• Mimicry among Plants. 101 



Another species of Mesembrianthemum seems to achieve the same 

 object in a different way. It forms fleshy cushions on the ground 

 up to 10 inches in diameter. These cushions consist of a large 

 number of tooth-shaped fleshy leaves, which are snow white. All 

 that is nothing unusual in the karroo, where plants with pure white 

 leaves are not uncommon. It surprised me, however, that this 

 plant occurred only where the ground was covered with fragments 

 of white quartz. I found several patches of the plant, but only on 

 these fields of white quartz. Of course there were many such 

 localities without this plant, for white quartzites are of common 

 occurrence in the Laingsburg and Ladismith districts. 



A similar observation has been made in connection with another 

 plant by myself as well as by a friend of mine. This is Anacamp- 

 seros papyracca E. Mey., a little succulent of the karroo which is 

 pure white owing to the large papery stipules which cover the tiny 

 leaves. I have seen hundreds of these plantlets in the Laingsburg, 

 Ladismith, and Prince Albert districts, but only on such fields of 

 white quartz — with one exception, and that was a specimen growing 

 in clayey soil. But, and this fact is very significant, this plant stood 

 in a group of Apicra deltoidea Bak., which has leaves that are as 

 rigid and sharp-pointed as if they were cut out of a piece of stout 

 metal. 



I do not consider the peculiar occurrence of this Anacampseros 

 and the last-mentioned species of Mesembrianthemum as mimicry, 

 for the white hairs on the leaves of the Mesembrianthemum and the 

 papery stipules of the Anacampseros serve in the first instance 

 another function. But the whiteness of the plants has probably 

 allowed those individuals which occurred in similar surroundings 

 to escape the depredations of animals, particularly of those which 

 feed at night-time like the hares. It is interesting to note that 

 some natives call this Anacampseros " haasjes kost," probably 

 indicating that hares are fond of the plant. 



In conclusion, I should like to sum up my views on this question, 

 as far as the South African plants are concerned, as follows : — 



1. There are some plants which seem to occur only, or at least 

 mostly, on fields of white quartz, where they are not easily noticed, 

 particularly not at night-time, owing to their own white colour. It 

 is probable that this limited occurrence in these districts is due 

 to the destruction of those individuals which sprang up in other 

 localities where their whiteness easily betrayed them to the night- 

 feeding animals. Examples are Anacampseros papyracea and a 

 species of Mesembrianthemum. 



2. There are some species of Mesembrianthemum which are so 



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