Didelta

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Plant genus in the Asteraceae from Southern Africa

title: "Didelta" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["arctotideae", "asteraceae-genera", "flora-of-southern-africa"] description: "Plant genus in the Asteraceae from Southern Africa" topic_path: "general/arctotideae" source: "https://en.wikipedia.org/wiki/Didelta" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Plant genus in the Asteraceae from Southern Africa ::

Breteuillia Buc'hoz
Favonia Gaertn.
Choristea Thunb.
Distegia Klatt

Didelta is a genus of shrubs of up to 1 or 2 meter high, with two known species in the daisy family. Like in almost all Asteraceae, the individual flowers are 5-merous, small and clustered in typical heads, and are surrounded by an involucre, consisting of in this case two whorls of bracts, which are almost free from each other. The 3–5 outer bracts are protruding and triangular in shape, the inner about twice as many are lance-shaped and ascending. In Didelta, the centre of the head is taken by 3–5 clusters of bisexual yolk yellow disc florets, sometimes divided from each other by male disc florets, and is surrounded by one complete whorl of infertile yolk yellow ray florets. The common base of the flowerhead swells around the developing fruitlets, become woody and breaks into segments when ripe. The fruitlets germinate within this woody encasing. The species of the genus Didelta can be found in Namibia and South Africa. The genus is called salad thistle in English and slaaibos in Afrikaans.

Description

::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/06/Didelta_carnosa_fruiting_head.jpg" caption="url= https://repository.si.edu/bitstream/handle/10088/15979/bot_2008_pr_Funk_Chan_Gorteriinae.pdf}}"] ::

Differences between the species

D. spinosa lacks milk sap, has hairless, more or less oval leaves with spines that often enclose the stem at base, and the swollen, eventually woody segments of the receptacle containing the fruitlets lack spines. D. carnosa has milk sap, elliptic to linear, variably tomentose leaves, and the swollen and eventually woody segments of the receptacle containing the fruitlets are spiny. Two varieties are distinguished. D. carnosa var. carnosa is hairless or becomes hairless with age, while D. carnosa var. tomentosa remains densely felty hairy at least on the undersides of the leaves.

Differences with related genera

Cuspidia cernua has bristle-like pappus on top of the fruitlets and the fruiting head remains intact, while both Didelta-species have chaffy pappus and the fruiting head breaks into several triangular segments when ripe.

Taxonomy

::figure[src="https://upload.wikimedia.org/wikipedia/commons/f/fa/Didelta_tetragoniaefolia_Redouté.jpg" caption="url-access= subscription}}"] ::

; Species

Didelta carnosa (L.f.) Aiton - Cape Province, Namibia
Didelta spinosa (L.f.) Aiton - Cape Province, Namibia

Phylogeny

Based on DNA-analysis, Didelta belongs to the subtribe Gorteriinae. This analysis suggests that Didelta is most related to Berkheya spinosissima, with which it shares the dimorph involucral bracts. According to this study, the relationships within the Gorteriinae are as expressed in the following tree.

|label1=subtribe Gorteriinae |1={{clade |1= Gazania, Hirpicium, Gorteria |2={{clade |1={{clade |1= "Berkheya spinosissima" |2={{clade |1=Didelta carnosa |2=Didelta spinosa |2={{clade |1=Cuspidia |2={{clade |1=part of Berkheya including B. rigida, B. pinnatifida, B. eriobasis, B. annecteus, B. onobromoides, B. cardopatifolia |2={{clade |1=Heterorhachis |2=part of Berkheya including B. echinacea, B. rapontica, B. subulata, B. bipinnatifida, B. angolensis |3={{clade |1=part of Berkheya including B. spinosa, B. fruticosa, B. canescens |2=Cullumia and Berkheya cruciata

Reassigned species

The species that were originally described as, or moved to Didelta, which since have been reassigned include the following:

Didelta cernua = Cuspidia cernua
Didelta annua = Cuspidia cernua

Distribution

The species of the genus Didelta occur in southern Namibia and the western parts of the Northern and Western Cape provinces of South Africa.

References

Burtt, B.. (1948). "Didelta and Cuspidia". Kew Bulletin.
L'Héritier de Brutelle, Charles Louis. (1786). "Stirpes Novae: aut minus cognitae: quas descriptionibus et iconibus illustravit".
[http://www.tropicos.org/Name/40030503 Tropicos, ''Didelta'' L'Hér.]
Manning, John. (2007). "Field Guide to Fynbos". Random House Struik.
(2009). "Systematics, Evolution, and Biogeography of Compositae". International Association of Plant Taxonomy.
(2013). "Plants of the Greater Cape Floristic Region - 1: The Core Cape Flora". [[South African National Biodiversity Institute]].
(2008). "Phylogeny of the Spiny African Daisies (Compositae, tribe Arctotideae, subtribe Gorteriinae) based on trnL-F, ndhF, and ITS sequence data". Molecular Phylogenetics and Evolution.
Lindley, John. (1836). "A Natural System of Botany, Or, A Systematic View of the Organization, Natural Affinities, and Geographical Distribution, of the Whole Vegetable Kingdom: Together with the Uses of the Most Important Species in Medicine, the Arts, and Rural Or Domestic Economy". Longman, Rees, Orme, Brown, Green, and Longman.
(1960). "Nomina generica conservanda et rejicienda VI". Taxon.
[https://archive.today/20141104135133/http://dixon.iplantcollaborative.org/CompositaeWeb/Default.aspx?Page=NameDetails&TabNum=3&nameId=6f965e3d-0550-46ce-a596-30fbac6252fb Flann, C (ed) 2009+ Global Compositae Checklist ]
[http://www.theplantlist.org/tpl1.1/search?q=Didelta The Plant List, search for Didelta]

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