Aloe dichotoma

Quiver tree
Scientific classification
Kingdom:	Plantae
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Asphodelaceae
Subfamily:	Asphodeloideae
Genus:	Aloe
Species:	A. dichotoma
Binomial name
Aloe dichotoma Masson
Subspecies
A. dichotoma subsp. dichotoma Masson A. dichotoma subsp. pillansii (L.Guthrie) Zonn. A. dichotoma subsp. ramosissima (Pillans) Zonn.

Aloe dichotoma (the quiver tree or kokerboom) is a tall, branching species of aloe, indigenous to Southern Africa, specifically in the Northern Cape region of South Africa, and parts of Southern Namibia.

Naming

Known as Choje to the indigenous San people, the quiver tree gets its English common name from the San people practice of hollowing out the tubular branches of Aloe dichotoma to form quivers for their arrows. The species name "dichotoma" refers to how the stems repeatedly branch into two ("dichotomous" branching) as the plant grows.

Subspecies and taxonomy

Close-up photo of bark on a quiver tree.

The World Checklist of Selected Plant Families currently recognizes three subspecies, A. dichotoma subsp. dichotoma, A. dichotoma subsp. pillansii and A. dichotoma subsp. ramosissima.^[1]

These are also treated as three separate species, A. dichotoma, A. pillansii and A. ramosissima, which are then grouped within the Dracoaloe subsection of the genus Aloe. All inhabit the same arid areas of the Richtersveld and the Namib Desert around the South African-Namibian border. Treated as separate species, the three have been given different ratings on the IUCN Red List of Threatened Species: 'vulnerable' for A. dichotoma, 'critically endangered' for A. pillansii and 'endangered' for A. ramossisima.

The three subspecies can be distinguished. In A. dichotoma subsp. pillansii, the inflorescences hang from below the lowest leaves, rather than growing erect. A. dichotoma subsp. ramosissima is considerably smaller - rarely reaching more than 2 m in height - and assumes a more shrub-like shape. While there is a gradation between tree-like dichotoma and the shrubby ramosissima, the relatively unique pillansii population is separated by a different flowering time and therefore does not interbreed with the other two subspecies.^[2]

Distribution and conservation

Distribution map showing Aloe dichotoma (light blue) in southern Africa

One of the few examples of spontaneous forests of A. dichotoma is the Quiver Tree Forest, about 14 km north of Keetmanshoop, in Namibia. Another is located in the Northern Cape of South Africa at Gannabos.

Throughout much of its range this species is in decline. Modeling of Aloe dichotoma in South Africa and Namibia has contributed to understanding the needs of protected areas in response to climate change. Modelled range declines in this species due to climate change have recently been confirmed by field surveys.^[3]

Cultivation

Aloe dichotoma is cultivated in arid areas around the world, for use in landscaping. The slow growth rate and relative rarity of the plant make it a particularly expensive specimen. It is also relatively difficult to keep outside of its natural habitat.

In cultivation it requires extremely well-drained coarse mineral sand (preferably with some loam and bone meal to keep it active and growing), full sun, good aeration and extremely little water - primarily in the winter (as it mainly occurs in winter rainfall desert). In the (rare) event that it is under-watered, the leaves will curl up and die off at the tips; this is not fatal, but indicates that it is relatively dry.

It is unusually prone to aphids and insect infections in between its leaves, and this is exacerbated whenever there is not full sun and constant fresh air movement. Indoor plants require frequent treatment for these pests. Fungicide can also be added occasionally, to protect from rot.

It can be propagated from seed and (with more difficulty) from cuttings or truncheons. Cuttings need to be thoroughly dried for several weeks in a shaded area, before being planted.^[4]

Gallery

• 

  Quiver trees in a greenhouse

• 

  Aloe dichotoma in bloom

• 

  Quiver tree in southern Namibia

• 

  Growth of a young Aloe dichotoma from May to August

• 

  Quiver tree at Fish River Canyon, Namibia.

• 

  Quiver Tree Forest near Keetmanshoop, Namibia, in the evening.

• 

  Sociable Weaver (Philetairus socius) nest in a Quiver tree. Northern Cape, South Africa.

• 

  Quiver tree in flower in the Augrabies National Park, South Africa.

• 

  The flowers of the Quiver tree in May. Augrabies National Park, South Africa.

See also

• Aloe pillansii (syn. for A. dichotoma subsp. pillansii)
• Aloe ramosissima (syn. for A. dichotoma subsp. ramosissima)
• Aloe barberae

References

1. WCSP (2011), World Checklist of Selected Plant Families, The Board of Trustees of the Royal Botanic Gardens, Kew, retrieved 2011-05-23, search for "Aloe dichotoma"
2. Court, D. (2010), Succulent Flora of Southern Africa, Cape Town: Struik Nature, ISBN 978-1-77007-587-0
3. Foden, Wendy; Midgley, Guy F.; Hughes, Greg; Bond, William J.; Thuiller, Wilfried; Hoffman, M. Timm; Kaleme, Prince; Underhill, Les G.; et al. (2007), "A changing climate is eroding the geographical range of the Namib Desert tree Aloe through population declines and dispersal lags" (PDF), Diversity and Distributions, 13 (5): 645–653, doi:10.1111/j.1472-4642.2007.00391.x, retrieved 2011-07-16
4. "Aloe dichotoma". Retrieved 26 September 2016.

External links

• Desert-tropicals.com profile
• Plantzafrica.com profile
• Dressler, S.; Schmidt, M. & Zizka, G. (2014). [http://www.africanplants.senckenberg.de/root/index.php?submitForm=true&page_id=77&searchTextMenue=Aloidendron+dichotomum&filterRegionIDs[]=6&filterRegionIDs[]=1&filterRegionIDs[]=2&filterRegionIDs[]=3&filterRegionIDs[]=5 "Aloidendron dichotomum"]. African plants – a Photo Guide. Frankfurt/Main: Forschungsinstitut Senckenberg.