Crambe maritima. Not the common sort of kale, although somewhat similar in appearance. Sea kale is an attractive, blue-green, leathery leaved plant that grows wild on European sea shores. It is a pretty forgiving perennial vegetable. Once you have one plant, you can easily propagate it by breaking up the roots during the dormant season. You can eat all parts: shoots, roots, florets, leaves, and even green seed pods.
These seeds are the product of open pollination between plants from many sources. You should see variations in leaf and stem color, plant size, and earliness of flowering, among other things. Select the plants you like best and propagate them by taking root cuttings.
Intact seeds still have the corky periderm. While sea kale seeds will germinate just fine without this removed, they will germinate a bit faster and more evenly when it is removed. Intact seeds store better than shelled seed, so if you plan to store seed for future years, you should buy intact seed. Typically, with intact seed, 10 to 15% of the shells are empty – they contain no seed.
Shelled seeds have had the corky periderm removed. These seeds will germinate a bit more evenly and the process of removing the shells eliminates empty shells, which are common with sea kale.