True mustard seeds are usually members of the species Brassica juncea, but there are a number of Asian vegetables of the species B. rapa that really belong in this category as well. They are included below. All these greens have a similar range of flavours and spiciness to their leaves - and can be enjoyed raw in salads, as baby greens or full size, or cooked in stir-fries, steamed, braised, or added to soups. These varieties are all relatively similar in growth form, but the leaves themselves are available as highly serrated (mizuna), huge and flat (giant red), concave (tah tsai), and even curled (giant southern curled). All of the varieties listed here are well suited to cool season and even winter gardening. Komatsuna, tah tsai, and mizuna/mibuna are particularly hardy types.
