I’m very familiar with bomb-sniffing dogs.
But I’ve never heard of anything like this before, but it seems that there are some biologists working to develop bomb-detecting plants. They’ve developed proteins that react to TNT that can be placed in practically any plant.
They have already produced plants, in a laboratory setting, that blanch white when TNT is present. Amazing! The goal is to eventually sell them, as cheaper and less conspicuous than other forms of bomb/explosives detection.
(There is the question, though, are there any side-effects, and if so, what are they?)