The genus Lithops is a group of dwarf succulent plants native to the arid regions of southern Africa, commonly known as Living Stones due to their remarkable camouflage among pebbles. They have developed unique methods of proliferation specific to their harsh, drought-prone environment. Lithops multiply in two distinct ways: an increase in the number of leaf pairs on a single plant (asexual splitting), and the creation of new, genetically unique individuals through seeding (sexual reproduction). Both forms of multiplication are slow processes tied to the plant’s unusual annual growth cycle.
The Mechanism of Asexual Increase: Splitting
The multiplication most often observed by growers is the asexual process of “splitting,” which increases the number of “heads” or leaf pairs on a single plant. Each Lithops head consists of two bulbous, fused leaves separated by a fissure. Division begins when a new leaf pair starts to grow from the meristem located deep within the central fissure.
This new pair of leaves actively consumes the moisture and nutrients stored within the old, outer leaves. As the new leaves grow, they physically push apart the old ones, causing the characteristic “split.” The old leaves shrivel and dry out, eventually forming a papery sheath around the newly emerged leaves, ensuring the plant recycles its resources efficiently.
The process of splitting is not guaranteed to increase the head count every year; typically, one old head is replaced by one new head. However, when conditions are right, the meristem may divide, resulting in the old single head being replaced by two, or occasionally more, new heads. This division creates a cluster of genetically identical plants, allowing a single Lithops to gradually form a large clump over many years.
Sexual Reproduction: Flowers and Seeding
True population multiplication, resulting in genetically diverse new plants, occurs through sexual reproduction involving flowers and seeds. Mature Lithops typically flower in the late summer or autumn, producing a single, daisy-like flower—either white or yellow—that emerges from the central fissure. These flowers are often large relative to the plant body and can last for about two weeks.
For seed production to occur, the flower must be pollinated, a process that usually requires pollen from a genetically distinct plant. Most Lithops are not self-fertile, necessitating cross-pollination to form a viable seed capsule. After successful pollination, a small, woody seed capsule develops and takes approximately nine months to mature.
The seed capsule has a unique mechanism for dispersal called hygroscopic action, meaning it opens only when it comes into contact with water, such as rain. This adaptation ensures the tiny seeds are released during conditions favorable for germination. Collecting and sowing these seeds is the primary method for growers to propagate a large number of new, individual Lithops plants.
Managing the Annual Growth Cycle for Successful Division
The success of Lithops division is directly dependent on managing the plant’s annual growth cycle, which is essentially the reverse of many common houseplants. Lithops are summer-dormant, resting during the hottest months, and actively grow during the cooler periods of autumn, winter, and spring. This unusual cycle dictates a strict watering schedule that must be followed to encourage healthy splitting and prevent rot.
Dormancy and Withholding Water
The most sensitive period for the plant is during the late fall and through the winter, when the new leaves are developing inside the old ones. During this time, water must be completely withheld, starting around the late fall and continuing until the old leaves have dried into a papery husk, which typically happens in the spring. The new leaves must be forced to draw all their required moisture and nutrients from the old leaves. Watering during this phase will cause the new leaves to prematurely plump up, leading to “leaf stacking” or rot.
Active Growth and Watering
Once the old leaves have completely dried, usually in the spring, the new head is revealed and the plant is ready to begin its growth period. This is the time to resume deep watering, which helps the new leaf pair mature and prepares the plant for the next stage of its cycle. Watering should continue through the spring and early summer before being stopped again as the plant enters its summer dormancy. Following this specific cycle, rather than simply watering on a fixed schedule, successfully facilitates the doubling of heads.