Taxonomy
Scientific Name
Aponogeton angustifolius Aiton
Higher Classification
Monocotyledons
Family
APONOGETONACEAE
Synonyms
Aponogeton crinifolium Lehm. ex Schltdl.
National Status
Status and Criteria
Near Threatened B1ab(iii)+2ab(iii)
Assessment Date
2019/11/06
Assessor(s)
H. Mtshali, E. Sieben, J.A. Day & D. Raimondo
Justification
Aponogeton angustifolius has a limited distribution range, with an extent of occurrence of 6 100-6 249 km². It is localized to seasonal streams and wetlands, and therefore also has a small area of occupancy of 104-120 km². In spite of severe, ongoing habitat loss and degradation, recent field observations indicate that it is still relatively common, persisting at at least 17 locations. It however continues to decline across its range, and therefore it nearly meets the criteria thresholds for Vulnerable under criterion B.
Distribution
Endemism
South African endemic
Provincial distribution
Western Cape
Range
This species is endemic to the Western Cape, where it occurs from Gouda to Worcester and the Cape Flats.
Habitat and Ecology
Major system
Freshwater
Major habitats
Cape Flats Dune Strandveld, Swartland Shale Renosterveld, Peninsula Shale Renosterveld, Swartland Granite Renosterveld, Breede Shale Fynbos, Boland Granite Fynbos, Cape Flats Sand Fynbos, Atlantis Sand Fynbos, Lourensford Alluvium Fynbos, Swartland Alluvium Fynbos, Breede Alluvium Fynbos
Description
It occurs in water up to 1 m deep in sandy lake shores that dry out in summer, shallow pools or slowly flowing rivers.
Threats
It has declined on the Cape Peninsula and Cape Flats, as well as around Stellenbosch due to habitat loss to urban expansion. Urban expansion remains a threat to unprotected wetlands on the Cape Flats. In remaining protected wetlands on the Cape Flats, its habitat has been degraded due to disruptions of water flow dynamics due to surrounding urban developments, which changed many areas from seasonally waterlogged to permanently inundated. Severe pollution is also causing further habitat degradation. In the Swartland and Breede River Valley, much of its habitat has been lost or disturbed due to expanding crop cultivation. Remaining subpopulations occur on isolated fragments, where they are impacted by water pollution from agricultural runoff. The habitat at most remaining localities is also densely infested with alien invasive grasses and wattles, but this species appears to persist even in heavily invaded areas.
Population

Recent field observations recorded at least 15 remaining subpopulations. On the Cape Flats and in the Swartland, subpopulations are small and isolated, with most subpopulations consisting of less than 300 individuals, and most of these are threatened by severe, ongoing habitat degradation. The largest remaining subpopulation is in the Breede River Valley between Wolseley and the Brandvlei Dam near Worcester, where more than 1000 plants occur. It is now locally extinct on the northern Cape Peninsula, where its habitat was lost to urban expansion. It is not certain whether it still persists in several large wetlands near the False Bay coast such as Rondevlei, Seekoeivlei and Princess Vlei - it was last recorded in this area in the 1980s. One subpopulation was lost to construction of university residences in Stellenbosch in the early 2000s. Continuing population decline is inferred from ongoing habitat loss and degradation, but it is not possible to quantify population reduction over three generations.


Population trend
Decreasing
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Aponogeton angustifolius AitonVU A2c; B1ab(iii)Raimondo et al. (2009)
Bibliography

Cook, C.D.K. 2004. Aquatic and wetland plants of southern Africa. Backhuys Publishers, Leiden, The Netherlands.


Goldblatt, P. and Manning, J.C. 2000. Cape Plants: A conspectus of the Cape Flora of South Africa. Strelitzia 9. National Botanical Institute, Cape Town.


Manning, J.C. and Goldblatt, P. 2012. Plants of the Greater Cape Floristic Region 1: The Core Cape Flora. Strelitzia 29. South African National Biodiversity Institute, Pretoria.


Raimondo, D., von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. and Manyama, P.A. 2009. Red List of South African Plants. Strelitzia 25. South African National Biodiversity Institute, Pretoria.


Sieben, E.J.J. 2009. The status and distribution of vascular plants (Magnoliophyta, Lycophyta, Pteridophyta). In: W.R.T. Darwall, K.G. Smith, D. Tweddle and P. Skelton (eds.), The status and distribution of freshwater biodiversity in southern Africa (pp. 83-98), IUCN and SAIAB, Gland, Switzerland and Grahamstown, South Africa.


Van Bruggen, H.W.E. 1985. Monograph of the genus Aponogeton (Aponogetonaceae). Bibliotheca Botanica 137:1-76.


Citation
Mtshali, H., Sieben, E., Day, J.A. & Raimondo, D. 2019. Aponogeton angustifolius Aiton. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2020/10/25

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Distribution map

© G. Laidler

© N.A. Helme

© I. Ebrahim

© I. Ebrahim


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