Limestone sugarbush (Protea obtusifolia)

Description

What’s the World’s Favourite Species?

Limestone sugarbush fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Limestone sugarbush description

The limestone sugarbush belongs to the Proteaceae family, a hugely diverse group of plants well-known in South Africa for their bright, showy flower heads ⁽³⁾. This species is no exception, producing large, cone-shaped flower heads, up 12 centimetres long ⁽⁴⁾, which are formed from clusters of numerous tiny flowers ⁽⁵⁾. The flower heads are encircled by modified leaves, which vary from white to vivid shades of red. The leaves on the rest of the plant are dark green, elongated and leathery, and have a strong upward curve ⁽⁴⁾. Reaching around two to four metres in height, the limestone sugarbush usually takes the form of a large, roundish shrub, but some specimens may be more tree-like, developing spreading branches and a trunk of up to 60 centimetres in diameter ^{(4) (6)}.

Limestone sugarbush biology

A number of bird species are attracted to the brightly coloured flower heads produced by the limestone sugarbush during the cool, wet winter months of June and July ^{(7) (9)}. As the birds feed on the flowers’ abundant nectar, their feathers become coated in pollen, which is then transferred to the flower heads of other plants visited, thereby facilitating this species’ pollination ⁽⁹⁾.

Like many fynbos species, the reproduction of the limestone sugarbush is absolutely dependent on fire. After pollination, the multiple flowers making up the flower heads develop into small, hard nuts, each containing a single seed, which remain on the plant until the occurrence of a wild fire ^{(5) (7)}. Wild fires, which are regularly triggered in the hot, dry conditions of summer and autumn, spread rapidly through fynbos and, although they destroy the adult limestone sugarbush plants, they release the seeds and promote their germination, thereby establishing a new generation of plants ^{(3) (7)}.

Limestone sugarbush range

The limestone sugarbush is only found on the Agulhas Plain, on the southern coast of the Western Cape Province of South Africa ^{(4) (7) (8)}.

Limestone sugarbush habitat

The limestone sugarbush is a component of fynbos, a plant community unique to the Cape Floristic Region. This species has specific habitat requirements and only grows in the alkaline soil found in potholes and depressions in the low limestone hills and flats of the Agulhas Plain ^{(7) (8)}.

Limestone sugarbush status

Classified as Near Threatened (NT) on the Interim Red Data List of South African Plant Taxa ⁽²⁾.

Limestone sugarbush threats

Unfortunately, many parts of the Agulhas Plain have been degraded by the construction of coastal resorts and conversion to agriculture. In addition, introduced species such as Australian wattles have overtaken much of the native vegetation, outcompeting native plants and exhausting underground water sources ⁽¹⁰⁾. With its range restricted to a single, relatively small region, the limestone sugarbush is particularly vulnerable to these ongoing threats.

Limestone sugarbush conservation

In 1999, the Agulhas National Park was established and, although still in development, it represents a significant conservation achievement, protecting large areas of limestone fynbos and, thereby, preserving the region’s unique species, including the spectacular limestone sugarbush ^{(8) (11)}.

Find out more

To learn more about the Agulhas National Park visit:

• South African National Parks:
  www.sanparks.org/parks/agulhas

Authentication

Glossary

Cape Floristic Region

An area occupying about 90,000 square kilometres in South Africa that contains an incredibly high diversity of plant species (around 8,700 species), of which 68 percent are found no where else.

Fynbos

The natural shrubland vegetation occurring in the southwestern and southern Cape of South Africa, holding the greatest diversity of plant species in the world. Fynbos is characterised by tall shrubs with large leaves, heath-like shrubs, wiry reed-like plants, and bulbous herbs.

Germination

The beginning of growth, usually following a period of dormancy and in response to favourable conditions. For example, the sprouting of a seedling from a seed.

Pollination

The transfer of pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.

References

1. IUCN Red List (November, 2008)
   http://iucnredlist.org
2. Threatened Species Programme. (2007) Interim Red Data List of South African Plant Taxa. South African National Biodiversity Institute, Pretoria, South Africa.
3. Cowling, R. and Richardson, D. (1995) Fynbos: South Africa’s Unique Floral Kingdom. Fernwood Press, Vlaeberg, South Africa.
4. Van Wyk, B. and Van Wyk, P. (1997) Field Guide to Trees of Southern Africa. Struik, Cape Town.
5. Protea Atlas Project (November, 2008)
   http://protea.worldonline.co.za/whatpro.htm
6. Rebelo, T. (2001) Proteas: A Field Guide to the Proteas of Southern Africa. Fernwood Press, Vlaeberg, South Africa.
7. Protea Atlas Project (November, 2008)
   http://protea.worldonline.co.za/sugar9.htm
8. Wolfart, S. (2006) The Southern Tip of Africa. New Africa Books, Cape Town.
9. Protea Atlas Project (November, 2008)
   http://protea.worldonline.co.za/pollinat.htm
10. Heydenrych, B.J., Cowling, R.M. and Lombard, A.T. (1999) Strategic conservation interventions in a region of high biodiversity and high vulnerability: a case study from the Agulhas Plain at the southern tip of Africa. Oryx, 33: 256 - 269.
11. South African National Parks (November, 2008)
    http://www.sanparks.org/parks/agulhas