 1982. A revision of the southwestern species of Amsonia (Apocynaceae). Annals of the Missouri Botanical Garden 69:336-350.

Roth, D. 2013. Status report Amsonia tharpii (Tharp's bluestar) on NM State Trust Lands (Section 6, Segment 27). Unpublished report prepared by the Energy, Minerals, and Natural Resources Department, Forestry Division, for the U.S. Fish & Wildlife Service, Region 2, Albuquerque, NM.

Roth, D. and R. Sivinski.  2019. Status survey and report.  Tharp's bluestar (Amsonia tharpii). Unpublished report prepared by the Energy, Minerals, and Natural Resources Department, Forestry Division, for the U.S. Fish & Wildlife Service, Region 2, Albuquerque, NM.  

Natural Heritage New Mexico. 2014. Status survey for Tharp's bluestar in the Carlsbad, New Mexico area. Final Report. Natural Heritage New Mexico report 14-GTR-384.

Information Compiled By
Ken Heil, Joey Herring 1999. Updated 2020.

For distribution maps and more information, visit Natural Heritage New Mexico