CPC National Collection Plant Profile

Pilosocereus robinii

Photographer:
Lippincott

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CPC National Collection Plant Profile

Pilosocereus robinii


Family: 
Cactaceae  
Common Names: 
Key tree cactus, Keys tree cactus
Author: 
(Lemaire) Byles and Rowley
Growth Habit: 
Tree
CPC Number: 
15862

Distribution
Protection
Conservation
References


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Pilosocereus robiniienlarge
Photographer: Lippincott

Pilosocereus robiniienlarge
Photographer: Daniel F. Austin
Image Owner: Smithsonian


Pilosocereus robinii is Not Sponsored
Primary custodian for this plant in the CPC National Collection of Endangered Plants is: 
Jennifer Possley contributed to this Plant Profile.

 
Pilosocereus robinii


The keys tree cactus is unlike any other plant in Florida. It is a true tree, with mature individuals possessing differentiated trunks and branches (Avery 1982). Plants can reach as high as 10 m, and may have dozens of spreading branches (Ward 1979), though most of the larger plants have been destroyed by development and hurricanes (USFWS 1986). The showy, 6 cm-long flowers are reported to smell like garlic (Hennesey and Habeck 1994). Although first discovered in the early 1800s, this species was very little studied until 75 years later (Small 1917), due in part to both its isolation from civilization and the awkwardness of making herbarium specimens of such a large cactus.

Distribution & Occurrence

State Range
  Florida
State Range of  Pilosocereus robinii
Habitat
  Rocky tropical hardwood hammocks (USFWS 1986)

Distribution
  The Florida Keys and Cuba (USFWS 1986).

Number Left
  Populations: 9 in Florida (FNAI 1998), 1 unconfirmed in Cuba (Adams, undated report)

Individuals: 624 in the Keys (Adams and Lima 1994), and an unknown number in Cuba

Protection

Global Rank:  
G1
 
6/17/1997
Guide to Global Ranks
Federal Status:  
LE
 
Guide to Federal Status
Recovery Plan:  
No
 

State/Area Protection
  State/Area Rank Status Date  
  Florida S1 LE  

Conservation, Ecology & Research

Ecological Relationships
  Pollinators are unknown, but Adams and Lima (1994) theorize it must be a sphingid moth, since no other insects capable of pollinating the large flowers were seen at the site, and no nectar feeding bats are native to the Keys.

Threats
  Known threats include habitat destruction and hurricanes (the latter of which limit size, but probably not reproduction) (USFWS 1986).

Other possible threats include canopy closure, salt water intrusion, drainage, competition, and accumulation of soil organic matter (USFWS 1986).

Current Research Summary
  Reproduction: The Keys tree cactus flowers year round, peaking in July, August and September. Flowers bloom (and smell garlicky) at night (Hennessey and Habeck 1994). Seed viability was 57.7% (N=6397) and fruit set was 21.9% (N=32) in laboratory trials (Adams, undated report).

Natural History: Information on population age class, growth rates, and architecture is contained in Adams and Lima (1994). Dr. Peter Stiling, of the University of South Florida, may be continuing natural history research.

Predation: Adams and Lima (1994) noted ants and cardinals predating on the seeds and fruit, respectively.
Hennessey, M. K. and D. H. Habeck (1994). "Observations on reproduction of an endangered cactus, Cereus robinii (Lemaire) L. Benson." Florida Scientist 57: 93-101.
This rare cactus is subjected to mosquito insecticide spraying which has an unknown effect on its pollinators. No pollinators were observed, so cross pollination by animals remains unconfirmed. Its floral biology strongly suggests pollination by bats or moths. Pesticide spraying could have impacts on its reproductive cycle.

Current Management Summary
  Responsible Agencies: Florida Department of Environmental Protection, Florida Keys National Wildlife Refuge, U.S. Fish and Wildlife Service, private landowners.

The National Wildlife Refuge and USFWS protect the land containing the largest population of the Keys tree cactus, but they do not regularly monitor the population. FDEP conducts periodic monitoring of the populations on its lands.

Research Management Needs
  A regular monitoring schedule on Federal lands.

A clear summary of the status of the Keys tree cactus on private lands.

Outplanting of the cactus onto sites where it currently or historically is/was found.

Research on the effects of light levels, salt water, organic matter or competition.

Ex Situ Needs
  It has not been determined with certainty whether the two apparent forms of the Keys tree cactus are genetically nondistinct.

If an outplanting were to take place, seeds need to be collected and used to propagate seedlings for outplanting.

References

Books (Single Authors)

Coile, N.C. 2000. Notes on Florida's Regulated Plant Index (Rule 5B-40), Botany Contribution 38. Gainesville, Florida: Florida Dept. of Agriculture and Consumer Services, Division of Plant Industry.

FNAI. 2000. Field Guide to the Rare Plants and Animals of Florida online. Florida Natural Areas Inventory.

Electronic Sources

(2002). Atlas of Florida Vascular Plants. [Web site] University of South Florida Institute for Systematic Botany. http://www.plantatlas.usf.edu/isb/default.htm. Accessed: 2008.

Journal Articles

Hennessey, M.K.; Habeck, D.H. 1994. Observations on reproduction of an endangered cactus, Cereus robinii (Lemaire) L. Benson. Florida Scientist. 57: 93-101.

Kartesz, J.T.; Gandhi, K.N. 1991. Nomenclatural notes for the North American Flora VIII. Phytologia. 71, 4: 269-280.

Lippincott, C. 1990. Rare Plant Conservation. Fairchild Tropical Garden Bulletin. 6-15.

USFWS. 1984. Protection. Endangered Species Technical Bulletin. 9, 8: 3-6.

Reports

Adams, R.M.; Lima, A.N. 1994. The natural history of the Florida keys tree cactus, Pilosocereus robinii. Jacksonville, FL: U.S. Fish and Wildlife Service.

Adams, Ralph M. Not dated. The Sexual Reproductive Potential of the Florida Keys Tree-Cactus, Pilosocereus robinii. Tallahassee, Florida: Florida Division of Forestry: Statewide Endangered and Threatened Plant Conservation Program.

Avery, G.N. 1982. Cereus robinii in Florida. Tallahassee, Florida: Florida Natural Areas Inventory.

USFWS. 1999. South Florida Multi-species Recovery Plan. Atlanta, GA: U.S. Fish and Wildlife Service, Southeast Region.


  This profile was updated on 3/4/2010
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