Sea kale (Crambe maritima) is a remarkably hardy perennial plant native to the coasts of Europe, historically valued as a versatile vegetable. Once known as “scurvy grass,” it was often pickled and taken on long sea voyages by sailors due to its high content of Vitamin C. It was a well-regarded food source that saw a decline in popularity but is currently experiencing a culinary revival. The plant’s deep roots and tolerance for salt have allowed it to survive and flourish where few other vegetables can.
Identifying Characteristics and Habitat
It belongs to the Brassicaceae family, which also includes common cabbage and broccoli. It is a robust, mound-forming perennial that establishes a deep, extensive root system, allowing it to withstand the harsh coastal environment. The plant is easily recognized by its large, fleshy leaves, which possess a distinctive waxy, blue-green color and a wavy, crinkled edge.
Growing up to 75 centimeters tall, the plant produces abundant clusters of small, four-petaled white flowers in summer, which are highly aromatic and often described as honey-scented. The flowers are followed by small, globular seed pods containing a single seed, which are buoyant and dispersed by the sea. As a halophyte, sea kale specifically thrives on shingle beaches, sandy shores, and coastal cliffs, generally establishing itself above the high tide line where it tolerates significant salt spray and nutrient-poor soil.
Culinary History and Edible Parts
The use of sea kale as a food source dates back centuries, with historical records suggesting its consumption by coastal populations. It gained significant popularity in Britain starting in the early 18th century when it began to be cultivated in private gardens. By the Victorian era, blanched sea kale shoots became a fashionable delicacy.
Nearly every part of the plant is edible, though the young shoots are the most highly prized. These shoots are traditionally harvested in early spring and blanched—a process of covering the emerging growth with soil or a pot to exclude light—which yields pale, tender stems with a delicate, nutty, and slightly sweet flavor. The unblanched, young leaves can be cooked like common kale or spinach. The unopened flower buds are sometimes prepared as a substitute for broccoli florets, and the small, pea-like seed pods are edible when young.
Nutritional Profile
Sea kale contains beneficial compounds known as glucosinolates, which contribute to its characteristic flavor. The fresh green leaves of Crambe maritima are high in moisture, with a low energy content. A 100-gram serving of the fresh leaf contains around 3.50 grams of protein, a minimal 0.30 grams of fat, and only 1.30 grams of total carbohydrates.
It is particularly valued for its micronutrient density, possessing a high concentration of Vitamin C, which was historically leveraged to prevent scurvy. Sea kale is also a good source of several important minerals, including calcium, magnesium, manganese, and potassium. The plant’s leaves accumulate high levels of Vitamin A precursors and may contain iodine when grown in native coastal soils rich in marine organic matter.