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This genus is accepted, and its native range is Ethiopia to Kenya, Arabian Peninsula.
A specimen from Kew's Herbarium

[FSOM]

M. Thulin et al. Flora of Somalia, Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology Stem
Stems sparsely and irregularly branched from a central stem, the branches usually horizontal but occasionally climbing if supported by other vegetation, 4-angled, usually tapering towards the tip, grey to brownish, the surface markedly wrinkled or bullate and papillate, the angles rounded and often quite indistinct; latex clear
Morphology Leaves
Leaves scale-like, appressed to stem, soon falling
Morphology Reproductive morphology Inflorescences
Flowers solitary or up to 3 together, scattered along stem but mostly in upper part, opening successively; pedicel short to almost absent
Morphology Reproductive morphology Flowers Corolla
Corolla variously shaped, mostly rotate or shallowly campanulate; tube short to almost absent; lobes ovate-triangular to linear, in some species joined at the tips
Morphology Reproductive morphology Flowers Corona
Corona gynostegial, double, with lobes varying in shape
Morphology Reproductive morphology Fruits
Follicles terete, slender, widely diverging
Morphology Reproductive morphology Seeds
Seeds with a tuft of hairs at one end.
Distribution
Genus of 17 species in the Horn of Africa and the southern part of the Arabian Peninsula

[FTEA]

Apocynaceae (part 2), David Goyder, Timothy Harris, Siro Masinde, Ulrich Meve, Johan Venter. Flora of Tropical East Africa, 2012

Morphology General Habit
Creeping or erect stem-succulents, often scrambling in bushes, sparsely branched from main stem.
Morphology General Exudate
Latex mostly slightly milky.
Morphology Stem
Stems cylindrical, roundly 4-angled, papillose or tessellate, thickly wax-covered
Morphology Leaves
Leaf rudiments strongly ascending, caducuous; stipules glandular, globoid
Morphology Reproductive morphology Inflorescences
Inflorescences 1–3-flowered, lateral, slightly sunken
Morphology Reproductive morphology Flowers Corolla
Corolla rotate or elongated-conical, basally fused, abaxially papillose, glabrous, papillose or hairy; corolla lobes linear, lanceolate or ovate, spreading (in the one Kenyan species) or remaining connected at tips
Morphology Reproductive morphology Flowers Corona
Corolline corona absent. Gynostegial corona in 2 series: “outer” corona of 5 staminal and 5 interstaminal parts fused basally up to half of length, rotate to cyathiform, interstaminal corona subulate, deltoid or 2-lobed, erect or reflexed; “inner” staminal corona lingulate, triangular or rectangular, inflexed
Morphology Reproductive morphology Flowers Gynostegium
Gynostegium sessile
Morphology Reproductive morphology Flowers Pollinia
Pollinia ovoid or pyriform
Morphology Reproductive morphology Fruits
Mericarps two
Note
Around 13 species (depending on the species concept) in NE Africa and Arabia. A genus in close but complex and still not fully understood relationship to Echidnopsis.

Native to:

Ethiopia, Kenya, Oman, Saudi Arabia, Somalia, Yemen

Rhytidocaulon P.R.O.Bally appears in other Kew resources:

Date Reference Identified As Barcode Type Status
Collenette, J.S. [7465] 58879.000

First published in Candollea 18: 335 (1963)

Accepted by

  • Albers, F. & Meve, U. (eds.) (2002). Illustrated handbook of succulent plants Asclepiadaceae, corr. 2nd printing: 1-318. Springer, Berlin, Heidelberg,New York.
  • Goyder, S., Harris, T., Masinde, S., Meve, U. & Venter, J. (2012). Flora of Tropical East Africa, Apocynaceae(2): 1-530.

Literature

Flora of Somalia

  • Bruyns in Edinb. J. Bot. 56: 211–228 (1999).
  • Flora Somalia, Vol 3, (2006) Author: by J. Lavranos [updated by M. Thulin 2008]

Flora of Somalia
Flora of Somalia
http://creativecommons.org/licenses/by-nc-sa/3.0

Flora of Tropical East Africa
Flora of Tropical East Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Herbarium Catalogue Specimens

Kew Backbone Distributions
The International Plant Names Index and World Checklist of Selected Plant Families 2021. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2021. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0