The Calla Lily, a popular flower known for its elegant, trumpet-shaped blooms, is botanically classified under the genus Zantedeschia. While often sold and referred to as a “bulb,” this common name is scientifically inaccurate. The Calla Lily grows not from a true bulb, which is a layered structure like an onion or tulip, but from a specialized underground storage organ called a rhizome. This modified stem grows horizontally, and understanding its distinct anatomy is the first step in successful cultivation.
The Core Anatomy of the Calla Lily Rhizome
The dormant Calla Lily rhizome is a dense, fleshy structure that serves as the plant’s food and energy reserve during its rest period. Unlike the symmetrical, layered form of a true bulb, the rhizome typically presents an irregular, lumpy, or oblong shape, often described as kidney-like or similar to ginger root. Commercially available specimens are generally between one and three inches in diameter. Larger rhizomes tend to produce more vigorous plants and a greater display of flowers.
The exterior color of a healthy, dormant rhizome is usually a muted tan, off-white, or light brownish hue. Its surface texture is firm to the touch, feeling slightly rough or somewhat wrinkled, which is a normal sign of dehydration during dormancy. This surface may also appear segmented or show rings from previous growth. The dense, starchy interior stores the carbohydrates needed to fuel the next season of growth.
Determining Up From Down for Planting
Correctly orienting the Calla Lily rhizome can be challenging due to its irregular shape. The most reliable feature for identifying the top side is the presence of small, visible “eyes,” which are the growth buds or nodes from which new shoots will emerge. These growth points may appear as small bumps or sprouts, sometimes showing a slight pink or green tinge if the rhizome is beginning to break dormancy. The eyes are typically concentrated on a flatter or slightly concave surface.
The bottom of the rhizome, where the roots will develop, presents a contrasting appearance. This side is often rougher or more convex and may show residual root scars or thin, dried remnants of the previous season’s root system. When planting, place the rhizome with the side containing the eyes facing upward toward the soil surface. Planting it upside down can delay growth or cause shoots to grow in a distorted manner.
How to Identify a Healthy Rhizome
A high-quality rhizome will feel heavy for its size and be firm when gently squeezed. The skin should look dry and intact, though a slight amount of surface wrinkling is normal, indicating it is in a healthy, dormant state. This firm texture is the most reliable indicator of substantial stored energy.
Conversely, signs of a distressed rhizome include softness, mushiness, or a light, hollow feeling, which often indicate internal rot due to excessive moisture during storage. Visible signs of mold, such as patches of blue or green fuzz, also point to fungal infection. While minor cuts and scrapes are usually harmless, a deeply shriveled appearance suggests significant dehydration or poor storage conditions.