Plant science for plant people.

Taro growing near factories in Bangladesh packed lead into its tissue at close to nine times the concentration in the soil around it. The plants weren't just surviving on poisoned ground; they were stockpiling the metal.

Researchers sampled plants on soil loaded with lead, chromium and cadmium. Para grass was the standout mover. Across nearly all nine metals tested, it carried four to eight times more metal up into its stems and leaves than it held in its roots. That matters because leaves can be cut and hauled off site, taking the metal with them. Sensitive plant, the mimosa, scored 8.15 on that same root-to-shoot measure for lead, and chickweed (Stellaria media) built up chromium at 7.45 times the soil level.

Vetiver grass shows what years of this look like. Planted on contaminated ground at Bien Hoa Airbase in Vietnam and tracked for 55 months, it got steadily better at drawing up cadmium, with uptake rising 2.3-fold over the assessment window. A fire burned off its leaves, the roots survived, and the plant came back stronger. It left chromium and nickel alone, though; those stayed locked in mineral forms deep in the soil.

One note for foragers: factory-edge taro is a cleanup crew, not dinner. The weeds along that fence have been pulling metal out of the ground on their own, and now we know which ones to plant on purpose.