Calatheas are popular houseplants, admired for their striking foliage. A common question concerns their underground structures, specifically whether they possess corms, which are often confused with other subterranean plant parts.
Corms and Rhizomes Explained
Plants develop specialized underground structures for nutrient storage and reproduction. Two common types are corms and rhizomes, each with distinct characteristics.
Corms are swollen, vertical underground stems that primarily store food. They appear solid when cut and produce roots from their base and leaves from their top. Gladiolus and crocus are common examples.
Rhizomes, in contrast, are horizontal underground stems that produce roots and shoots from their nodes. They grow laterally, spreading outwards. Unlike corms, rhizomes have nodes and internodes and store starches and proteins. Ginger and irises utilize rhizomes for growth and propagation. The key distinction is that corms are vertical, solid storage organs, while rhizomes are horizontal stems with nodes, facilitating spread and new growth.
Calathea’s Subterranean Structure
Calatheas are rhizomatous plants, meaning they do not have corms. Their underground structures are rhizomes, modified stems that grow horizontally. These rhizomes are often described as chunky, “noduled” or “pear-shaped” cream or brown structures. When repotting, they can resemble bulbs or thick roots.
Rhizomes serve as vital storage organs for the Calathea, holding starches, proteins, and other nutrients. This energy reserve is crucial for the plant’s survival and new growth. New shoots and roots emerge from the nodes along these stems, allowing the Calathea to spread and form new plantlets, resulting in a clumping growth habit in potted environments.
Caring for Calathea Rhizomes
Knowing Calatheas are rhizomatous is helpful for their care, particularly watering and potting. Since their rhizomes store water and nutrients, overwatering is a significant concern, leading to root rot. Allow the top inch or two of soil to dry out between waterings, ensuring the soil remains consistently moist. Use well-draining soil, often a peat-based mix with added perlite or orchid bark, to prevent waterlogging.
Choose a pot with adequate drainage holes. While Calatheas appreciate being somewhat snug, the pot should offer enough space for rhizome spread and new growth. Propagation is primarily achieved through rhizome division. This involves carefully unpotting the plant, gently separating rhizome clumps, ensuring each division has roots and at least one or two shoots, and then replanting them. Healthy rhizomes are firm and light-colored; mushy or discolored ones indicate root rot, often from excessive moisture.