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Photo 1Lithops lesliei subsp. lesliei in flower (Photo DP van Rensburg)

Plant adaptations are fascinating and intriguing.  A very advanced and interesting adaption is mimicry.  Mimicry can happen in different forms, in certain flowering plants, especially orchids, it can imitate insect pollinators, and some plants have flowers with a scent similar to rotting flesh.  Others, like the mimicry succulents (for example Lithops lesliei, Photo 1), have adapted to merge perfectly with the habitat in which they grow (Photo 2).

Photo 2:  Try to spot the seven Lithops plants (Photo E van Rensburg)

Mimicry in plants is the result of natural selection.  Over long periods of time these plants have adapted to blend with the surrounding soil and stone environments.  Some plants are so well camouflaged, they resemble the shape, size, colour and even the texture of the environment they grow in, effectively making them very difficult to see and enhancing their chances of survival.  Only when you are searching for these mimicry succulents will you come to understand how well they blend in with their background.  Many stories have been told by botanists about trying to find these plants, even though they knew the precise localities. They still had to search small areas on their hands and knees trying to find the plants.  Then, once they have spotted the first plant, the stones come to life where the botanists have searched blindly a few moments before.  And just when you thought these plants cannot have any more surprises up their ‘leaves’, bright yellow flowers emerge for everyone to see (Photo 3 & 4)!

Photo 3Lithops lesliei subsp. lesliei in flower (Photo DP van Rensburg)

Photo 4Nananthus cf broomii in flower (Photo E van Rensburg)

These remarkable succulents are mostly associated with the dry, arid regions of the Karoo, Namaqualand and Namibia and are often overlooked in the Free State.  If you have time to search between the calcrete pebbles of the Free State (Photo 5) you will be amazed to find different mimicry species like Nananthus, Titanopsis and Lithops.

Photo 5: Nananthus locality in the Free State (Photo E van Rensburg)

The small and cryptic Nananthus or brakvygie is often overlooked, probably because the plants are so well camouflaged and not as well-known as other species (Photo 6).  These plants have thick rootstocks (Photo 7), maintaining most of their storage underground, and boat-shaped leaves with white dots on the leaf surfaces.

Photo 6Nananthus cf broomii in the field (Photo E van Rensburg)

Photo 7:  Thick rootstock of Nananthus (Photo E van Rensburg)

Titanopsis calcarea or more commonly known as skilpadvoetjies (little tortoise feet) is a well-known mimicry plant.  The grey, rough, concrete-like leaves of Titanopsis resemble their rugged and gritty calcrete habitat perfectly (Photo 8 & 9).

Photo 8Titanopsis calcarea or skilpadvoetjies (Photo PC Zietsman)

Photo 9Titanopsis calcarea in its calcrete habitat (Photo DP van Rensburg)

Lithops, or beeskloutjie (cattle hoof), is the genus with the best developed stone mimicry: The entire plant resembles a stone (Photo 10).  It is almost impossible to spot a Lithops, especially during the dry season, when they shrivel and might be lightly covered with sand – thus safely concealed from predators and protected from the harsh sun for many months. The first Lithops collector, William John Burchell, wrote: ‘…. in colour and appearance [it] bore the closest resemblance to the stones, between which it was growing.’

Photo 10Lithops lesliei subsp. lesliei, a stone plant (Photo DP van Rensburg)

If one day you are lucky enough to come across these special plants in the field, stand (kneel) in awe and let them be, over centuries they worked extremely hard to become masters of disguise!

References

Barrett, S.C.H. 1987. Mimicry in Plants. Scientific American 257: 76-85.

Baynes, E.S.A. 1961. Mimicry Mesembryanthemums. National Cactus and Succulent Journal 16: 63-65.

Byrd, R.K. 1946. ‘Living stones’ Marvels of Mimicry.  Protection by colour and form. National Cactus and Succulent Journal 1: 44-45.

Cole, D.T. 1988. Lithops: Flowering stones. Acorn Books.

Court, D. 2010. Succulent flora of Southern Africa. Revised edition. Struik Nature.

Hammer, S.A. 2013. Mesembs: The Titanopsis Group. Little Sphaeroid Press.

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