Giant Musselburg Organic Leek Seeds Heirloom Vegetable. Leaves are a medium green with a nicely elongated stem 20-22.5 cm (8-9″) in length and between 5-7.5 cm (2-3″) thick. The mild tasting, white stems are absolutely delicious in stews, soups and other dishes. This leek has been an essential component in European cuisine since the 1830’s.