CPC National Collection Plant Profile

Mammillaria thornberi

Photographer:
Lynda Pritchett-Kozak

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CPC National Collection Plant Profile

Mammillaria thornberi


Family: 
Cactaceae  
Common Name: 
Thornber's fishhook cactus
Author: 
Orcutt
Growth Habit: 
Shrub
CPC Number: 
2795

Distribution
Protection
Conservation
References


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Mammillaria thornberienlarge
Photographer: Lynda Pritchett-Kozak


Mammillaria thornberi 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.

 
Mammillaria thornberi


Mamillaria thornberi is a small, clumping columnar cactus with a soft body and numerous tubercules without dorsal grooves (as in Coryphantha). The stems are approximately 15 cm high, and ca 2 cm in diameter. Each tubercule has 10-20 straw-colored radial spines, and a single darker large hooked central spine-hence the name 'fishook cactus' (Benson 1982). Pinkish-white flowers bloom sporadically, usually following heavy rains. Flowers form in a ring around the upper portion of the stem, but not at the apex. The edible fruits are bright red, fleshy, ca. 2 cm long, and shaped like little chili-peppers.

Species in the genus Mammillaria often go through "boom and bust" population cycles. This species is a good example of that, as it occurred in the millions in the Avra Valley west of Tucson in the 1930's, but most of the population disappeared in a catastrophic freeze in 1937. The population never recovered, and the species was considered for federal threatened status in the mid-1980's.

Distribution & Occurrence

State Range
  Arizona
State Range of  Mammillaria thornberi
Habitat
  The microhabitat preferred by M. thornberi is the area beneath the overhanging side branches of Ambrosia dumosa (Rutman 1995). In order to find plants, one must lift these branches up to inspect the area beneath each Ambrosia plant, an onerous task as Ambrosia dumosa is highly abundant in southern Arizona.

Distribution
  South-central Arizona

Number Left
  There are eight major populations, with only 2 sites on protected lands. The majority of other populations are found on the Tohono O'odham, and the San Xavier reservations, and on private land (Rutman 1995).

Protection

Global Rank:  
G4
 
5/13/1999
Guide to Global Ranks
Federal Status:  
RT
 
7/27/1987
Guide to Federal Status
Recovery Plan:  
No
 

State/Area Protection
  State/Area Rank Status Date  
  Arizona S4 8/1/2002  
  Mexico *FR83 8/26/1988  
  Sonora S3 8/28/1991  

Conservation, Ecology & Research

Ecological Relationships
  Relationships between root systems of M. thornberi and the mycorrhizal community has been investigated. A relationship indeed exists, but it's exact nature requires further study.

Threats
  Threats to M. thornberi include urban development and maintenance of the Central Arizona Project Canal (Nabhan et al. 1986).

Current Research Summary
  Desert Botanical Garden has 110 accessioned plants which were salvaged from an area slated as right-of-way for the Central Arizona Project Canal, and 42 clones of the accessioned plants. Additionally the Garden has at least 250,000 seeds produced in cultivation. Plants are prolific seed producers, fruiting as frequently as they flower. Initial tests on seed that had been processed and frozen yielded percentages of approximately 30%, but tests conducted on desiccated seed stored at room temperature for 2 years resulted in 75% germination. Germination tests are in progress on seeds stored using a variety of storage methods.

Current Management Summary
 

Research Management Needs
  Habitat protection would aid in conserving this species. Understanding the impact of Ambrosia dumosa on the population dynamics of Mammillaria thornberi would be useful as would knowing this species general reproductive biology and ecology.

Ex Situ Needs
 

References

Books (Single Authors)

Benson, L. 1982. The Cacti of the United States and Canada. Stanford, California: Stanford University Press. 1044p.

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.

Books (Sections)

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.

Journal Articles

1984. Endangered Species. AABGA Newsletter. pp. 5.

Nabhan, G.; Gass, V.; Quirk, P. 1986. Thornber's Fishook Cactus: conserving a declining species. Agave. 2, 2: 4-8.

Thomas, P.A.; Goodson, P. 1992. Conservation of succulents in desert grasslands managed by fire. Biological Conservation. 60, 2: 91-100.

USFWS. 1984. Carex specuicola. Endangered Species Technical Bulletin. 9, 5: 11.

USFWS. 1984. Four Western Plants. Endangered Species Technical Bulletin. 9, 5: 8-9.

USFWS. 1984. Proposal to Determine Mammillaria thornberi (Thornber's Fishhook Cactus) to be a Threatened Species. Federal Register. 49, 80: 17551-17553.

USFWS. 1985. Notice of Six-Month Extension on the Proposed Rule for Mammillaria thornberi (Thornber's Fishhook Cactus). Federal Register. 50, 111: 24241-24242.

USFWS. 1988. Regional News--Region 2. Endangered Species Technical Bulletin. 13, 11-12: 3.

Reports

McLaughlin, S. 1987. Salvage, propagation and re-establishment of Mamillaria thornberi. Tucson, Arizona: Progress report: Tucson Water.

McLaughlin, S. 1988. Salvage, propagation and re-establishment of Mamillaria thornberi. Tucson, Arizona: Progress report: Tucson Water.

Rutman, S. 1995. The distribution of Mamillaria thornberi on Saguaro National Monument, Tucson Mountain Unit, Arizona. Tucson, Arizona: Saguaro National Monument.

Theses

Ecker, Liz S. 1990. Population enhancement of a rare Arizona cactus, Mammillaria thornberi Orcutt (Cactaceae). [M.S. Thesis]: Arizona State University. 95p.


  This profile was updated on 3/4/2010
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