Quiver tree (Aloe dichotoma)

Description

Quiver tree fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Quiver tree description

The quiver tree (Aloe dichotoma) is a distinctive member of a group of succulent plants known as ‘Aloes’ that grows to tree-like proportions ⁽⁵⁾. It is perhaps one of the best known desert plants in southern Africa, and arguably the most striking floral species in its native landscape. As a result of its beauty, the quiver tree has been named the national plant of Namibia ⁽⁶⁾. 

The quiver tree has a stout stem that may grow to one metre in diameter, and is covered in a thick, corky, yellowish bark that flakes into sharp-edged sections on the main trunk. The branches are smooth and are covered with a thin layer of whitish powder that helps to reflect the sun’s rays ^{(2) (5) (7)}. 

The quiver tree does not have real ‘wood’, instead having a much softer pulpy, fibrous tissue in the trunk and branches. Typically, the trunk tapers from a thick base towards the top, with the first branches appearing about halfway up. The crown is often densely rounded as a result of the repeatedly forked branches, hence the species name ‘dichotoma’, which means forked. The blue-green leaves are borne on rosettes at the end of the branches, but in juvenile plants the leaves are arranged in vertical rows. Short, erect inflorescences arise from amidst the rosettes. The inflorescences branch into three to five racemes, which bear the short, rounded, yellow flowers ^{(2) (5) (7) (8)}. 

The name ‘quiver tree’ comes from the habit of the San people, or Bushmen, who use the branches of this species for making quivers to contain their poison arrows. This plant also has other uses, and the large trunks of dead trees may be hollowed out and used as a natural fridge. The fibrous tissue of the trunk has a cooling effect as air passes through it, and water, meat and vegetables are stored inside ⁽⁵⁾. Other reported uses include the use of the bark as building material, and the wood pulp as a source of drinking water ⁽⁶⁾. The young flower buds can also be eaten and are said to have a similar appearance and taste to asparagus ⁽⁵⁾.

Also known as

Kokerboom.

Synonyms

Aloe dichotoma montana, Aloe montana, Aloe ramosa, Rhipidodendrum dichotomum.

Size

Height: up to c. 9 metres ⁽²⁾

Quiver tree biology

The quiver tree holds tremendous ecological value within its native landscape. Bright yellow flowers are borne from June to July, when a huge variety of insects, birds and mammals are drawn to the abundant nectar. Sugarbirds lap at the nectar with their elongated tongues, while baboons climb into the plants and tear at the flowers to get to the nectar. The quiver tree is also an important nesting site for huge numbers of breeding sociable weavers (Philetarius socius). These gregarious birds build their communal haystack-like nests amongst the foliage, which offers the nestlings protection from high temperatures, as well as protection from predators. An entire flock of sociable weavers may nest in just a single quiver tree ⁽⁷⁾. The quiver tree may reach an age of over 80 years ⁽⁵⁾.

Quiver tree range

The quiver tree occurs only in South Africa and Namibia, where it is perhaps the best known Aloe species. In South Africa, it is distributed around the lower reaches of the Orange River, ranging from the region of Kuruman, westwards to where the river discharges into the Atlantic Ocean. In the western part of the Northern Cape Province it ranges southwards into the Namaqualand. The quiver tree is widely distributed in Namibia, ranging from the Orange River, northwards to the Etosha Pan ⁽⁷⁾.

Quiver tree habitat

The quiver tree occurs in desert and semi-desert areas, where it grows in rocky areas. It can also be found in wetter parts of South Africa, such as the western Cape, where it requires adequate drainage to survive. The quiver tree is also frequently grown in gardens ^{(5) (7)}.

Quiver tree status

The quiver tree is classified as Vulnerable (VU) on the Interim Red Data List of South African Plant Taxa ⁽³⁾ and listed on Appendix II of CITES ⁽⁴⁾.

Quiver tree threats

The greatest threat to the quiver tree is global climate change. Weather records from across the quiver tree’s range show that average temperatures in the region have increased over past decades. Climate predictions also suggest that temperature increases will accelerate and that rainfall will decrease in the near future. As the quiver tree adapts to this change, it highlights the problems that all plants and slow-moving species face in keeping up with a rapidly changing climate ⁽⁶⁾. 

By 2001, large die-offs of quiver trees were occurring. Scientists found that most of these die-offs were occurring in the hotter equatorward areas of the quiver tree’s range, and that these die-offs were most likely caused by drought stress. In contrast, populations on the poleward range areas and at the tops of high mountains were growing and reproducing. The reason for this is that the quiver tree is responding to climate change by slowly shifting its distribution towards higher latitudes and higher altitudes ^{(6) (9)}. 

However, the quiver tree’s ability to adapt to climate change is limited by its ability to disperse across the landscape quickly enough to avoid large-scale die-back. A temperature rise of just 2 degrees Celsius would mean that the quiver tree must increase its range by over 40 kilometres every 15 years for its population to stay within a suitable climate. However, scientists have not found any new populations beyond the extremities of the species’ documented range, despite evidence that climate change has been affecting this species for a number of years. Populations at the edge of this species’ range are also genetically poorer than those in the centre of its range, making these populations more vulnerable to threats such as disease ^{(6) (9)}. 

Other, less significant threats to the quiver tree include the removal of juvenile plants by unscrupulous collectors for planting in gardens. This threat is most problematic near towns or main roads ^{(6) (7)}.

Quiver tree conservation

The quiver tree is protected by law in South Africa, where it is illegal to remove plants from the wild or collect seeds without a special permit ⁽⁷⁾. The threat posed to this species by climate change means that scientists may need to facilitate its dispersal to more suitable climates. This could be achieved by planting new trees beyond its existing range, possibly using trees from the genetically rich populations in the centre of its current range ⁽⁶⁾.

Find out more

Find out more about plant conservation in South Africa:

• South African National Biodiversity Institute:
  http://www.sanbi.org/

Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

Glossary

Inflorescence

The reproductive shoot of a plant, which bears a group or cluster of flowers.

Raceme

An inflorescence where the individual flowers all have distinct stalks.

References

1. IUCN Red List (February, 2011)
   http://www.iucnredlist.org/
2. Royal Botanic Gardens, Kew - Quiver tree (February, 2011)
   http://www.kew.org/plants-fungi/Aloe-dichotoma.htm
3. Threatened Species Programme. (2009) Interim Red Data List of South African Plant Taxa. South African National Biodiversity Institute, Pretoria, South Africa. Available at:
   http://www.sanbi.org/biodiversity/reddata.htm
4. CITES (February, 2011)
   http://www.cites.org/
5. PlantZ Africa - Quiver tree (February, 2011)
   http://www.plantzafrica.com/plantab/aloedichotoma.htm
6. IUCN (2009) Species and Climate Change: More than Just the Polar Bear. IUCN/Species Survival Commission. Cambridge, UK. Available at:
   http://www.iucn.org/what/tpas/biodiversity/resources/publications/?4562/Species-and-Climate-Change
7. BBC: H2G2 - Quiver tree (February, 2011)
   http://www.bbc.co.uk/dna/h2g2/A26151482
8. Van Wyk, B. and Van Wyk, P. (2007) How to Identify Trees in Southern Africa. Struik Publishers, Cape Town.
9. Foden, W. et al. (2007) A changing climate is eroding the geographical range of the Namib desert tree Aloe through population declines and dispersal lags. Diversity and Distributions, 13: 645-653.