Plant@Net has come up with Artemisia verlotiorum, Chinese mugwort, with 54.89% likelihood, Artemisia vulgaris, Mugwort or common wormwood, at 33.45%, and Artemisia princeps, Japanese mugwort, at 10.94%. They have some other Artemisia suggestions at very low likelihood, and no non-Artemesia suggestions. I would think Artemisia vulgaris, but the habit of the one in the UBCBG Physic Garden is so different (upright stems about my height), at least when I photographed it six years ago, and the flower heads here seem to be a different shape. The Artemisia verlotiorum photos I see don't look very convincing. This is in a landscaped area next to an apartment building in my neighbourhood. I had thought the leaves were 3-4cm long and thin, but I see that's only around the flowers. Those leaves are white on the undersides. Lower down on the stems, they are very deeply lobed, three or five lobes, and I didn't notice the undersides. Leaf margins are entire. All the leaves are soft. Stems are reddish-purple, and seemed square with white edges. The leaves had no scent, but I did notice a faint wormwood scent from stroking the flowers.