Orchid nodes are small, often subtle parts of an orchid plant that hold significant potential for new growth. These unassuming areas serve as starting points for various plant structures, from new leaves and roots to flower spikes and even entirely new orchid plants. Understanding the function and location of these nodes is an important aspect of successful orchid cultivation and propagation.
Understanding Orchid Nodes
From an anatomical perspective, an orchid node is a compact area of meristematic tissue, which consists of undifferentiated cells capable of developing into specialized plant structures. These nodes appear as small bumps or slight swellings along a plant’s stem, covered by a protective, papery layer called a bract. Orchid nodes are commonly found on the flower spikes of Phalaenopsis orchids, along the main stem of monopodial orchids like Vandas, and sometimes on the pseudobulbs of sympodial orchids such as Cattleyas and Dendrobiums.
Types of Growth from Orchid Nodes
Orchid nodes can give rise to a variety of growths, each serving a different purpose for the plant. One common outcome is the development of secondary flower spikes. This occurs on existing flower stalks, where dormant nodes can activate to produce additional blooms, extending the flowering period. Another type of growth from nodes is a “keiki,” which is Hawaiian for “baby.” Keikis are genetically identical clones of the mother plant, appearing as miniature plantlets with their own leaves and eventually developing roots. While they can form naturally, sometimes triggered by environmental factors or stress, they represent a method of asexual reproduction for the orchid. Nodes might also produce aerial roots, particularly on monopodial orchids, or a new branch.
Propagating Orchids Using Nodes
Propagating orchids through nodes, especially by encouraging keikis, is a common method for expanding an orchid collection. To do this:
Identify dormant nodes on a spent flower spike, covered by a small, papery bract. Carefully remove this bract to expose the node.
Apply keiki paste, a hormone-based substance containing cytokinin, to the exposed node. This stimulates cell division and growth, encouraging keiki development over a flower spike.
Provide suitable environmental conditions, such as consistent humidity and indirect light, to support the new plantlet’s development.
Allow the keiki to mature on the mother plant until it develops at least two to three leaves and roots one to three inches long.
Once mature, carefully separate the keiki by cutting the flower spike one to two inches above and below it, ensuring a small piece remains attached.
Treat cut surfaces on both the keiki and mother plant with a fungicide like cinnamon to prevent infection.
Caring for Orchid Nodes
Maintaining the health of orchid nodes involves general good plant care practices and specific attention to the nodes themselves. It is advisable to avoid unnecessary handling of nodes, as they are potential sites for future growth. Ensuring the orchid receives appropriate environmental conditions, including adequate humidity and light, supports the plant’s overall vigor and the nodes’ ability to develop. When an orchid’s flowers have faded, decisions about cutting the spent flower spike often involve the nodes. If the spike is still green and has unused nodes, cutting it just above a viable node (often the second or third node from the base) can encourage a new flower spike or a keiki. However, if the entire flower spike turns brown or yellows, it indicates the plant has withdrawn energy from it, and it can be cut closer to the base. This allows the plant to conserve energy and direct it towards new growth from its core.