Crown daisy
The tender leaves and stems of the garland chrysanthemum, a leafy green with a strong herbal, slightly bitter aroma.
Garland chrysanthemum, called ssukgat in Korean, is a chrysanthemum species grown specifically as a vegetable for its young leaves and stems. It tastes distinctly herbal and resinous, somewhat like celery and meadow herbs, with a gentle bitterness. The leaves wilt quickly when heated and turn bitter and mushy if overcooked, so they usually go into soups, stews and hot pots at the very end or are only briefly blanched for side dishes. You can find it at Asian grocers, often also under its Japanese name shungiku, especially in autumn and winter. Seeds are sold at garden centres and by mail order, and the plant grows quickly and does well in a pot on a balcony.
Substitute:
There is no real substitute, because the peculiar chrysanthemum aroma is not found elsewhere. The closest approach is watercress or rocket mixed with a little celery leaf, which hints at the bitterness and herbal note; young spinach matches only the texture and makes the dish noticeably milder.