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Ottelia

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Ottelia
Ottelia alismoides
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Alismatales
Family: Hydrocharitaceae
Subfamily: Anacharioideae
Genus: Ottelia
Pers. 1805 not R.Hedw. 1806
Synonyms[1]
  • Damasonium Schreb. 1789, illegitimate homonym, not Mill. 1754 (Hydrocharitaceae) nor Adans. 1789 (syn of Limnocharis in Alismataceae)
  • Hymenotheca Salisb.
  • Boottia Wall.
  • Oligolobos Gagnep.
  • Xystrolobos Gagnep.
  • Beneditaea Toledo

Ottelia is a genus of an aquatic plant family Hydrocharitaceae described as a genus in 1805.[2][3] The genus is native to tropical and subtropical regions of Africa, Asia, South America, and Australia.[4][5]

Description

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The genus is highly variable, with a variety of features.[6] It contains aquatic herbs with crowded leaves. Some of the leaves are held on short stems. Others float on long stems. The rooting stem is long.[7]

The flowers are held in a herbaceous bract that is many nerved and has two to six clear ribs. The tubular spathe is shortly divided into two.[7]

Each flower has two rows of a trimerous perianth held above the beak of the ovary. The rigid outer layer is oblong or linear. The larger inner layer is petal-like with a fleshy appendage at the base.[7] There are six or more stamens, often with flattened filaments.[7] The ovary is oblong and beaked with strongly developed placentas dividing it into six chambers that contain many ovules. There are six linear styles that are partially split in two.[7]

The tapering oblong fruits are included in the floral bract and have three to six wings. They contain numerous small, oblong seeds.[7]

It has been suggested that this genus should be divided into two subgenera and four sections:[8]

  • Subgenus Ottelia has bisexual flowers.
    • Section Ottelia: The spathes have a single flower and six to nine carpels in the ovary.
    • Section Oligolobos: The spathes have many flowers and an ovary with three carpels.
  • Subgenus Boottia has unisexual flowers. The male spathes have one to many flowers while the female spathes always have many flowers.
    • Section Boottia: The males spathes have one flower and the ovaries of the female flowers have nine to fifteen carpels.
    • Section Xystrolobos: The female spathes have two to many flowers and an ovary with three or nine carpels.

Distribution

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This genus is found throughout the Paleotropics, from Africa to Asia to Australia and New Caledonia and to Brazil.[8] The areas with the highest diversity occur in central Africa (about 13 species) and south east Asia (about 8 species).[5][6]They are mostly found growing in lakes, slow flowing creeks and rivers.[9]

Phylogenomics and evolution

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Originating in the mid Miocene, this genus now consists of two major clades that correspond to the two major centers of diversity - Africa and Asia. Morphological evidence suggests that this genus originated in Africa. It then spread to South America and Australasia via the ocean, and then from Australasia to Asia.[6]

Global cooling, the development of the East Asian monsoon climate and tectonic movement likely aided diversification in China. The movement of the Yunnan-Guizhou Plateau Pin the liocenehas been suggested to explain the high endemism of Chinese species of Ottelia.[6]

Species

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This genus is the second largest in its family (Hydrocharitaceae).[6] The following species are accepted:[1]

  1. Ottelia acuminata (Gagnep.) Dandy - S China
  2. Ottelia alismoides (L.) Pers. - Khabarovsk, Primorye, China, Indian Subcontinent, SE Asia, New Guinea, Solomon Is, N Australia
  3. Ottelia balansae (Gagnep.) Dandy - S China, Vietnam
  4. Ottelia brachyphylla (Gürke) Dandy - Sudan
  5. Ottelia brasiliensis (Planch.) Walp. - Brazil, Paraguay, NE Argentina
  6. Ottelia cordata (Wall.) Dandy - Hainan, Thailand, Myanmar, Cambodia
  7. Ottelia cylindrica (T.C.E.Fr.) Dandy - Zaïre, Zambia, Angola
  8. Ottelia emersa Z.C.Zhao & R.L.Luo - Guangxi
  9. Ottelia exserta (Ridl.) Dandy - from Somalia to Cape Province
  10. Ottelia fengshanensis Z.Z.Li, S.Wu & Q.F.Wang - from southeast China
  11. Ottelia fischeri (Gürke) Dandy - from Kenya to Mozambique
  12. Ottelia guanyangensis Z.Z.Li, Q.F.Wang & S.Wu - from Southeast China
  13. Ottelia kunenensis (Gürke) Dandy - Zambia, Angola, Botswana, Namibia
  14. Ottelia lisowskii Symoens - Zaïre, Zambia
  15. Ottelia mesenterium (Hallier f.) Hartog - Sulawesi
  16. Ottelia muricata (C.H.Wright) Dandy - C + S Africa
  17. Ottelia obtusifolia T.C.E.Fr. - from Zambia and Zaïre
  18. Ottelia ovalifolia (R.Br.) Rich. - Australia
  19. Ottelia profundecordata Symoens - from the Central African Republic and Zaïre
  20. Ottelia scabra Baker - South Sudan, Uganda
  21. Ottelia ulvifolia (Planch.) Walp. - trop + S Africa, Madagascar
  22. Ottelia verdickii Gürke - Tanzania, Zaïre, Zambia, Angola

Conservation

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The species belonging to this genus are being increasingly negatively impacted by the use and pollution of their water bodies. They have also been declining as a result of climate change. This will continue to occur as climate change accelerates habitat fragmentation and habitat loss due to changing conditions, including increasing water temperatures.[9]

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  • Flower of Ottelia alismoides
    Flower of Ottelia alismoides

References

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  1. ^ a b "World Checklist of Selected Plant Families: Royal Botanic Gardens, Kew". apps.kew.org. Retrieved 2017-02-01.
  2. ^ Persoon, Christiaan Hendrik. 1805. Synopsis plantarum,seu Enchiridium botanicum, complectens enumerationem systematicam specierum hucusque cognitarum 1: 400 in Latin
  3. ^ Cook, C.D.K., Symoens, J.-J. Urmi- Konig, K. (1984) A revision of the genus Ottelia (Hydrocharitaceae). 1. Generic considerations Aquatic Botany 18: 263-274
  4. ^ "Ottelia Pers". Plants of the World Online. Retrieved 2022-11-09.
  5. ^ a b Cook, C.D.K. and Urmi- Konig, K. (1984) A revision of the genus Ottelia (Hydrocharitaceae). 2. The species of Eurasia, Australasia and America Aquatic Botany 20: 131–177
  6. ^ a b c d e Li, Zhi-Zhong; Lehtonen, Samuli; Martins, Karina; Gichira, Andrew W.; Wu, Shuang; Li, Wei; Hu, Guang-Wan; Liu, Yan; Zou, Chun-Yu; Wang, Qing-Feng; Chen, Jin-Ming (2020-11-01). "Phylogenomics of the aquatic plant genus Ottelia (Hydrocharitaceae): Implications for historical biogeography". Molecular Phylogenetics and Evolution. 152: 106939. Bibcode:2020MolPE.15206939L. doi:10.1016/j.ympev.2020.106939. ISSN 1055-7903. PMID 32791299. S2CID 221121993.
  7. ^ a b c d e f Phillips, Edwin Percy (1951). The genera of South African flowering plants. South Africa: Government Printer.
  8. ^ a b Hen, Li (1981). "Classification, distribution and phylogeny of the genus Ottelia". Journal of Systematics and Evolution. 19 (1): 29–42.
  9. ^ a b Ngarega, Boniface K.; Nzei, John M.; Saina, Josphat K.; Halmy, Marwa Waseem A.; Chen, Jin-Ming; Li, Zhi-Zhong (2022-09-01). "Mapping the habitat suitability of Ottelia species in Africa". Plant Diversity. 44 (5): 468–480. Bibcode:2022PlDiv..44..468N. doi:10.1016/j.pld.2021.12.006. ISSN 2468-2659. PMC 9512647. PMID 36187550.
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