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Scientific Name | Conophytum calculus (A.Berger) N.E.Br. subsp. calculus |
Higher Classification | Dicotyledons |
Family | AIZOACEAE |
Synonyms | Conophytum calculus (A.Berger) N.E.Br. var. komkansicum (L.Bolus) Rawé, Conophytum komkansicum L.Bolus, Mesembryanthemum calculus A.Berger |
National Status |
Status and Criteria | Critically Endangered A4d |
Assessment Date | 2021/11/16 |
Assessor(s) | A.J. Young, P.G. Desmet, I. Ebrahim, D. Guo, A. Harrower, L. Jabar, L. Knoetze, C. Rodgerson, P.C.V. Van Wyk & N.N. Mhlongo |
Justification | This succulent is endemic to the Western Cape province of South Africa with an extent of occurrence (EOO) of 2,629 km² and area of occupancy (AOO) of 156 km². The population is experiencing substantial decline due to the illegal ornamental succulent plant trade, with collection likely to increase as there has been a dramatic increase in the number of species and volume of plants targeted since 2019. The continued threat of illegal collection is therefore regarded as very high for this particular taxon and a decline of up to 90% of the population is likely within the next ten years. Climate change is also impacting the population although there is uncertainty of the response given the expected resilience of this taxon. It therefore qualifies as Critically Endangered under criterion A4. |
Distribution |
Endemism | South African endemic |
Provincial distribution | Western Cape |
Range | This taxon is endemic to a small part of the Western Cape province of South Africa. |
Habitat and Ecology |
Major system | Terrestrial |
Major habitats | Knersvlakte Quartz Vygieveld, Southern Namaqualand Quartzite Klipkoppe Shrubland, Namaqualand Riviere |
Description | It is endemic to the Knersvlakte bioregion of the Succulent Karoo biome. Plants are found on areas of quartz stones and pebbles with the plants usually fully exposed to the sun. The plants experience sporadic winter rainfall. This taxon has a generation length of 30 years. It is expected to be sensitive to the impacts of climate change as it does not disperse and while adapted to arid conditions, is dependent on limited seasonal rainfall. Species in the genus are sensitive to long periods of drought. Drought related mortality has been observed for other closely related taxa within the genus. |
Threats |
| It is currently threatened by illegal collection for the international trade in ornamental succulents. This is likely to increase in future as there has been a dramatic increase in the number of species and volume of plants targeted since 2019.
Anthropogenic climate change is a long-term threat to this taxon. Climate models for the likely emission scenarios where emissions stay at present day levels (RCP 2.6) (Hausfather and Peters 2020) and worst case scenarios where emissions continue to increase during the 21st century (RCP 8.5) indicate that there will be a loss of suitable bioclimatic envelope of between 40% and 85% by 2080. However, as this taxon possesses certain morphological traits likely to afford resilience to xerophytic conditions and is found across several vegetation units it is expected to have a level of resilience to climate change and the expected population loss is reduced by 20% to 20%. Species in this genus have limited dispersal ability and migration to suitable habitats elsewhere is regarded as highly unlikely. |
Population |
There is no formal estimate of population size for this taxon, but is estimated to be in excess of 20,000 mature individuals. The population is declining as a result of illegal collection of wild specimens to supply the ornamental succulent plant trade. This taxon has been highly sought after by collectors with several thousand plants removed illegally since 2019. A total of 11,600 plants have been confiscated from plant poachers with many others likely not to have been intercepted and to have found their way to China.
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Population trend | Decreasing |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | | Conophytum calculus (A.Berger) N.E.Br. subsp. calculus | VU A4bd | 2020.1 | | Conophytum calculus (A.Berger) N.E.Br. subsp. calculus | Least Concern | Raimondo et al. (2009) | |
Bibliography |
Hammer, S. 2002. Dumpling and his wife: New view of the genus Conophytum. EAE Creative Colour, Norwich.
Hammer, S.A. 1993. The genus Conophytum: A conograph. Succulent Plant Publications, Pretoria.
Hausfather, Z. and Peters, G.P. 2020. Emissions - the 'business as usual' story is misleading. Nature 577(618-620).
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Citation |
| Young, A.J., Desmet, P.G., Ebrahim, I., Guo, D., Harrower, A., Jabar, L., Knoetze, L., Rodgerson, C., Van Wyk, P.C.V. & Mhlongo, N.N. 2021. Conophytum calculus (A.Berger) N.E.Br. subsp. calculus. National Assessment: Red List of South African Plants version . Accessed on 2024/12/03 |
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