Duvalia

Life-forms

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Cladus: Asterids
Cladus: Lamiids
Ordo: Gentianales

Familia: Apocynaceae
Subfamilia: Asclepiadoideae
Tribus: Ceropegieae
Subtribus: Stapeliinae
Genus: Duvalia
Species: D. angustiloba – D. caespitosa – D. corderoyi – D. eilensis – D. elegans – D. galgallensis – D. gracilis – D. immaculata – D. maculata – D. modesta – D. parviflora – D. pillansii – D. polita – D. pubescens – D. somalensis – D. sulcata – D. velutina – D. vestita
Source(s) of checklist:
Name

Duvalia Haw.
Homonyms

Duvalia Bonpl. = Hypocalyptus Thunb.

Synonyms

Duvallia Haw.. 1812

Distribution
Native distribution areas:

Continental: Africa
Angola, Botswana, Cape Provinces, Caprivi Strip, Djibouti, Ethiopia, Free State, KwaZulu-Natal, Lesotho, Malawi, Mozambique, Namibia, Northern Provinces, Saudi Arabia, Somalia, Sudan, Swaziland, Yemen, Zambia, Zimbabwe

References: Brummitt, R.K. 2001. TDWG – World Geographical Scheme for Recording Plant Distributions, 2nd Edition
References
Primary references

Haworth, A.H. 1812. Synopsis plantarum succulentarum: cum descriptionibus, synonymis, locis, observationibus anglicanis, culturaque. 334 pp. London: R. Taylor. BHL Reference page. : 44

Links

Govaerts, R. et al. 2021. Duvalia in Kew Science Plants of the World online. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the internet. Accessed: 2021 Feb 07. Reference page.
International Plant Names Index. 2021. Duvalia. Published online. Accessed: Feb 07 2021.
Tropicos.org 2021. Duvalia. Missouri Botanical Garden. Published on the internet. Accessed: 2021 Feb 07.
Hassler, M. 2021. Duvalia. World Plants: Synonymic Checklists of the Vascular Plants of the World In: Roskovh, Y., Abucay, L., Orrell, T., Nicolson, D., Bailly, N., Kirk, P., Bourgoin, T., DeWalt, R.E., Decock, W., De Wever, A., Nieukerken, E. van, Zarucchi, J. & Penev, L., eds. 2021. Species 2000 & ITIS Catalogue of Life. Published on the internet. Accessed: 2021 Feb 07. Reference page.

Vernacular names

Duvalia is a succulent plant genus in the subfamily Asclepiadoideae, in the family Apocynaceae (dogbane).

The genus was first described in 1812, named after the French physician and botanist Henri-Auguste Duval (1777-1814).[1]

Description
The rare Duvalia parviflora has smooth "potato-shaped" stems and tiny, cream-coloured flowers.
Duvalia elegans, the type species of the genus, showing its wider, triangular flower lobes.
The hairy flowers of Duvalia vestita (Duvalia caespitosa subsp. vestita).
Duvalia caespitosa, one of the commonest and most widespread species, from the west of South Africa

Vegetative

The Duvalia species are succulent, perennial plants with low, planar growth. The stems are clavate, cylindrical to spherical, in cross-section four-, five-or six-edged, and to about 10 inches long. They can range from green, gray to mottled reddish in color.

The stems of some species, such as the rounded Duvalia parviflora, are distinctive, and these species can be identified even when not in flower. However the stems are very variable, and most Duvalia species can only be distinguished from each other when the flower is seen.

The stems are superficially very similar to those of the related genus Piaranthus, and the two are often confused when not in flower. In cross-section, Duvalia stems are sometimes five or six sided (Piaranthus stems are always four-sided in cross-section). To accurately distinguish them however, it is necessary to examine the flowers.
Floral

The distinctive flowers are on long, bare stalks, which grow from the base of the stems.

Each flower has five thin, elongated petal-like lobes, radiating in a star-shape, from a central raised disk or annulus.

The colour of most species flowers is shades of reddish brown, except for those of the rare Duvalia parviflora which are cream-coloured. The hermaphroditic flowers measure 1–5 cm in diameter, and have five parts. The crown is yellow ocher, brown, red to dark purple. The five corolla lobes are flat or folded along the middle nerve.

Distribution

It occurs in southern Africa. The majority of the species are restricted to the western part of South Africa & Namibia, with the greatest number of species occurring in the Great Karoo region, on the edge of the winter rainfall area. Only one species, Duvalia polita extends further east, and as far north into tropical Africa as Malawi and Zambia.[2][3]

Four species, occurring on the other side of the continent on the verges of the Red Sea, were formerly included in the genus Duvalia. However phylogenetic studies have shown them to be relatively unrelated to the rest of the genus, and more closely related to genus Ballyanthus Bruyns.[4]

Species[5]

Duvalia anemoniflora (Deflers) R.A. Dyer & Lavranos - Arabia
Duvalia angustiloba N.E.Br. - South Africa
Duvalia caespitosa (Masson) Haw. - South Africa
Duvalia corderoyi (Hook.f.) N.E.Br. - South Africa
Duvalia eilensis Lavranos - Somalia
Duvalia elegans (Masson) Haw. - Cape Province
Duvalia galgallensis Lavranos - Somalia
Duvalia gracilis Meve - Cape Province
Duvalia immaculata (C.A.Lückh.) M.B.Bayer ex L.C.Leach - South Africa
Duvalia maculata N.E.Br. - South Africa
Duvalia modesta N.E.Br. - South Africa
Duvalia parviflora N.E.Br. - Cape Province
Duvalia pillansii N.E.Br. - Cape Province
Duvalia polita N.E.Br. - South Africa
Duvalia pubescens N.E.Br. - Cape Province
Duvalia somalensis Lavranos - Somalia
Duvalia sulcata N.E.Br. - Arabia
Duvalia velutina Lavranos - Saudi Arabia
Duvalia vestita Meve - Cape Province

formerly included[5]

transferred to Mannia

Duvalia rupestris now Mannia rupestris
References

Haworth, Adrian Hardy. 1812. Synopsis Plantarum Succulentarum: cum descriptionibus, synonymis, locis, observationibus anglicanis, culturaque 44.
Tropicos Duvalia
Gibbs Russell, G. E., W. G. M. Welman, E. Retief, K. L. Immelman, G. Germishuizen, B. J. Pienaar, M. Van Wyk & A. Nicholas. 1987. List of species of southern African plants. Memoirs of the Botanical Survey of South Africa 2(1–2): 1–152(pt. 1), 1–270(pt. 2).
P. Bruyns, C. Klak, P. Hanacek: Evolution of the stapeliads (Apocynaceae-Asclepiadoideae) - repeated major radiation across Africa in an Old World group. Molecular Phylogenetics and Evolution. 2014. v. 77, no. 1, p. 251--263. ISSN 1055-7903.
The Plant List, Duvalia