Isotoma (plant)

Isotoma is a genus of annual and perennial herbs in the family Campanulaceae and are native to Australia and New Zealand.

Isotoma
Isotoma petraea
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Campanulaceae
Subfamily: Lobelioideae
Genus: Isotoma
Lindl.[1]
Synonyms[1]

Description

Plants in the genus Isotoma have milky sap, a distinct taproot and sometimes adventitious roots along the branches. The leaves are arranged alternately and are usually toothed or lobed. The flowers are solitary in leaf axils or arranged in groups on the ends of branchlets. The sepals form a short tube with lobes. The petal tube is slightly zygomorphic with five lobes spreading horizontally, the upper two smaller and the lower three often with distinct markings. The stamens are fused to the petal tube. The fruit is an urn-shaped or conical capsule containing a large number of minute seeds.[2][3]

Taxonomy and naming

In 1810, in his book Prodromus Florae Novae Hollandiae et Insulae Van Diemen, Robert Brown described Lobelia hypocrateriformis and placed it in section Isotoma.[4][5] Then in 1826, based on Brown's description, John Lindley raised the genus Isotoma in The Botanical Register.[6][7] The name Isotomais derived from ancient Greek words meaning "equal" and "a piece cut off" or "a slice". The name was originally applied to the section Isotoma because those species differ from true lobelias in having petal lobes that are almost equal in size.[8]

Species list

The following is a list of species and subspecies accepted by the World Flora Online as at April 2020:[9]

In New Zealand, Isotoma rivalis is considered to be a synonym of Lobelia ionantha Heenan.[10][11][12]

References
  1. "Isotoma". Australian Plant Census. Retrieved 11 April 2020.
  2. Wiecek, Barbara M. "Genus Isotoma". Royal Botanic Garden Sydney. Retrieved 11 April 2020.
  3. Albrecht, David E.; Walsh, Neville G. "Isotoma". Royal Botanic Gardens, Victoria. Retrieved 11 April 2020.
  4. "Lobelia sect. Isotoma". APNI. Retrieved 11 April 2020.
  5. Brown, Robert (1810). Prodromus florae Novae Hollandiae et insulae Van-Diemen, exhibens characteres plantarum quas annis 1802-1805. London: Typis R Taylor, veneunt apud J. Johnson. p. 565. Retrieved 11 April 2020.
  6. "Isotoma". APNI. Retrieved 11 April 2020.
  7. Lindley, John (1826). "The Botanical Register". The Botanical Register. 12: 964. Retrieved 11 April 2020.
  8. Francis Aubie Sharr (2019). Western Australian Plant Names and their Meanings. Kardinya, Western Australia: Four Gables Press. p. 88. ISBN 9780958034180.
  9. "Search Isotoma". World Flora Online Consortium. Retrieved 11 April 2020.
  10. "Lobelia ionantha". Landcare Research Manaaki Whenua. Retrieved 11 April 2020.
  11. "Lobelia ionantha". New Zealand Plant Conservation Network. Retrieved 11 April 2020.
  12. Knox, E. B.; Heenan, P. B.; Muasya, A. M.; Murray, B. G. (2008). "Phylogenetic position and relationships of Lobelia glaberrima (Lobeliaceae), a new alpine species from southern South Island (New Zealand)". New Zealand Journal of Botany. 46 (1): 77–85. doi:10.1080/00288250809509755.
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