Allium dregeanum
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Amaryllidaceae
Subfamily: Allioideae
Genus: Allium
Subgenus: A. subg. Allium
Species:
A. dregeanum
Binomial name
Allium dregeanum
Kunth

Allium dregeanum is the sole known species of Allium endemic to sub-Saharan Africa.[1] It has also been described as the only Allium species endemic to the Southern Hemisphere,[2][3] though some descriptions of the genus also include Allium juncifolium (Chile) and Allium sellovianum (Brazil),[4][5] which are much less studied than Allium dregeanum. The distribution of Allium dregeanum extends from the summer-rainfall region, into the winter-rainfall zone of South Africa.[6] Since Allium species are almost exclusively found in the Northern Hemisphere, with major centers of diversity in Central Asia and western North America,[2] the biogeographical history of Allium dregeanum is of interest.

Though some theories have been put forward, no explanation for the geographic isolation of Allium dregeanum has been confirmed. In 1976, De Wilde-Dufyes proposed that Allium dregeanum is a modification of the European species Allium ampeloprasum, and may have been brought to South Africa by early European settlers.[6] De Saarker et al. contradicted this theory in 1997, when they explored genetic similarities between Allium dregeanum and Allium ampeloprasum, and did not find evidence of a significant genetic relationship. They also point to evidence that Allium dregeanum was already established in South Africa in the mid-17th century, when the first Dutch settlers colonized South Africa, but do not suggest other explanations for Allium dregeanum's isolation.[1]

Allium dregeanum occurs at elevations of 100-1000m, and flowers in spring and early summer (October to December).[6] It can grow to 0.6m by 0.2m, growing best in well-drained soils in sunny areas.[7] Allium dregeanum is also notable for its high chromosome counts: polyploidy is not uncommon in Allium, with 14% of representative Allium species exhibiting more than two sets of chromosomes,[8] but Allium dregeanum has particularly high ploidy levels, and can be octoploid or decaploid.[1]

References

  1. 1 2 3 De Sarker, D.; Johnson, M.A.T.; Reynolds, A.; Brandham, P.E. (June 1997). "Cytology of the highly polyploid disjunct species, Allium dregeanum (Alliaceae), and of some Eurasian relatives". Botanical Journal of the Linnean Society. 124 (4): 361–373. doi:10.1006/bojl.1997.0109.
  2. 1 2 Li, Qin-Qin; Zhou, Song-Dong; He, Xing-Jin; Yu, Yan; Zhang, Yu-Cheng; Wei, Xian-Qin (November 2010). "Phylogeny and biogeography of Allium (Amaryllidaceae: Allieae) based on nuclear ribosomal internal transcribed spacer and chloroplast rps16 sequences, focusing on the inclusion of species endemic to China". Annals of Botany. 106 (5): 709–733. doi:10.1093/aob/mcq177. PMC 2958792. PMID 20966186.
  3. ↑ Fay, Michael F.; Rudall, Paula J.; Chase, Mark W. (2006). "Molecular studies of subfamily Gilliesioideae (Alliaceae)". Aliso. 22: 367–371. doi:10.5642/aliso.20062201.30. Retrieved December 29, 2015.
  4. ↑ Block, Eric (2010). Garlic and Other Alliums. Cambridge, UK: The Royal Society of Chemistry. p. 12. ISBN 978-0-85404-190-9.
  5. ↑ El Shabrawy, Mona O.A.; Hosna, Hassnaa A.; El Garf, Ibrahim A.; Marzouk, Mona M.; Kawashty, Salwa A.; Saleh, Nabiel A.M. (October 2014). "Flavonoids from Allium myrianthum Boiss". Biochemical Systematics and Ecology. 56: 125–128. doi:10.1016/j.bse.2014.05.015.
  6. 1 2 3 De Wilde-Duyfjes, Brigitta E.E. (1976). "A revision of the genus Allium L. (Liliaceae) in Africa". Mededelingen Landbouwhogeschool Wageningen. 76: 1–237.
  7. ↑ "Allium dregeanum". Plants for a Future. Retrieved December 30, 2015.
  8. ↑ Friesen, Nikolai; Fritsch, Reinhard M.; Blattner, Frank R. (January 2006). "Phylogeny and new intrageneric classification of Allium (Alliaceae) based on nuclear ribosomal DNA ITS sequences". Aliso. 22 (1): 372–395. doi:10.5642/aliso.20062201.31.
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