The potato plant, Solanum tuberosum, is a globally important crop. While the subterranean tubers are familiar, the above-ground foliage possesses specific characteristics that allow for accurate identification. Understanding the visual details of the potato plant’s leaves is useful for distinguishing it from similar-looking plants in the nightshade family. This guide provides a visual breakdown of the potato plant’s foliage.
The Distinctive Structure of Potato Leaves
A mature potato leaf is a complex structure known as a pinnately compound leaf. It is composed of several smaller segments, called leaflets, attached to a central stalk. Each compound leaf typically features between seven and eleven leaflets organized along the main vein.
The leaflets are generally oval or ovate-lance shaped, often displaying a slightly wavy or serrated edge. Healthy foliage is a rich, medium to dark green with a matte finish. The surface of the leaf may feel slightly rough or hairy, and crushing a leaf releases a distinctly earthy scent.
A unique identification feature is the presence of two distinct sizes of leaflets. Larger primary leaflets are arranged in pairs, with a terminal leaflet at the tip of the central stalk. Smaller, intermediate leaflets are nestled between these larger pairs, giving the overall leaf a slightly crowded appearance. This layered arrangement is a hallmark of the potato plant’s foliage.
Growth Habit and Appearance on the Stem
The potato plant grows as a bushy, sprawling herbaceous plant, often reaching one to three feet at maturity. The foliage is dense, forming a thick canopy that maximizes the plant’s ability to capture sunlight. This canopy is supported by sturdy stems that can be green, but often take on a purplish or reddish tinge where exposed to light.
The leaves emerge from the main stem in an alternate pattern, meaning each leaf grows individually at a different height. This alternate arrangement ensures that the upper leaves do not completely shade the lower leaves, contributing to efficient energy production. The thick, angled or winged nature of the stems helps support the substantial mass of the foliage.
As the plant progresses through its life cycle, the appearance of the leaves changes. During the final stage of tuber maturation, the lower leaves naturally begin to yellow and die back. This process of senescence signals that the plant is redirecting its stored energy into the developing underground tubers.
Important Safety Note: Toxicity of Potato Foliage
While the underground potato tubers are edible, all above-ground parts of the plant are considered toxic. The leaves, stems, and any small green fruits that may form after flowering contain high concentrations of a bitter compound called solanine. This substance is a glycoalkaloid, which acts as a natural defense mechanism.
The potato plant produces solanine to protect itself against predation by insects, disease pathogens, and foraging herbivores. Consumption of the foliage, stems, or green, tomato-like fruits can cause adverse reactions in both humans and animals.