Aloe dichotoma

Quiver tree
Scientific classification
Kingdom: Plantae
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Xanthorrhoeaceae
Subfamily: Asphodeloideae
Genus: Aloe
Species: A. dichotoma
Binomial name
Aloe dichotoma
Masson
Subspecies

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.

In cultivation it requires extremely well-drained coarse mineral soil, full sun, good aeration and extremely little water - primarily in the winter (as it mainly occurs in winter rainfall desert).

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.

Gallery

See also

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

External links

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