Lithops is a genus of succulent plants originating in Southern Africa of the family Aizoaceae. Lithops in latin roughly translates to “stone face” or “stone-like in appearance”.
Their most well-known common name is ‘Living Stone.’ Each species of lithops has developed unique colorations and patterns to disguise itself among the shale, quartz, and feldspar on which they grow. In the wild, Lithops grow with the tops of their leaves nearly flush with the surface of the ground. This effect of mimicry gives Lithops the appearance of just another stone or pebble on the ground.
Lithops is unique among other plants in that it is composed wholly of two symmetrical leaves and a root system. Lithops only possess one pair of leaves, although some rare mutations exist that display three leaves per set. The tops of the leaves of lithops are known as “windows.” Although they may not seem so at a glance, the skin of lithops leaves is thin and varies in translucency. Closer examination of a lithops pattern may reveal dots in the design to actually be clear windows. Located below these widows in the very bottom of the leaf structure is photosynthetic tissue. A clear gel-like tissue fills the rest of the leaf. This watery tissue is what stores the majority of the lithops resources. So much resources are stored in this tissue that in fact; if the lithops were to lose its roots completely, it should be able to survive as it regrows them.
Growing lithops is often the first hurdle for a beginning succulent cultivator. Lithops require a more specific set of care requirements to be healthy and happy than most other succulents. Lithops, like cacti, enjoy very porous, well draining, mineral heavy potting mediums. At Succulence, we use a medium that will drain and dry out much quicker because lithops are much more prone to root rot than echeveria and other common ornamental succulents. The best lithops potting mix from my experience is a 50-50 mix of decomposed granite to pumice. This mix not only drains fast, but it also saturates very evenly when it is watered. The best attribute of this mix is that it does not remain wet for very long. This allows the plant to drink deeply from well saturated soil, then quickly the pot can quickly dry out and stave off rot growth.
The ideal lighting conditions for growing lithops is in full sun. Lithops will survive, and in some cases plump up and look overall more succulent, when given light shade. These plants will not survive a snowy or wet winter outdoors. They are relatively cold tolerant however, when their roots are dry.
The greatest challenges of Lithops have to do with its watering cycle and growth cycle. Lithops come from the areas of South Africa that more commonly receive moisture from rains in the summer, and are overall drier over the winter. They have adapted to this by creating a kind of internal calendar for their metabolism, with the times of the year playing very important roles in the plant's growth cycle.
In habitat, around the time when the droughts begin, Lithops’ roots will go dormant. They will subsist completely on the water stored in their two leaves. Over this period these leaves will slowly shrivel as these resources are depleted.
Budding from in between them however, will be the start of two new leaves. This is the beginning of the process called “splitting.” Over the coming months, these leaves will grow slowly as the outer leaves are depleted. By the time the new leaves are well defined, the older leaves have been reduced to a husk that hugs the new growth; until it cracks or is split by the new growth and is washed away by the soon to come rain.
This process causes a lot of confusion for those who are new to succulent cultivation. However, it is a straightforward schedule once you have committed to a seasonal schedule and also use observable changes to make decisions on watering (a seasonal schedule means that at some points of the year, water will be completely or partially withheld). For Lithops, keep them as dry as you can during Fall and Winter to mimic their natural environment’s drought cycle. This way you can be sure that your plant isn’t receiving water when its roots have gone dormant.
When any plant's roots go dormant they become much more highly sensitive to moisture and rot conditions, especially in cultivation. Many plants also display physical signs of their dormant periods as well. To notice that your Lithops have begun “splitting,” look for the beginnings of new leaves budding in the crack between older leaves. This is a sign that the roots have most likely gone dormant, meaning you can begin withholding water. Once the essential skills to cultivate Lithops have been attained, keeping to a watering schedule and being able to observe changes in your plant, you will find these plants to be very rewarding. Most other rare cacti and succulents also follow similar watering and care procedures as well, so lithops present a more economic stepping stone to learning how to care for more expensive and delicate plants.
Watch Out For:
The only other risks to lithops in cultivation other than rot related issues are roundworms, scale, and other kinds of mealy bug. All of these can be easily treated by changing the soil and spraying the entire surface of the leaves of the plant with insecticide.
The greatest threat to lithops in habitat is human development and interaction. The fact that lithops do not spread seed very long distances and also reproduce more viably by splitting concentrates each species and variation into specific localities. This makes their populations especially vulnerable when faced with road and urban development. Due to the amount of specialization Lithops display from locality to locality; entire very specialized populations could be wiped off the map before they are even able to be categorized.
This has spurred both Lithops researchers and conservationists to faster action. These botanists find themselves racing to document every species, its variations, and type localities before they disappear. Working often in correlation with these types of researchers are also conservationists that work to reintroduce species back into the wild. Their work often consists of growing lithops in large greenhouses or “farms” out near the species origin. The colonies are reintroduced and the area is fenced and monitored for both protection from predatory animals and predatory humans; poachers, land developers, or vandals.
These areas will be monitored for at least the next ten years as more specimens are introduced. When the areas have been sufficiently repopulated, the conservation groups plan to de-fence the area.
As more people take notice of lithops, more support and funding could head towards these conservation efforts. We can also rest easy as these days lithops cultivation is very popular across the world, and a high percentage of plants in trade (including our own!) are seed grown. However, as always be wary when purchasing larger or older specimens.