Plant runners are specialized, horizontal stems used by many species to reproduce and expand their territory without the need for seeds or pollination. This method of reproduction, known as vegetative or asexual propagation, creates new individuals that are genetically identical to the parent. The runner allows the plant to efficiently colonize nearby ground by extending outward across the soil surface. These structures enable rapid expansion and ensure the survival of the plant’s genetic makeup in a new location.
Defining Plant Runners (Stolons)
The biological term for a plant runner is a stolon, a modified stem that grows along the surface of the ground or just beneath it. Stolons are designed for outward growth rather than for support or nutrient storage. They originate from an axillary bud near the base of the parent plant, extending horizontally.
As a true stem, the stolon possesses nodes and internodes, though the leaves at these points are often reduced to small, scale-like structures. This morphology distinguishes the stolon from a typical vertical stem, prioritizing lateral spread over height. Plants that utilize this reproductive structure include the garden strawberry, the spider plant, and many types of turfgrasses.
The Mechanism of Asexual Propagation
A plant runner functions as a lifeline, transporting resources and genetic material from the parent plant to a distant point. The stolon’s primary function is to facilitate the establishment of a new, independent plant through asexual reproduction. This process begins when a node along the horizontal stem makes firm contact with the soil.
Upon contact, the node is hormonally stimulated to develop adventitious roots. Simultaneously, a new shoot, called a plantlet or ramet, begins to grow upward from the same node. The parent plant continues to supply the developing ramet with water and nutrients through the runner until the new root system is sufficiently established to support itself.
Distinguishing Runners from Similar Plant Structures
The term “runner” is often compared to other structures plants use for vegetative spread, particularly the rhizome. Runners, or stolons, are defined by their position, growing at or above the soil surface, and their slender form. They are dispersal organs, designed to move the plant to a new location.
In contrast, a rhizome is a thickened, subterranean stem that grows horizontally underground. Rhizomes are often fleshy, with shorter internodes, and serve a dual purpose: they are storage organs for carbohydrates and also act as reproductive structures. Because rhizomes remain below the soil, they are more protected and generally thicker than the exposed, more delicate stolons.
Other similar structures include suckers, which are shoots that emerge directly from the root system, and offsets, which are small, complete daughter plants that arise from the base of the parent. Unlike these other reproductive parts, the runner is a visibly trailing, above-ground stem that can produce multiple plantlets along its length before the connection to the parent is eventually severed.
Practical Management and Propagation
The plant runner’s cloning ability makes it a valuable tool for gardeners seeking to propagate certain species. To use a runner for propagation, the plantlet at the node is encouraged to root in a small container of soil while still attached to the parent. Once the plantlet has developed its own robust root system, the slender runner connecting it to the parent is simply clipped.
Management is necessary when the rapid spread of stoloniferous plants, such as lawn grasses or groundcovers, is undesirable. In these situations, regular mowing or the installation of physical barriers can help control lateral expansion. For plants like strawberries, removing excess runners directs the plant’s energy toward developing larger fruit rather than creating new clones.