CPC National Collection Plant Profile

Astragalus hypoxylus

Photographer:
Lynda Pritchett-Kozak

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CPC National Collection Plant Profile

Astragalus hypoxylus


Family: 
Fabaceae  
Common Name: 
milkvetch
Author: 
S. Wats.
Growth Habit: 
Forb/herb
CPC Number: 
9549

Distribution
Protection
Conservation
References


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Astragalus hypoxylusenlarge
Photographer: Lynda Pritchett-Kozak

Astragalus hypoxylusenlarge
Photographer: Lynda Pritchett-Kozak


Astragalus hypoxylus is Not Sponsored
Primary custodian for this plant in the CPC National Collection of Endangered Plants is: 
Kathleen C. Rice contributed to this Plant Profile.

 
Astragalus hypoxylus


Plants are low herbaceous perennials, forming a rosette of branches that grow flat against the ground. The ends of the branches turn up a little, and the entire plant ranges from 10 cm in diameter in the wild, up to 30 cm wide in cultivation. Leaves are alternate, compound with 9-13 leaflets, and appear folded along the midrib. Inflorescences are clover-like, a globose head about 1 cm in diameter, with whitish petals with pale purplish tips. (Levin 1987) Fruits are small flat pods with 2-4 seeds, and are indehiscent (shed from the plant unopened). Fruits are partitioned into two separate halves by thin membranes, with the seeds enclosed in each half.

Astragalus hypoxylus is distinguished from other species of Astragalus by its rosette-forming growth habit and clover-like inflorescences. This species is so distinctive that and was originally classified in the genus Hamosa.

Distribution & Occurrence

State Range
  Arizona
State Range of  Astragalus hypoxylus
Habitat
  Plants are found in clearings in oak woodland comprised of Quercus hypoleucoides, Q. emoryi, Juniperus deppeana, and Pinus edulis. Exposures are generally south to southwest at 5300-5500 feet (USFWS 1996).

Distribution
  Plants were first described in 1882 from the type location in southern Arizona near the Mexico-U.S. border. The location description was not detailed, and plants were not seen again until 1986 in another mountain range (USFWS 1996) .

Number Left
  Three populations are known from the Huachuca Mountains in southern Arizona (USFWS 1996).

Protection

Global Rank:  
G1
 
1/20/1999
Guide to Global Ranks
Federal Status:  
SC
 
1/19/1996
Guide to Federal Status
Recovery Plan:  
No
 

State/Area Protection
  State/Area Rank Status Date  
  Arizona S1 8/1/2002  

Conservation, Ecology & Research

Ecological Relationships
  Unknown.

Threats
  Threats are attributed to trampling by humans and cattle. (Desert Botanical Garden 2000)

Current Research Summary
  Monitoring plots were established in 1988 and 1989 (Warren et al. 1989). Growth and reproductivity show a great deal of variance while seedling establishment and mortality are about equal (Warren et al. 1989). Desert Botanic Garden staff have noticed that a number of plants growing in disturbed areas along roadsides; shaded plants were larger that plants growing in full sun.

Current Management Summary
  Sites are closely stewarded by Coronado National Forest personnel. Monitoring has been done in the past, and is still being infrequently conducted (Warren et al. 1989, Gori et al. 1990).

Research Management Needs
  Relocation of parking lots along several Forest roads might prove beneficial to A. hypoxylus.

Ex Situ Needs
  Desert Botanical Garden collected seeds of Astragalus hypoxylus from both sites in 1991 and 1992. Two germination tests were conducted in 1992, yielding percentages of 66 and 76. These tests provided living plants to be used for research and production of additional seeds in cultivation.
In 1996, plants growing outdoors in a test area produced over 14,000 seeds which were hand-cleaned. This labor-intensive task took several months, involving separation of the two fruit halves, removal of the two septae enclosing each half, and extraction of the seeds which were approximately 2 mm across. The seeds are currently in frozen storage at -20C at Desert Botanical Garden and at the National Seed Storage Lab in Ft. Collins, Colorado.
Potentially the Garden has enough seeds now to attempt augmentations or re-introductions at more than one site.

References

Books (Single Authors)

Allen, O.N.; Allen, E.K. 1981. The Leguminosae: A source book of characteristics, uses and nodulation. Madison, WI: The Univ. of Wisconsin Press.

Barneby, R.C. 1964. Atlas of North American Astragalus. Bronx, New York: New York Botanical Garden. 1188p.

Kartesz, J.T. 1993. Species distribution data for vascular plants of 70 geographical areas, from unpublished data files at the North Carolina Botanical Garden.

Kartesz, J.T. 1996. Species distribution data at state and province level for vascular plant taxa of the United States, Canada, and Greenland (accepted records), from unpublished data files at the North Carolina Botanical Garden.

Kearney, T.H.; Peebles, R.H. 1973. Arizona flora. Berkeley, CA: University of California Press. 1085p.

Schmutz, E.M.; Freeman, B.N.; Reed, R.E. 1968. Livestock-poisoning plants of Arizona. Tucson, AZ: Univ. of Arizona Press.

Turner, N.J.; Szczaawinski, A.F. 1991. Common poisonous plants and mushrooms of North America. Portland, OR: Timber Press.

Warren, P.L.; Anderson, L.S.; Shafroth, P.B. 1989. Population studies of sensitive plants of the Huachuca and Patagonia Mountains, Arizona. Tucson, Arizona: The Nature Conservancy. 98p.

Books (Sections)

Frankel, O.H. 1983. Foreword. In: Schoenwald-Cox, C.M., editor. Genetics and conservation: a reference for managing wild animal and plant populations. The Benjamin/Cummings Publishing Co. Menlo Park, CA.

Karron, J.D. 1991. Patterns of genetic variation and breeding systems in rare plant species. In: Falk, D.A.; Holsinger, K.E., editors. Conservation of rare plants: Biology and genetics. Oxford University Press. Oxford, U.K.

Kartesz, J.T. 1999. A synonymized checklist of the vascular flora of the U.S., Canada, and Greenland. In: Kartesz, J.T.; Meacham, C.A., editors. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden. Chapel Hill, NC.

Electronic Sources

(2000). Center for Plant Conservation's National Living Collection--Profiles. Desert Botanical Garden. http://www.dbg.org/Collections/cpc.html. Accessed: 2002.

Arizona Game and Fish Department. (1999). Plant Abstracts. Compiled and edited by the Heritage Data Management System, Arizona Game and Fish Department, Phoenix, AZ. http://www.gf.state.az.us/frames/fishwild/hdms_site/Abstracts/Plants/abstracts%20-%20plants.htm. Accessed: 2002.

Journal Articles

Karron, J.D. 1987. A comparison of levels of genetic polymorphism and self-compatibility in geographically restricted and widespread plant cogeners. Evolutionary Ecology. 1: 47-58.

Karron, J.D. 1989. Breeding systems and levels of inbreeding depression in geographically restricted and widespread species of Astragalus (Fabaceae). American Journal of Botany. 76, 3: 331-340.

Karron, J.D.; Linhart, Y.B.; Chaulk, C.A.; Robertson, C.A. 1988. Genetic structure of populations of geographically restricted and widespread species of Astragulus (Fabaceae). American Journal of Botany. 75, 8: 1114-1119.

Levin, G.A. 1987. Noteworthy collections: Astragalus hypoxylus S. Wats. (Fabaceae). Madroņo. 34, 2: 170.

Spellenberg, R. 1986. Chromosome numbers and their cytotaxonomic significance for North American Astragalus (Fabaceae). Taxon. 25: 463-476.

USFWS. 1996. Endangered and Threatened Wildlife and Plants: Review of Plant Taxa that are Candidates for Listing as Endangered or Threatened Species: Notice of Review. Proposed Rule. Federal Register. 61, 40: 7595-7613.

Williams, M.C.; Barneby, R.C. 1977. The Occurrence of Nitro-toxins in North America Astragalus (Fabaceae). Brittonia. 29, 3: 310--326.

Reports

Gori, D.; Malasa, J.; Warren, P.L.; Monarqui, E.S. 1991. Population studies of sensitive plants of the Huachuca, Patogonia and Atascusa Mountains, Arizona. Tuscon, Arizona: The Arizona Nature Conservancy.

Gori, D.F.; Warren, P.L.; Anderson, L.S. 1990. Population studies of sensitive plants of the Huachuca, Patagonia and Atacosa Mountains, Arizona. Tucson, AZ: Prepared by The Arizona Nature Conservancy and Submitted to Coronado National Forest in completion of P.O. No. 40-8197-0-0215.

Warren, P.L.; Gori, D.F.; Gebow, B.; Malusa, J. 1991. Status report: Astragalus hypoxylus Watson. Tucson, AZ: The Arizona Nature Conservancy.


  This profile was updated on 3/4/2010
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