Look for deeply cut leaves with silver undersides. Mugwort, aka False Chrysanthemum, spreads by long rhizomes just under the soil. Removing the whole network is key, early, or it bounces back quickly. I spent a good 3 hours pulling mugwort out from my front border when my neighbor, dear Anda, stopped by and asked me if she could take it home. Confused, and hardly one to refuse, I handed the whole lot over as she explained to me how mugwort is enjoyed a hearty green for soups back in her home country, Romania.
As I learned, where it is welcome, it is a kitchen herb. The bitter, faintly sage-like leaves were the classic European seasoning for fatty roasts — goose, pork, duck, fish — stuffed in to cut the richness and settle digestion, and they bittered medieval gruit ales before hops took over. In East Asia it is still eaten daily: as Japanese yomogi, blanched and pounded into grassy-green kusa-mochi and dango, and as Korean ssuk in early-spring soup (ssuk-guk) and rice cakes (ssuktteok). Harvest young leaves before the plant flowers; older foliage turns harshly bitter, and a quick blanch tames it.
Medicinally it has a long life as a digestive bitter, taken to rouse appetite and ease bloating and cramping. Dried and aged, it becomes moxa — the herb burned over acupuncture points in traditional Chinese medicine. It carries an old reputation as a dream herb, drunk as tea or tucked under the pillow for vivid dreams, and a longer one as a women's herb used to bring on delayed menses.
A few cautions belong with it. Mugwort contains thujone, as wormwood and sage do, so it is not for large or prolonged doses, and its uterine-stimulant tradition means it is avoided in pregnancy. The pollen is also a leading hay-fever trigger that cross-reacts with ragweed and birch, so anyone allergic to the daisy family should be careful.