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Sea Kale

Crambe maritima

  • Written also: Sea-kale
  • Family: Mustard Family – Brassicaceae (Cruciferae)
  • Growing form: Perennial herb.
  • Height: 30–60 cm (12–25 in.). Stem abundantly branched, rigid, glabrous.
  • Flower: Corolla regular (actinomorphic), white, approx. 1.0–1.5 cm (0.4–0.6 in.) wide; petals four, 6–9 mm (0.24–0.36 in.) long. Sepals 4, falling early. Stamens 6, of which 4 long and 2 short. Gynoecium fused, a single carpel. Inflorescence an abundantly flowered, corymbose raceme, extending in fruiting stage.
  • Leaves: Alternate, stalked. Lower leaf-blades lobed–with toothed margins (sometimes entire margins), crinkled, fleshy, glabrous, waxy, bluish green, upper leaf-blades narrow.
  • Fruit: 1-seeded, indehiscent, approx. 10 mm (0.4 in.) long 2-parted silicula with small, stalk-like basal part, tip globose, grooved, net-veined, almost tipless. Stalk approx. 10 mm (0.4 in.), ascending.
  • Habitat: Gravelly and sandy sea-shores.
  • Flowering time: June–July.

Fields of juicy sea kale’s juicy rosettes can cover large areas and with their white flowers they are an impressive sight on open sea-shore shingle. It is classed as a coastal pioneer plant in Finland and is among the first plants to colonise plantless sandbanks. The coast might seem like barren territory, but buried seaweed, plant shoots and sea shells create a fertile environment. Salty seawater is a difficult problem for many plants but sea kale only grows in areas where the water has at least six promilles of salt. In Finland it is thus limited to the Åland Islands and the south-western archipelago, while on the mainland it only grows around the sandy beaches of the Hanko peninsula. The Denmark Sound occasionally pushes the saltier water of the Atlantic into the Baltic Sea, which raises the salinity of the brackish water. After this influx of salt water sea kale spreads and can be found growing as far away as the northern archipelago. The plant’s fruits are able to float for months and remain viable in the slightly salty water of the Baltic, so it spreads far on the currents. Sea kale has spread to Finland’s shores – and probably will again sometimes – from Estonia.

Sea kale has been a popular vegetable along the Atlantic coast for centuries. Plots were covered in sand so that young shoots would not go green as the blanched stalks are delicious and are eaten like asparagus. The wild plants are edible and are best eaten young because they become bitter as they grow. Sheep are very fond of the plant too and have wiped it out on large areas of the Finnish archipelago. It is also a popular perennial abroad because of its bluish green colour. The inflorescence is large and impressive, and the white flowers smell of nectar and attract an abundance of pollinators.

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