The primary method of identifying Haworthiopsis species is through a close examination of their leaves. Unlike many succulents, their leaves are typically firm, often triangular or deltoid, and arranged in a tight, spiral rosette. Key characteristics to observe include the leaf's surface texture. Some species, like Haworthiopsis attenuata, are covered in raised, white, pearly tubercles (warts) that can be densely packed. Others, such as Haworthiopsis limifolia, feature distinct, raised, transverse ridges, giving the leaves a coarse, file-like texture. The presence, density, and pattern of these markings are critical diagnostic tools. Furthermore, note the leaf's color, which can range from deep green to brownish or even reddish when stressed by sun, and its shape, whether it is long and slender, short and stubby, or markedly recurved.
The overall architecture of the plant provides significant clues. Haworthiopsis species are generally small, slow-growing, and stemless or with a very short stem. Their growth habit can be solitary or clustering (producing offsets to form a dense clump). For instance, Haworthiopsis coarctata is known for its columnar, tightly packed rosettes that stack vertically on a short stem, often producing many offsets. In contrast, Haworthiopsis reinwardtii also grows tall but its leaves are less tightly packed, revealing more of the stem. The size of the rosette is another factor; some species like Haworthiopsis fasciata (often mislabeled) form rosettes up to 15 cm in diameter, while others remain much more compact.
While the foliage is the main attraction, the flowering structure can offer definitive identification. Haworthiopsis plants produce slender, simple inflorescences (flowering stalks) that emerge from between the leaves. The flowers themselves are small, tubular, and two-lipped, typically white or pale pink with green or brown veins. A key differentiator from the closely related Haworthia genus is the shape of the flower's base. In Haworthiopsis, the flower tube is typically straight and narrows evenly towards the base. Observing the timing of the bloom can also be helpful, though many species flower in the summer months.
It is crucial to distinguish Haworthiopsis from its relative, the genus Haworthia. Generally, Haworthiopsis have tougher, darker, and more opaque leaves, often with prominent tubercles or ridges. They are also generally more tolerant of direct sunlight. A common point of confusion is between Haworthiopsis attenuata and Haworthiopsis fasciata. The latter is much rarer in cultivation and is identified by its smoother, inwardly curved upper leaf surface, with tubercles predominantly on the outer underside. Haworthiopsis attenuata has tubercles on both sides of the leaf. Accurate identification often requires comparing multiple characteristics rather than relying on a single trait.
