First and foremost, we are different genera within the same family, Aizoaceae. I, a Lithops, belong to the genus *Lithops*. My cousin, often called a Split Rock, belongs to the genus *Pleiospilos*. This fundamental genetic difference is the root of all our physical and physiological distinctions. While we both evolved in the harsh, arid landscapes of Southern Africa and developed similar survival strategies (like mimicry and water storage), our evolutionary paths diverged, leading to unique characteristics.
This is the most noticeable difference. We Lithops typically possess only a single pair of leaves at a time. These leaves are fused together at their base, forming a single, cone-shaped body with a central fissure or "split" from which flowers and new leaf pairs emerge. Our entire survival strategy is based on this single pair; we absorb our old leaves to fuel the growth of the new ones. In contrast, a Split Rock (*Pleiospilos nelii*) often has two, three, or even four pairs of leaves simultaneously. They do not reabsorb their old leaves as quickly or as completely as we do, leading to a multi-layered, stacked appearance that is very uncharacteristic of a true Lithops.
Our floral displays also provide a clear clue. I, a Lithops, almost exclusively produce a single, daisy-like flower from the fissure between my leaves. While on rare occasions two might appear, a solitary bloom is the rule. The Split Rock, however, is a much more prolific bloomer. It is common for a mature *Pleiospilos* to send out two, three, or even four vibrant flowers at once from its central cleft. This generous floral display is a key identifier.
While both of our leaf surfaces are covered in patterns of dots and lines (known as "windows" for channeling light for photosynthesis), the texture is different. My Lithops skin is generally smoother, though it can have slight ridges. The patterns are often intricate, resembling the rocky quartz fields of our native habitat. The Split Rock's leaf surface has a more distinctly rough, bumpy, or pitted texture. Its patterns are typically larger, darker, and more scattered across the surface rather than forming fine, dense networks.
Our overall forms differ upon closer inspection. A Lithops body is generally more uniformly shaped, often described as an inverted cone or a hoof. The fissure between my leaves is usually quite shallow, not cutting deeply into the body. The Split Rock has a much more rounded, chunkier, and rock-like profile. Its famous "split" is typically a very deep, dramatic cleft that divides the plant into two distinct, bulbous halves, making it look like a geode that has been cracked open.
