CPC Plant Profile: Huachuca Milkvetch
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Plant Profile

Huachuca Milkvetch (Astragalus hypoxylus)

Astragalus hypoxylus is found in stony openins in pine-oak-juniper woodland on limestone-derived soil. Photo Credit: Lynda Pritchett-Kozak
Description
  • Global Rank: N/A
  • Legal Status: N/A
  • Family: Fabaceae
  • State: AZ
  • Nature Serve ID: 130953
  • Date Inducted in National Collection: 04/04/1991

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.

Participating Institutions
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.

  • 08/27/2020
  • Orthodox Seed Banking

The seeds are currently in frozen storage at -20C at Desert Botanical Garden and at the National Seed Storage Lab in Ft. Collins, Colorado.

  • 08/27/2020
  • Propagation Research

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.

  • 08/27/2020
  • Orthodox Seed Banking

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.

  • 08/27/2020
  • Seed Collection

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.

Nature Serve Biotics
  • 05/02/2017

This species' known range is restricted to the Patagonia and Huachuca Mountains in extreme southeastern Arizona, and three locations in Yecora, Sonora Mexico. Five populations are known, one of which is in an area that is known to receive heavy recreational use.

Kathleen C. Rice
  • 01/01/2010

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

Kathleen C. Rice
  • 01/01/2010

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

Kathleen C. Rice
  • 01/01/2010

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.

Kathleen C. Rice
  • 01/01/2010

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).

Kathleen C. Rice
  • 01/01/2010

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

Kathleen C. Rice
  • 01/01/2010

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.

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Photos
Nomenclature
Taxon Astragalus hypoxylus
Authority S. Wats.
Family Fabaceae
CPC Number 9549
ITIS 25542
USDA ASHY3
Common Names milkvetch | Huachuca Mountain milkvetch | Huachuca milk-vetch
Associated Scientific Names Astragalus hypoxylus | Hamosa hypoxyla
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 anot
State Rank
State State Rank
Arizona S1
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).

Ecological Relationships

Unknown.

Pollinators
Common Name Name in Text Association Type Source InteractionID

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