An orchid spike is the specialized structure that produces and supports the flowers on an orchid plant, particularly in the common household Phalaenopsis, or moth orchid. This growth is botanically known as an inflorescence, which includes the central stalk, buds, and blooms. Understanding the spike’s development is important for successful orchid care, especially when trying to encourage the plant to rebloom. The spike signals that the orchid is preparing for its reproductive phase, which typically occurs once or twice a year, depending on the variety and growing conditions.
The Anatomy and Role of the Orchid Spike
The orchid spike is a modified stem that emerges from the base of the plant, often growing from a leaf axil (the angle between a leaf and the main stem). In monopodial orchids like Phalaenopsis, the spike grows upward from the single vertical stem, arising from the base of the lower leaves. When it first appears, the spike is a small, rounded nub that quickly elongates and develops distinct segments called nodes.
These nodes are joints on the spike where meristem cells are present. Each node is protected by a small, triangular flap of tissue called a bract. These sites are capable of developing into a secondary flower branch or a keiki (a baby plant). The primary function of the spike is to elevate the flower buds, ensuring they are well-displayed for potential pollinators and allowing the plant to successfully complete its reproductive cycle.
Phalaenopsis orchids commonly produce a lateral spike, meaning it grows from the side and can rebloom from the nodes after initial flowering. A terminal spike grows from the top center of the plant, which is a less common occurrence in household orchids. A plant producing a terminal spike will not grow new leaves from the crown and may instead produce a keiki to continue its growth. The spike requires staking as it grows, as the developing flowers and buds can become heavy, causing the entire structure to bend or snap without support.
Identifying Spikes Versus Roots or Keikis
A common confusion for orchid owners is distinguishing between a newly emerging flower spike, an aerial root, or a keiki when the growth is just beginning. The flower spike typically has a distinct, pointed or slightly flattened tip that often resembles a small mitten. It usually grows upward or sideways, bending toward the brightest light source once it gains length.
A new aerial root is characterized by a blunt, rounded, or cone-shaped tip. Orchid roots are covered in a spongy layer called velamen, which gives them a silvery-green or white appearance when dry, with a bright green tip when actively growing. Unlike spikes, roots tend to grow downwards, or in any direction, searching for moisture and a surface to anchor to. They will not have the small, protective bracts seen on the nodes of a spike.
A keiki, which is Hawaiian for “baby,” is the least common of the three and looks like a miniature version of the mother plant. It has small, developing leaves and often appears on one of the nodes along an existing, mature flower spike, though they can also emerge from the base of the plant. If the new growth has tiny leaves, it is a keiki, which is a clone of the original orchid.
Caring for the Spike After Flowering
Once all the flowers have dropped from the spike, the plant enters a resting phase, and the owner has three main options for managing the spent structure. If the entire flower spike turns yellow or brown, it is dead and should be cut off completely. This cut should be made as close to the base of the plant as possible without damaging the leaves, allowing the orchid to redirect energy into producing new leaves and roots.
If the spike remains green and healthy, it has the potential to produce a secondary bloom or a keiki from one of its dormant nodes. For a secondary bloom, the common practice is to cut the green spike about one inch above the second or third node from the base. This encourages the meristem cells at that node to activate and produce a side branch. However, the resulting flowers from this second bloom are often smaller and fewer in number, and this process can stress a weaker plant.
The third option is to simply leave a green spike alone, especially if the plant is a novelty hybrid or a specific species known to rebloom repeatedly from the tip. In all cases of cutting, use a sharp, sterilized tool, such as scissors or pruning shears, to prevent the introduction of pathogens to the fresh cut. Sterilizing the tool with rubbing alcohol or a flame before each use helps maintain the plant’s health.