Lithops (LITH-ops) - "Living Stones"
Aizoaceae
Relatives: Faucaria, Delosperma
Lithops is a genus of succulent plant in the Ice Plant Family. Members of this genus are native to Southern Africa and their name is derived from the Ancient Greek words meaning “stone” and “face”, a reference to the stone-like appearance of the plants. They avoid being eaten by blending in with the surrounding rocks and are often referred to as “Pebble Plants” or “Living Stones”. Although the name Lithops appears to be plural, it actually also refers to a single plant.
Individual Lithops plants consist of one or more pairs of bulbous, almost fused leaves opposite to each other with hardly any stem visible. The slit between the leaves contains the meristem (a type of tissue found in plants) and is where the flowers and new leaves are produced. The leaves of Lithops are mostly buried below the surface of the soil, with a partially or completely translucent top surface known as a fenestration or ‘leaf window’ which allows light to enter the interior of the leaves.
During winter a new leaf pair, or occasionally more than one, grows inside the existing fused leaf pair. In spring the old leaf pair parts to reveal the new leaves and the old leaves will then dry up. In its natural habitat you almost never have more than one leaf pair per head, presumably as an adaptation to the arid environment where they are found. Yellow or white flowers emerge from the fissure between the leaves after the new leaf pair has fully matured, with one per leaf pair.
Lithops are more sensitive to overwatering than most other succulents and in fact should NOT be watered at all during fall and winter. The succulent leaves contain all the water they need to survive and support their new growth in the spring. Even in summer when the plant is actively growing, it should still only be watered when the tops of the leaves show extreme wrinkling.