The horseradish plant (Armoracia rusticana) is a hardy perennial belonging to the Brassicaceae family, which includes vegetables like broccoli and cabbage. While the plant produces foliage and flowers above ground, it is primarily cultivated globally for its substantial, pungent root. This root is traditionally grated and prepared as a popular, fiery condiment.
The Distinctive Leaves
The foliage is the most prominent visual feature above the soil, forming a dense, bright green rosette. The largest leaves, called basal leaves, emerge directly from the crown on long stalks, sometimes reaching up to one meter (over three feet) in length.
The leaves are coarse and textured, with a dark green color that can appear slightly glossy. Their edges are wavy, crenated, or bluntly toothed, giving them a rugged, undulating look. Leaves higher on the flower stalk are generally smaller and may have a more lobed or dissected shape.
Root Structure and Growth Habit
Below the surface, the horseradish plant develops a thick, fleshy taproot, which is the prized culinary component. This root is typically white on the inside, with a brownish or off-white color on the exterior skin. When mature, the main root is cylindrical and tapered, growing deep into the soil.
The plant is a robust grower, usually reaching 60 to 90 centimeters (about two to three feet) in height when not flowering. Its perennial nature means the plant persists year after year, spreading aggressively through root offsets and lateral roots. Even small root fragments left in the soil can quickly sprout a new plant, making horseradish potentially invasive in garden settings.
Flowers and Seed Production
Established horseradish plants typically produce a tall, upright flowering stalk, known as bolting, usually appearing in late spring or early summer. This stalk elevates the flowers above the main rosette, sometimes pushing the plant’s height up to 1.5 meters (five feet). The flowers are small, pure white, and possess four petals arranged in the cross shape characteristic of the Brassicaceae family.
These blossoms are clustered in terminal panicles or racemes at the top of the stalk. Following the bloom, the plant may form small, oblong seed pods known as siliques. However, horseradish has low fertility, and the seeds it produces are often sterile or lack viability. For this reason, the plant relies predominantly on vegetative propagation via its root system to spread.