AIZOACEAE 



203 



Plate 50. 



Mesembrianthemum. 



A. M. edule L. 1. Flower. 2. Section of leaf. 3. Ripe fruit, divided crossways. 



B. M. acinaciforme L. Section of leaf. 



C. M. criniflorum Houtt. From Cape Flats. Rose-coloured variety. 



D. M. aureum L. From Worcester. 



Mesembrianthemum. 



The flowers of Mesembrianthemum, although showing a great range of 

 size, from a few millimetres to three inches in diameter, are of a very uniform 

 structure, varying chiefly in the relative size of the parts. The colours are 

 most brilliant, from the purest white to the deepest red, purple or yellow, in 



Fig. 92. Mesembrianthemum edule L., with Dimorphotheca pluvialis and Briza maxima. 

 Near Capetown. September. Photo. E. J. Steer 



all possible shades. The brilliancy is due to a comparatively simple feature of 

 their structure, every cell of the epidermis being a small optical apparatus, 

 resembling a combination of a concave mirror with a prism of which the base 

 (here the cuter side of the cell) is convex. A fuller explanation of the optical 

 phenomena involved is given under Nerine (Vol. iv, Plate 33), but while in 



