The Hermannia Pages:
Contents and Overview

Malvaceae Info (home)


Contents

  • Introduction
  • Classification
  • Distribution
  • Cytology
  • Photographs (Links)
  • References
  • Hermannia Gallery (photos)

  • Introduction

    Hermannia is a genus within the family Malvaceae sensu APG, previously placed in Sterculiaceae or Byttneriaceae. It is particularly closely related to Dicarpidium, Melochia and Waltheria. The 100 plus species of Hermannia have a mostly African and extratropical distibution, with a few species in other dry subtropical regions, from North America to Australia.

    Hermannias are perennial herbs, subshrubs or shrubs. The flowers are yellow, or less often red, orange, violet or white.

    Some species of Hermannia are toxic.

    [ These pages are currently rather sketchy. A page had been produced for Gilesia before Bayer's revision of Malvaceae; an outline of The Hermannia Pages has been produced to provide a context a revised "Gilesia" page. ]

    Hermannia is distinguished from Melochia, Walteria and Dicarpidium by the possesions of 5 antesepalous ovary locules with several to many ┬▒horizontal ovules; Melochia has antepetalous locules with two ascending ovules, Dicarpidium is biloculate and Waltheria uniloculate.

    Classification

    Hermannia is a genus of the subfamily Byttnerioideae and tribe Hermanieae of the family Malvaceae (previously Sterculiaceae). There are variously stated to be between 100 and 300 species. From a combination of sources I have collected a figure of 192 species. The distribution is centred in southern Africa, where there are 30 species in Cape Province, and many more elsewhere in the region, and extends through tropical East Africa to North East Africa, the West African savannas (1 species) and Arabia (2 species). There are also 3 species in northern Mexico and adjacent parts of the United States, a single species in southern Mexico, and a single species in Australia.

    One of the Arabian species has been placed in a monotypic Trichanthera, Eurynema or Kurria, and the Australian species in a monotypic Gilesia or Hymenocapsa. A group of South African species are sometimes separated as Mahernia, which is otherwise treated as a section within Hermannia.

    The genus was introduced by Tournefort, but as taxonomic priority is conventionally started with Linnaeus's Species Plantarum of 1753, it is usually ascribed to Linnaeus. Tournefort named the genus after Paul Hermann, who was Professor of Botany at Leyden in the latter part of the seventeenth century

    The wide diversity of species in a restricted geographical region is suggestive of a recent origin and diversification of the species. The lack of reported variation in chromosome counts may be further evidence in favour of this interpretation, or may reflect a limited sampling of the species of the genus. On the other hand the genus seems less derived that the other genera of the tribe (e.g. in the presence of 5-locular ovaries with pluri-ovulate locules, which is a widespread condition in Byttneroideae, whereas the other genera show reduction in both the number of locules and ovules). Combining this observation with the disjunct distribution suggests that it may be worth testing the hypothesis that Hermannia is polyphyletic.

    Distribution

    As mentioned above the distribution is centred in southern Africa, but the genus is also found in Madagascar, and extends through tropical East Africa (14 species, some shared with southern Africa) to North East Africa (4 species, possibly more) and Arabia (one species, also found in Egypt and Sudan). A single species (Hermannia tigrensis) is found in western Africa as well as southern Africa and North East Africa. There are 3 species in northern Mexico and adjacent parts of the United States, a single species in southern Mexico, and a single species in Australia.

    Southern Africa has nearly 150 species, including some of those found further north in Africa. The greatest diversity is within Cape Province and Namibia, but there are relatively few species witin the southern coastal areas of Cape Province (Cape Floristic Province). The other South African provinces have between 18 (Gaufeng) and 34 (Free State) species. There are 8 species in Lesotho, 20 in Botswana and 13 in Swaziland. There are perhaps 20 species in southern tropical Africa, of which 12 occur in Zimbabwe, 3 of which are also found in Zambia. Mozambique has 6 species, 4 of which are also shared with Zimbabwe. At least 6 species occur in Angola. The majority of the remaining species are presumably to be found in Natal, Transvaal, the Orange Free State, Namibia and Angola. Madagascar has a single species (Hermannia exappendiculata) which is shared with East and North East Africa.

    For further details on the distribution of species in southern Africa see the Malviflora of Southern Africa. For further details on the distribution of species in eastern Africa see the Malviflora of Eastern Africa.

    Cytology

    Bayer and Kubitzki [1] state that the chromosome count is 12.

    Images

    Photographs of various species of Hermannia can be found on the web. A partial list follows.

    References

    1. Bayer, in Kubitzki & Bayer, The Families and Genera of Vascular Plants, Vol. 5 (2003)

    Feedback

    If you have found any errors on this page, or have any further information about the genus Hermannia then please contact me at webmaster@meden.demon.co.uk.


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