2o8 AIZOACEAE 



The flowers are visited by a butterfly, the cosmopolitan I anessa Cardui 

 (the painted lady), which to our surprise was fairly numerous in the desert 



at that season of the Near. 



Mesembrianthcmum calcareum. This species affords another striking example 

 of protective mimicry among plants. The leaves form a dense rosette, and 

 their surface, as far as exposed, is covered with irregular excrescences that look 

 exactly like the whitish fragments of lime-tufa between which the plant grows. 

 No artist could imitate the surface texture and colouring of the limestone more 

 accurately than nature has done in this case*. It so happened on one occasion, 

 that we had the good fortune to find this species and M. Hookeri on the same 

 day, hut the one only where there was nothing but limestone and the other 

 only among the brownish soil and gravel of an ironstone belt, the similarity 

 to their surroundings being perfect in both cases. 



M. calcareum has been found by us in two localities, viz. at Alexanders- 

 fontein near Kimberley and on the Kaap plateau near Griquatown, in both 

 cases tightly wedged in between the chips of lime-tufa and quite flush with the 

 surface. It has also been received from Hanover (C. C.) by Dr Schonland of 

 Grahamstown ; hence it appears to be widely distributed. It is apparently 

 the only plant in South Africa with such a rugged leaf-surface; in Central 

 America a few species of Anhalonium occur, resembling it very much in this 

 respect, e.g. A. fissuratum (Cactaceae). 



* The lithographer, in his endeavour to show up the plants more distinctly than they 

 appeared in the original painting, has gi\en the stones surrounding them a purplish tone. 

 In nature the plants match the colour ot" the limestone exactly, being equally white and 

 grey with brown dust here and there. 



