Large-leaf sugarbush
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Proteales
Family: Proteaceae
Genus: Protea
Species:
P. convexa
Binomial name
Protea convexa
Protea convexa distribution
  Extant (resident)

Protea convexa, also known as large-leaf sugarbush,[3][4][5] is a rare flowering shrub in the genus Protea of the family Proteaceae,[3][4][6] which is endemic to the southwestern Cape Region of South Africa.[3][7]

Taxonomy

The first person who is known to have collected Protea convexa was the German explorer Rudolf Marloth on plains near Matjiesfontein in September 1903. Marloth's collection of a pressed specimen (#3209)[8][9] was sent to and arrived at the Kew Herbarium in 1904, where it has been housed ever since.[9] Based on this specimen, in 1910 the South African botanist Edwin Percy Phillips then described it as a new species.[2][8] Phillips did not designate holotypes in his paper,[8] but in 1960 the South African botanist Hedley Brian Rycroft designated Marloth's specimen as such.[9] The specific epithet refers to the shape of the receptacle, the bottom of the flower head.[8]

Description

This is a flat, prostrate shrub,[5] although it has been said to grow up to 10 feet (3.0 m) high.[10] On average, individual plants have a generation length of about 20 years.[3] The leaves are very broad and large for a Protea,[4] 5–9 inches (13–23 cm) in length and 2–3.5 inches (5.1–8.9 cm) broad at the widest point.[10] The leaves are glaucous,[8][9][10] glabrous and prominently veined.[10] The flower heads are squat and compressed in shape,[9] with a convex, hemispherical receptacle (the bottom of the structure).[8] It is monoecious, both sexes occur in each flower. The seeds are stored in capsules, themselves stored in the dried old flower head.[5]

Similar species

In his initial diagnosis, Phillips found it to be most similar to Protea acaulos, or at least what he called P. acaulis var. obovata, differing in the shape of the receptacle. It also has larger, glaucous leaves and a larger flower head.[8]

Distribution

This species is endemic to the Western Cape province of South Africa.[3][7] It is specifically found in the northern Cederberg,[3] Witteberg,[3][4][5] Klein Swartberg,[3][5] Elandsberg, and Tra-Tra mountain ranges.[5] It can be found in the mountains above the Klein Karoo in the background of the village of Matjiesfontein.[3][4][9]

Ecology

The plant grows on the northern slopes of arid, rocky kloofs (dry ravines) at altitudes of 1,100 to 1,500 metres.[3][5] It exclusively grows in a fynbos habitat in the wild, in substrates derived from either sandstone or quartzite.[3]

The adult specimens of this protea are killed when they are caught in the wildfires which periodically pass through the native habitat, but the seeds can survive such events.[3][5] Its flowers bloom in Spring,[4] from August to November, with the peak in October. Pollination occurs through the visits of either rats, mice,[5] birds[3][5] or insects.[3] The seeds are stored in the fruit after becoming ripe, and the fruit are themselves stored in the old, dried, fire-resistant inflorescences, which are persistently retained on the plant after senescence. The inflorescences open one to two years after flowering after fires have passed through the land. When released from their capsules, the seeds are eventually dispersed by means of the wind.[3][5]

Conservation

Protea convexa was already assessed as 'rare' in 1980, a conservation status which was given again in 1996 by the South African National Biodiversity Institute (SANBI) in the first Red List of South African Plants.[3] It was considered rare and known from only a few populations in the 1990s.[5] In their 2006 assessment for the Red List, SANBI considered the conservation status to be 'critically endangered', this was repeated again in the 2009 assessment.[3]

The plant is mostly thought to be threatened by the expansion of rooibos tea farms in its habitat, as well as the effects of climate change. It is susceptible to drought, plants can die in such circumstances. Other potential threats identified were invasive plants, natural disasters and pollution.[3]

In 2005 Bomhard et al. predicted, based on their reading of models projecting the effects of climate change, that more than 80% of the population of the time would be extirpated by 2020, which qualified the species for upgrading its conservation status from 'lower risk' to 'critically endangered'.[11] In the 2006 assessment, SANBI, "based on the opinion of experts", moved up the date when the species would be reduced by more than 80% to 2025. The total population numbers were thought to be decreasing in 2006.[3]

References

  1. ↑ Rebelo, A.G.; Raimondo, D.; Helme, N.A.; Schutte-Vlok, A.L. (2020). "Protea convexa". IUCN Red List of Threatened Species. 2020: e.T113209044A185581492. doi:10.2305/IUCN.UK.2020-3.RLTS.T113209044A185581492.en. Retrieved 18 November 2021.
  2. 1 2 "Protea convexa". International Plant Names Index. The Royal Botanic Gardens, Kew, Harvard University Herbaria & Libraries and Australian National Botanic Gardens. Retrieved 13 August 2020.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Rebelo, A.G.; Mtshali, H.; von Staden, L. (10 November 2006). "Large-leaf Sugarbush". Red List of South African Plants. version 2020.1. South African National Biodiversity Institute. Retrieved 13 August 2020.
  4. 1 2 3 4 5 6 "Protea convexa (Large-leaf sugarbush)". Biodiversity Explorer. Iziko - Museums of South Africa. Retrieved 13 August 2020.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 "Western Ground Sugarbushes - Proteas". Protea Atlas Project Website. 11 March 1998. Retrieved 13 August 2020.
  6. ↑ "Protea convexa in Global Plants on JSTOR". plants.jstor.org. Retrieved 2020-07-19.
  7. 1 2 "Protea convexa E.Phillips". Plants of the World Online. Kew Science. 2017. Retrieved 13 August 2020.
  8. 1 2 3 4 5 6 7 Phillips, Edwin Percy (1910). "Diagnoses Africanae: XXXVII". Bulletin of Miscellaneous Information, Royal Gardens, Kew (in Latin). 1910 (7): 235, 236. Retrieved 13 August 2020.
  9. 1 2 3 4 5 6 "Specimen Details K000423584". Kew Herbarium Catalogue. Board of Trustees of the Royal Botanic Gardens, Kew. Retrieved 24 August 2020.
  10. 1 2 3 4 Stapf, Otto; Phillips, Edwin Percy (January 1912). "CXVII. Proteaceæ". In Thiselton-Dyer, William Turner (ed.). Flora Capensis; being a systematic description of the plants of the Cape Colony, Caffraria & Port Natal. 5. Vol. 1. London: Lovell Reeve & Co. pp. 584, 585. doi:10.5962/bhl.title.821.
  11. ↑ Bomhard, Bastian; Richardson, David M.; Donaldson, John S.; Hughes, Greg O.; Midgley, Guy F.; Raimondo, Domitilla C.; Rebelo, Anthony G.; Rouget, Mathieu; Thuiller, Wilfried (25 July 2005). "Potential impacts of future land use and climate change on the Red List status of the Proteaceae in the Cape Floristic Region, South Africa". Global Change Biology. 11 (9): 1452–1468. Bibcode:2005GCBio..11.1452B. doi:10.1111/j.1365-2486.2005.00997.x. hdl:10019.1/116833. Retrieved 24 August 2020.
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