The potato plant, Solanum tuberosum, is a herbaceous perennial cultivated globally as an annual crop, belonging to the nightshade family, Solanaceae. While most people only interact with the underground tuber, the above-ground portion of the plant possesses distinct characteristics useful for identification. The physical features of the potato plant reveal its close relation to other nightshades, such as tomatoes and peppers.
The Stems and Overall Height
The potato plant exhibits a bushy, somewhat sprawling growth habit, rising from the soil on several main stems that originate from the planted seed piece. Depending on the cultivar, the plant typically reaches a height of 2 to 3 feet, though some varieties can grow taller. The main stems are thick, often ribbed or angular in cross-section. Stems are usually hairy and range in color from green to a purplish hue, especially near the base. This structure supports the dense foliage above ground for capturing sunlight.
Distinctive Leaves and Blooms
The foliage of the potato plant is lush and dark green. Potato leaves are compound, meaning they are composed of multiple smaller leaflets arranged along a central stalk in a feather-like pattern. Each leaf typically consists of roughly four pairs of leaflets, which often have slightly serrated edges and a fuzzy texture.
At the end of the vegetative growth phase, the plant often produces star-shaped flowers in clusters called cymes at the tips of the stems. These blossoms typically have five fused petals and a prominent yellow center. Flower color is diverse across varieties, appearing in shades of white, pink, blue, or purple. Following successful pollination, the plant may produce small, round, green fruits that resemble miniature tomatoes. These berries contain the plant’s true seeds but are toxic due to the presence of solanine, as are the leaves and stems. Most commercial varieties focus energy on tuber growth and either rarely flower or drop their flowers before fruit develops.
How the Potato Grows Underground
The potato is a specialized underground structure called a tuber, which is a modified stem, not a root. Tubers develop on the ends of thin, horizontal underground stems known as stolons. Stolons grow out from the base of the main stem, and their tips swell with accumulated starches produced by the leaves above ground. The tuber functions as a nutrient storage organ, allowing the plant to survive dormant periods. On the surface are small depressions called “eyes,” which are dormant buds arranged in a spiral pattern. These buds are capable of sprouting new stems and leaves, which is why a potato can be planted to produce a genetically identical new plant.