Dendrosicyos socotrana 


Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Cucurbitales Cucurbitaceae

Scientific Name: Dendrosicyos socotrana
Species Authority: Balf. f.
Common Name(s):
English Cucumber Tree

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2cd ver 3.1
Year Published: 2004
Date Assessed: 2004-04-30
Needs updating
Assessor(s): Miller, A.
Reviewer(s): Abuzinada, A.H. & AL-Eisawi, D.M.H. (Arabian Plants Red List Authority)
At present, the main threats to this flagship species are its use as a drought fodder. In the main, with its swollen, water-storing stem it is well adapted to withstand drought conditions and should therefore be better able than many species to tolerate any drying out of the Archipelago due to climate change. However, in times of severe drought trees are cut-down, pulped and fed to livestock. In some areas (Kilissan) this has resulted in its almost total eradication. Change of habitat is also an important factor in preventing regeneration. Typically, on the plains, seedlings germinate and grow, protected from livestock, in the cover of dense vegetation such as provided by the spiny shrub Lycium sokotranum or by colonies of the succulent shrub Cissus subaphylla. So where there is no Cissus or Lycium there is little, if any, regeneration. Thus, along the southern region of Soqotra and on Samha the recovery of populations of Dendrosicyos after drought is dependant on the presence of colonies of Cissus. Dendrosicyos socotranum is considered vulnerable to extinction due to the decline in quality of its habitat (due to drought) in certain areas and, the level of exploitation of populations already stressed by drought.
Previously published Red List assessments:
1998 Vulnerable (V)
1998 Vulnerable (VU)
1978 Vulnerable (V)

Geographic Range [top]

Range Description:Endemic to Soqotra.
Countries occurrence:
Yemen (Socotra)
Range Map:Click here to open the map viewer and explore range.

Population [top]

Current Population Trend:Unknown
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Widespread in dry areas on Soqotra; locally common in Croton socotranus shrubland on the plains and locally abundant in succulent shrubland on limestone; less common on igneous rocks; rare on Samha. Altitude of sea-level to 500 m.

Dendrosicyos socotranus is a monotypic, endemic genus, and perhaps the best example of the swollen-trunked bottle-trees for which Soqotra is famous. On Soqotra it is widely distributed in several vegetation types but has a rather fragmented distribution; over large areas there are only isolated trees or small, relict populations, whilst in other ares it is relatively abundant. There are a few trees on the island of Samha, but none on Darsa or Abd al-Kuri.

Threats [top]

Major Threat(s): The whole plant is cut and pulped for livestock fodder. Although current levels of use are sustainable, there is a potential risk of increasing livestock numbers placing populations under severe pressure.

Classifications [top]

3. Shrubland -> 3.5. Shrubland - Subtropical/Tropical Dry
suitability: Suitable  
0. Root -> 6. Rocky areas (eg. inland cliffs, mountain peaks)
suitability: Suitable  

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
In-Place Species Management
In-Place Education
2. Agriculture & aquaculture -> 2.3. Livestock farming & ranching -> 2.3.4. Scale Unknown/Unrecorded
♦ timing: Ongoing    
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

5. Biological resource use -> 5.3. Logging & wood harvesting -> 5.3.1. Intentional use: (subsistence/small scale)
♦ timing: Ongoing    
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

11. Climate change & severe weather -> 11.2. Droughts
♦ timing: Ongoing    
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation
  • 2. Species Stresses -> 2.2. Species disturbance
  • 2. Species Stresses -> 2.3. Indirect species effects -> 2.3.8. Other

Bibliography [top]

IUCN. 2004. 2004 IUCN Red List of Threatened Species. Downloaded on 23 November 2004.

Lucas, G.L.l. and Synge, H. (compilers). 1978. The IUCN Plant Red Data Book. IUCN, Morges, Switzerland.

Miller, A.G. 1992. List of Socotran endemics with conservation status. Revised November 1991 (unpublished).

Miller, A.G. 1997. Completed data collection forms and comments concerning the threatened trees of Socotra and Yemen.

Oldfield, S., Lusty, C. and MacKinven, A. (compilers). 1998. The World List of Threatened Trees. World Conservation Press, Cambridge, UK.

Citation: Miller, A. 2004. Dendrosicyos socotrana. In: The IUCN Red List of Threatened Species 2004: e.T33691A9797777. . Downloaded on 25 May 2016.
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