Lithops - Au Cactus Francophone

perience, namely that, although one can determine the general nature of the
colour, such as yellow for example, there are so many shades of this colour
that when one wants to describe a specific shade the difficulty starts. The top
surface is often not uniform in colour as for example in L. pseudotruncatella.
Furthermore small areas of the upper surface often differ from one another,
as in L. karasmontana, thus while the description may be true for one part
of the top it is not correct for a part a few millimetres away.
As the leaves become older, the differences of the various parts become
accentuated. When plants are removed from their natural habitat and grown
in Europe and in the moister parts of South Africa the top tends to lose its
brilliance. The plant also under such conditions protrudes above the ground,
becomes more concave, and assumes a greener tint than material fresh from
the field.
A representative of this genus which thrives in a part of the country
(Bethlehem, Pretoria) with a fairly heavy rainfall is L. Lesliei. L. terricolor
though occasionally found near Port Elizabeth, which has a fairly regular and
heavy rainfall, is characteristic of the driest parts of the Cape Province (Ceres,
Karroo, Laingsburg) with about two inches per year.
There is sometimes a marked difference between the colouration of
the depressions and the ridges of the rugose species such as L. karasmontana,
L. gracilidelineata. The network, which is sometimes a prominent feature of
the top surface, also shows a great deal of variation, not only in the way it
anastomises but also in its colouration. An extreme case is that of L. pseu‑
dotruncatella and L. verruculosa. The case of L. Vallis‑Mariae should also be
mentioned. In thus particular plant, the surface which appears uniform to
the naked eve consists in reality of a large number of ridges with vermiform
convolutions, giving the idea of sintered limestone.
In determining a species of Lithops a careful and close study must be
made of the markings, especially those on the depressions. L. Erniana has
a darkly coloured depression, but at the end of this depression one notices
short brown lines with a buff border. These lines stand at right angles to the
main depression. Red dots or short lines mark the intersection of the slight
depressions of L. chrysocephala.
Species with red dots or warts fall into two distinct groups: (i) those
like L. Dinteri, L. Dorotheae and L. insularis, where the red dots are embedded
in the tissue and are level with it, and (ii) L. Inae, where the red shiny dots
stand up above the surface of the leaf. In the first group the cell walls are
coloured red, whereas in L. Inae the cell cavities contain the liquid anthocyan.
10
WINDOW
As already pointed out the top surface of the leaf is apparently opaque,
although it lets light through as can be easily proved by cutting the top off,