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On the tide line lies the origins of our supermarket

Our first encounter with the plant unfolds in an unfamiliar and enigmatic phenomenon and took place at high speed across the Afsluitdijk. The geometrically arranged basalt blocks disappear under a white haze of floral clouds.

En route to Terschelling for a week of field research on plants on the island, we were given the appropriate introduction to sea kale by islander and ecologist Piet Zumkehr. While cycling along the Wadden coast, Piet made a stop on the cycle path of the basalt dike. Between the blocks of basalt grew leathery grey-green cabbage leaves with a kind of thin broccoli sprouts in the middle. The latest dyke reinforcement has also allowed sea kale to establish itself on the island since about a decade ago.

The origin of sea kale is around the Mediterranean Sea. For 5,000 years, sea kale has been gathered along the coast as a source of food. The name Crambe comes from the Greek krambe and means cut. And this reveals the unpoetic human relationship to the plant. It has been a widely eaten vegetable for centuries, providing the daily necessities of life. Sea kale is, in a way, the mother of all cabbages. This salt-loving wild cabbage has been found in the Netherlands since 1925 and was first observed in Zeeland. The migration of the sea kale towards the Netherlands was partly made possible by human interventions on the coast in the form of basalt blocks, which, like the landscapes related to the origin of the sea kale, can retain heat for a longer period of time and thus form an ideal environment for this native plant.

Black mustard, rapeseed and wild cabbage belong to the same cruciferous (brassicaceae) family, they are also the three ancestors of many cabbage species. Cabbages such as red cabbage, palm cabbage, Brussels sprouts, cauliflower, kale or broccoli, are all direct descendants of the three wild plants that make up the Triangle of U. In the 1930s, Korean-Japanese botanist, Woo Jang-choon researched the evolution and relationships between members of the plant genus Brassica. His theory, called the Triangle of U, states that the DNA of these three ancestral species of Brassica crossed naturally. From this cross-pollination, new plants emerged and started crossing among themselves. Studies on DNA and proteins have confirmed this theory. Around the world today, we find hundreds of cultivated vegetables that have sprung from this triangular relationship.