imported>OAbot: Open access bot: doi added to citation with #oabot.

2023-01-28T22:30:40Z

Open access bot: doi added to citation with #oabot.

New page

{{Short description|Genus of flowering plants}}
{{Automatic taxobox
|image = Tylecodon paniculatum MS 9570.jpg
|image_caption = ''[[Tylecodon paniculatus]]''
|taxon = Tylecodon
|authority = Toelken{{sfn|Tölken|1978}}
}}

'''''Tylecodon''''' is a genus of [[succulent plant]]s in the family [[Crassulaceae]], native to [[southern Africa]].

Until the late 1970s all these plants were included in the genus ''[[Cotyledon (genus)|Cotyledon]]'', but in 1978 [[Helmut Toelken]] of the Botanical Research Institute, [[Pretoria]], split them off into a genus of their own.{{sfn|Tölken|1978}}

==Description and taxonomy==

The grounds for splitting ''Cotyledon'' to create the new genus included certain features of the flowers, but more conspicuously, the leaves of ''Tylecodon'' are deciduous in summer and they are borne in a spiral arrangement, rather than the [[Phyllotaxis|opposite]], [[Decussation|decussate]] arrangement of ''Cotyledon'' leaves.

[[File:Tylecodon racemosus.jpg|thumb|left|Detail of ''[[Tylecodon racemosus]]'' flowers]]
[[File:Tylecodon paniculatus - Cape Peninsula CapeTown SA 1.JPG|thumb|left|''[[Tylecodon paniculatus]]'' in summer, without leaves]]
The species are very varied, ranging from dwarf succulents such as ''[[Tylecodon reticulatus]]'' to ''[[Tylecodon paniculatus]]'', which may exceed two metres in height.

The new name ''Tylecodon'' was apparently chosen as a syllabic [[anagram]] of the earlier name ''[[Cotyledon (genus)|Cotyledon]]''.

[[File:5 Tylecodon wallichii - Montagu RSA.jpg|thumb|right|''[[Tylecodon wallichii]]'']]
[[File:Tylecodon reticulatus.jpg|thumb|right|''[[Tylecodon reticulatus]]'']]

==Pharmacology and toxicology==

''Tylecodon'' species are poisonous. Some of them are sufficiently hazardous to livestock to constitute an economic problem for stock farmers. Concerns also have been expressed on potential risks to collectors who handle the plants carelessly. The various species and even individual plants do however vary greatly in toxicity.<ref name= "WattPP">Watt, John Mitchell, Breyer-Brandwijk, Maria Gerdina: ''The Medicinal and Poisonous Plants of Southern and Eastern Africa'' 2nd ed Pub. E & S Livingstone 1962</ref>

The best-known active ingredients of ''Tylecodon'' species are [[bufadienolide]]s [[Biochemistry|biochemically]] related to [[toad venom]]s and [[bile acid]]s. In some species more than half a dozen such compounds have been identified.<ref name = vWvHvO>{{cite book |author1=van Wyk, Ben-Erik |author2=van Heerden, Fanie |author3=van Oudtshoorn, Bosch | title = Poisonous Plants of South Africa | publisher = Briza | location = Pretoria | year = 2002 | isbn = 978-1875093304}}</ref> As such they are nervous and muscle poisons that cause various cardiac symptoms. In livestock they cause various forms of the condition known as ''krimpsiekte'', meaning "contraction" or "shrinking" disease. The meat of poisoned animals is dangerous to dogs or humans that eat it.<ref name = vWvHvO/> However, it also is claimed that the meat is only dangerous to eat if it is raw or incompletely cooked, and that it may be eaten with relative safety if thoroughly cooked.<ref name= "WattPP"/> If this is correct, it is not clear why cooking should have such an effect, and accordingly readers should be cautious in relying on such claims.

Pollinators such as [[honey bee]]s visit the plants avidly during the flowering season, without recorded ill effects from the nectar or pollen.

==Status==
Currently the [[IUCN Red List]] lists only two species of ''Tylecodon'' as "''near threatened''" (NT), namely ''Tylecodon aridimontanus'' and ''Tylecodon aurusbergensis''.<ref>{{cite iucn |author=Craven, P. |author2=Loots, S. |date=2004 |title=''Tylecodon aridimontanus'' |volume=2004 |page=e.T46839A11084977 |doi=10.2305/IUCN.UK.2004.RLTS.T46839A11084977.en |access-date=12 November 2021}}</ref><ref>{{cite iucn |author=Loots, S. |author2=Craven, P. |date=2004 |title=''Tylecodon aurusbergensis'' |volume=2004 |page=e.T46840A11085219 |doi=10.2305/IUCN.UK.2004.RLTS.T46840A11085219.en |access-date=12 November 2021}}</ref> However, stock deaths have prompted farmers to treat the plants as weeds, to the extent that fears have been expressed for the future of some species.

==Cultivation==
Some species of ''Tylecodon'' are attractive or intriguing enough to be popular among succulent collectors. However, novices have been advised to take precautions against poisoning. For example, some experienced horticulturists wear gloves when handling the plants. Most species are easy to grow in well-drained soil in hot conditions in full sunlight, very sparingly watered, as is commonly recommended for succulents from arid regions.

==Species==
The genus ''Tylecodon'' includes the following species, but this list certainly is incomplete. For one thing, it does not contain any mention of subspecies, hybrids and the like. Also, inevitably, new species are described occasionally.

* ''[[Tylecodon albiflorus]]'' Bruyns<ref name="isbn1-874907-03-X">{{cite book |title=Plants of southern Africa: Names and distribution (Memoirs van die Botaniese Opname van Suid-Afrika) |publisher=National Botanical Institute |location=Pretoria |year=1993 |isbn=1-874907-03-X }}</ref>
* ''[[Tylecodon aridimontanus]]'', G. Will.
* ''[[Tylecodon atropurpureus]]'' Bruyns<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon aurusbergensis]]'', G. Will. & Van Jaarsv.
* ''[[Tylecodon bayeri]]'' E. J. Van Jaarsveld<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon buchholzianus]]'' (Schuldt & Stephens) Tölken FP 45: 1774.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon cacaliodes]]'' (L. f.) Tölken FP 7: 249.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon cacaliodes]]'' (L. f.) Tölken x T. paniculatus (L. f.) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon decipiens]]'' Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon ellaphieae]]'' E. J. Van Jaarsveld FP 50: 1983.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon faucium]]'' (V. Pölln.) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon fragilis]]'' (R. A. Dyer) Tölken FP 41: 1631.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon grandiflorus]]'' (Burm. f.) Tölken FP 27: 1046.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon hallii]]'' (Tölken) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon hirtifolius]]'' (W. f. Barker) Tölken FP 18: 690.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon kritzingeri]]'' E. J. Van Jaarsveld FP 51: 2006.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon leucothrix]]'' (C. A. Sm.) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon occultans]]'' (Tölken) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon paniculatus]]'' (L. f.) Tölken FP 29: 1142.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon pearsonii]]'' (Schonl.) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon pusillus]]'' Bruyns <ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon pygmaeus]]'' (W. f. Barker) Tölken FP 10: 396.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon racemosus]]'' (Harv.) Tölken FP 22: 848.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon reticulatus]]'' (L. f.) Tölken <ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon rubrovenosus]]'' (Dinter) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon schaeferianus]]'' (Dinter) Tölken FP 10: 394<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon similis]]'' (Tölken) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon singularis]]'' (R. A. Dyer) Tölken FP 41: 1606.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon stenocaulis]]'' Bruyns<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon striatus]]'' (P. C. Hutch.) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon suffultus]]'' Bruyns ex Tölken var. suffultus.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon sulphurous]]'' (Tölken) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon tenuis]]'' (Tölken) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon tomosus]]'' Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon tuberosus]]'' Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon ventricosus]]'' (Burm. f.) Tölken<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon viridiflorus]]'' (Tölken) Tölken FP 48: 1919.<ref name="isbn1-874907-03-X"/>
* ''[[Tylecodon wallichii]]'' (Harv.) Tölken subsp. wallichii<ref name="isbn1-874907-03-X"/>

==References==
{{Reflist|30em}}

== Bibliography ==
{{Refbegin}}
* {{cite journal |last1=Tölken |first1=H. |title=New taxa and new combinations in Cotyledon and allied genera |journal=[[Bothalia]] |date=15 December 1978 |volume=12 |issue=3 |pages=377–393 |doi=10.4102/abc.v12i3.1794 |url=https://www.researchgate.net/publication/283906995|doi-access=free }}
* {{cite journal |last1=Mort |first1=Mark E. |last2=Levsen |first2=Nicholas |last3=Randle |first3=Christopher P. |last4=Van Jaarsveld |first4=Ernst |last5=Palmer |first5=Annie |title=Phylogenetics and diversification of Cotyledon (Crassulaceae) inferred from nuclear and chloroplast DNA sequence data |journal=[[American Journal of Botany]] |date=July 2005 |volume=92 |issue=7 |pages=1170–1176 |doi=10.3732/ajb.92.7.1170|pmid=21646139 |ref={{harvid|Mort et al|2005}}}}
{{Refend}}

{{Commons category|Tylecodon}}{{Wikispecies}}

{{Taxonbar|from=Q1247898}}

[[Category:Tylecodon| ]]
[[Category:Crassulaceae genera]]
[[Category:Taxonomy articles created by Polbot]]

Tylecodon - Revision history

imported>OAbot: Open access bot: doi added to citation with #oabot.