Today I decided to repot a few Lithops, so I figured it’d be cool to show you what goes on below the face of Lithops. Lithops have quite a small permanent root system, pretty much just consisting of a stubby, woody taproot. The rest of the root system (which can be huge, usually totally filling the pot they’re in) consists of lots and lots of very fine feeder roots. These fine feeder roots are produced within 24 hours of the plant receiving water and usually die shortly after the root-zone dries out. Cacti do a similar thing, rapidly growing root tissue (particularly root hairs) when water is present and having parts of the roots die back with extended drought, but cacti tend to produce much thicker roots which take longer to die back in periods of drought.
Another interesting thing about Lithops you can see in the first picture is the transition from the coloured, non-photosynthetic top of the leaves to the actively photosynthetic, green lower portion of the leaves. The photosynthetic sides of the leaves are usually below ground for protection. The face of the plant is actually a window, which allows light into the body of the plant (filled with a transparent gel) where it can then be harnessed by the photosynthetic sides of the leaves. As the face isn’t photosynthetic, only the sides of the leaves need to obtain Carbon dioxide for photosynthesis, allowing the stomata to be concentrated on the sides of the leaves too. By doing so, the stomata are kept below ground, where it is cooler and so the plant loses less water when the stomata are open. Coupled with CAM (only opening stomata at night and metabolic differences), this allows Lithops (and other succulents which do this kind of thing) to use water extremely efficiently.
Anyway, these were all repotted today. The names of some of these are ridiculously long, so if anyone wants to know what a particular plant is, it’s probably best to message me. The first unpotted plant is a single-headed plant and the second is double-headed. The heads divide when the new leaves grow, after the old single-head reaches a certain size.