Lithops - Au Cactus Francophone

Figure 5 . lithops salicola l. bol.
In situ. in habitat. Lückhoff
Luckhoff > Lückhoff
which contains the window and then holding it up so that light falls through
the window, or the window is quite transparent since very little of the in
cident light is cut off. The window is green or variously coloured. L. optica
var. rubra is in a class by itself for the top surface of this plant is of a uni
form reddish purple colour. This plant occurs amongst the ordinary L. optica,
which possesses a fairly transparent greenish window. Unfortunately no seed
has been available so further study of this peculiar and interesting variety has
not been possible.
As regards the nature of the window four types can be distin
guished:— (i) turbiniformis‑group, where the window is apparently opaque as
it lets through very little light (L. turbiniformis, L. Ruschiorum, L. gracilide‑
lineata), (ii) fulviceps‑group, where the greater part of the window is appar
ently opaque, but embedded in this opaque covering a number of prominent,
transparent papillae (miniature windows) are observed (L. fulviceps), (iii)
olivacea‑group, where the main body of the window is quite transparent (L.
olivacea, L. optica, L. salicola), (iv) pseudotruncatella‑group, where the window
possesses an opaque or semi opaque covering which is perforated by a large
number of round, pellucid spots (miniature windows) sunk into the tissue
and level with it. It will be noted that in both the fulviceps and pseudo‑
truncatella types miniature windows are present, but in the first named these
dots are convex and stand out above the level of the leaf, when the latter is
turgid, while in the pseudotruncatella type the miniature windows are flush
with the surface. In some eases, L. Schwantesii, for example, these pellucid
dots are of a bluish green colour.
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