Yes, cabbage and Brussels sprouts are very closely related, sharing an identical biological heritage despite their distinct appearance. They are, in fact, the same single species of plant. This relationship is a remarkable example of how human intervention can generate dramatic physical differences within a shared genetic blueprint. To understand this connection, one must look past the vegetable aisle and into botanical classification.
The Common Ancestry
Cabbage and Brussels sprouts both belong to the species Brassica oleracea, a plant known in its original form as wild cabbage or sea kale. In the world of plant taxonomy, belonging to the same species means they share the same fundamental genetic makeup and can interbreed.
The dramatic visual difference between the two vegetables is explained by their classification as different varieties or cultivars of this single species. Cabbage is scientifically designated as Brassica oleracea var. capitata, while Brussels sprouts are Brassica oleracea var. gemmifera. This difference signifies that while their DNA is largely the same, humans have intentionally selected for and amplified distinct physical traits. The wild ancestor of Brassica oleracea is a humble, leafy plant native to the coastal regions of Europe, which bears little resemblance to either of its modern descendants.
Specialized Cultivation: How They Became Different
The mechanism that created two such different-looking vegetables from one original species is known as artificial selection or selective breeding. Over centuries, farmers and plant breeders chose specimens of the wild Brassica oleracea that displayed desirable traits and bred them together. This process focused on different parts of the plant for consumption, leading to the physical divergence.
For the development of cabbage, breeders continually selected plants with the largest and tightest terminal bud, which is the main growing point. Through consistent selection, this terminal bud became the dense, large, and solid head recognized as cabbage today. The edible part is essentially a greatly enlarged, undeveloped leaf bud.
In contrast, the development of Brussels sprouts focused on the lateral buds, which are the small growth points found where the leaf joins the main stem. Breeders in Belgium, with records dating back to the 13th century, selected plants that produced numerous, tightly packed, miniature heads along the length of the stalk. The scientific varietal name gemmifera literally means “bud-bearing,” referencing these small, edible lateral buds.
Other Close Relatives in the Cabbage Family
The relationship between cabbage and Brussels sprouts is only one example of the incredible diversity found within the Brassica oleracea species. This single species is the source of many other common vegetables that look nothing alike, all developed by selecting for different parts of the ancestral wild cabbage plant.
This species includes:
- Broccoli, bred by selecting for the undeveloped flower heads and stems (var. italica).
- Cauliflower, developed from the flower structure, resulting in a dense, white curd (var. botrytis).
- Kale, the earliest form to emerge, bred simply for its leafy foliage (var. acephala).
- Kohlrabi, developed by selecting for a swollen, edible stem (var. gongylodes).
This demonstrates that the genetic potential for all these different vegetables was present in the original wild cabbage plant.