Brassica oleracea var. sabellica
Kale is a sturdy, slightly bitter brassica green. It tolerates cool Northeast conditions and remains structurally leafy rather than forming the dense head seen in cabbage.1
Kale contains glucosinolates, sulfur-rich plant compounds characteristic of the brassica family.2
Kale is one of the non-heading forms of Brassica oleracea: a species also selected into cabbage, broccoli, cauliflower, and brussels sprouts. The wild ancestor is a seaside-cliff plant of the Mediterranean and southwestern Europe, and the leafy, non-heading forms that became kale were selected for edible leaves rather than heads.34
The Northeast’s cold season is where kale earns its reputation. UMass Extension’s Cold-Hardy Greens Project has spent several winters at its South Deerfield research farm selecting brassica greens suited to cold-climate New England, and Vermont growers report picking kale from open fields and tunnels through the winter.56
Footnotes
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University of Maine Cooperative Extension, “Vegetables and Fruits for Health: Greens,” accessed July 17, 2026. ↩
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U.S. Department of Agriculture Agricultural Research Service, “Glucosinolates,” accessed July 17, 2026. ↩
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University of Maine Cooperative Extension, “Get Creative with Cabbage,” 2024. ↩
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John Vaughan and Catherine Geissler, The New Oxford Book of Food Plants, 2nd ed. (Oxford University Press, 2009), p. 178 (PDF p. 213). ↩
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UMass Extension, “Cold-Hardy Greens Project”, Vegetable Notes, May 2009, accessed August 5, 2026. ↩
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UVM Extension, “Vermont Vegetable and Berry News”, December 2011, accessed August 5, 2026. ↩