Pleiospilos nelii
Schwantes

Family : Mesembryanthemaceae/Aizoaceae (vygie family)
Common names
: split rocks (Eng.); kwaggavy(-gie) (Afr.)

Pleiospilos nelii is an intriguing little succulent and one of the best examples of mimicry.

Description
Pleiopilos nelii is a dwarf stemless succulent that closely resembles the stones in its natural area with its spotted appearance, shape and size. The subglobose (almost spherical) leaves are opposite, with a deep fissure in the centre, but joined at the base. In winter the pair of leaves splits open to make way for the new leaves. The leaves change from greyish green to reddish in the warm summer months. The 60 mm diameter, salmon or pinkish yellow flowers are borne in July to August. Once the flowers start to wither, their colour changes to orange. The flowers are solitary or up to four growing between the leaves. The fragrant flowers have a short pedicel and open in the mid-afternoon. The nine- to fifteen-locular, mostly eleven-locular, capsules open when wet and release the tiny seeds.

Subglobose leaves of Pleiopilos nelii

Conservation status
The current conservation status of Pleiospilos nelii is listed as Near Threatened. In the past the collection of this succulent, well sought-after for the horticultural trade, has caused a decline in the species. Currently the biggest threat is overgrazing and trampling by livestock.

Distribution and habitat
Kwaggavygies occur in sparse Karoo vegetation on the border between the Western and Eastern Cape. They usually occur in small populations or singly scattered over the veld. They occur in the semi-arid area that receives 150300 mm of rain per annum. Most of the rain falls in summer with occasional winter rain.

Pleiospilos neliiDerivation of name and historical aspects
Pleiospilos nelii was first described in 1930 in honour of Prof G.C. Nel. The genus name Pleiospilos is derived from the Greek words pleios (full) and spilos (spot), referring to the well-speckled leaves. There are currently only four species in this genus. Previously 38 species were recorded, but with the revision of the genus, three species were moved to a new genus, Tanquana, and the rest were considered different forms and subspecies of the widespread and variable Pleiospilos compactus. The best known species in this genus is Pleiospilos simulans which is better known as the liver plant.

Ecology
Pleiospilos nelii is pollinated by insects. The woody capsules are hygrochastic (open when wet) and the tiny seeds are splashed out of the capsule by the heavy raindrops. The capsule closes when dry, releasing only some of the seeds each time, to ensure that there are favourable conditions for germination. Pleiospilos species are occasionally browsed by livestock, and having them in the veld is a good indication of a healthy veld. To hide from the animals they grow flat on the ground blending in with the background of their habitat.

Uses and cultural aspects
The only use for this plant is in the horticultural trade. It is recorded that another species in the genus, P. bolusii is dried, powdered and used as a snuff.

Growing Pleiospilos nelii

Pleiospilos neliiThe kwaggavygie does best in a greenhouse or on a sunny windowsill. In arid regions, especially summer rainfall areas, it can also be planted outside on a rockery. It should be planted in well drained soil, and keep in mind that this plant has a relatively long taproot. Pleiospilos nelii should get little water in winter and in summer. Unlike other Pleiospilos species, P. nelii will not flower if it is kept dry in winter. When watering, rather drench the soil and allow the soil to dry out for 23 weeks before watering again. The new pair of leaves starts growing in winter. The plant uses the moisture from the old leaves to create the new ones. If the old leaves are still present in summer, the plant might be getting too much water.

Pleiospilos nelii can easily be grown from seeds. Sow seeds in the summer months. To improve the success of germination place the seeds in a small container with luke warm water and leave for 24 hours. This will soften the hard outer layer of the seed. Sow the seeds in a sandy medium. Cover the seeds with a 1 mm thick layer of fine sand; make sure that the seeds are not covered too thickly. The layer of sand prevents the tiny seeds from washing away, and it is best to water with a very fine spray. Keep them damp until they start to germinate in about seven days. Once the seedlings start growing, slowly reduce the amount of water given. The seedlings grow very slowly and should be replanted once they have reached a size of about 10 mm.

The kwaggavygie is susceptible to red spider mites that scar the leaf surface with brown markings. Treat with horticultural oil, such as oleum, in a solution of 20 ml oleum to one litre of water.

References and further reading

  • Barkhuizen, B.P. 1978. Succulents of Southern Africa. Purnell & Sons Publishers, Cape Town.
  • Court, D. 2000. Succulent flora of Southern Africa. Revised edition. A.A. Balkema. Rotterdam, Netherlands.
  • Jackson,W.P.U. 1990. Origin and meanings of names of South African plant genera. UCT, Rondebosch.
  • Raimondo, D., Von Staden, L. et al. 2009. Red List of South African plants. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
  • Schwantes, G. 1957. Flowering stones and mid-day flowers. Ernest Benn Limited, London.
  • Smith, G.F., Chesselet, P. et al. 1998. Mesembs of the World. Briza, Pretoria.
  • Van Wyk, B.-E. & Gericke, N. 2000. People's plants. Briza, Pretoria.

 

 

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Karoo Desert National Botanical Garden
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