Artemisia absinthium, the bitter worm‑wood, is a hardy shrub that can pull lead and copper out of old foundations while its essential oils have been used for centuries to treat fevers and stomach aches. Lobelia inflata, the so‑called Indian tobacco, is a low‑lying herb that will grow in contaminated riverbanks and whose alkaloids were once prized for easing asthma and lowering blood pressure. And if you can find the rare alpine “Salix purpurea,” the purple willow, it will soak up arsenic from mine tailings and its bark contains salicylates that can soothe aches – a perfect, if slightly overlooked, match of cleaning and healing.