[~CB]

<sup>"Plants turn out to be secondhand smokers, taking in nicotine from humankind’s tobacco and fumes. And lab tests suggest that slipping a cigarette butt into a plant’s pot sends a temporary surge of nicotine into its leaves.

Researchers sprinkled 100 milligrams of American Spirit tobacco — about an eighth to a tenth of a cigarette — onto the soil of potted peppermint plants. Nine days later older leaves carried roughly fivefold the background level of the leaves’ nicotine, Dirk Selmar of Technische Universität Braunschweig in Germany and his colleagues report April 7 in the journal Agronomy for Sustainable Development.

Nicotine levels spiked also in peppermints closeted with fumes from 11 cigarettes smoked in two hours.

“From a food safety point of view, there is no reason to panic,” Selmar says. He intended the research to help chase down sources of unexpected nicotine in herbal teas and spices despite the European Union’s 2009 ban on nicotine pesticides. Smoking farmers and processors could contribute, in part at least, to the rogue nicotine, Selmar concludes."</sup> Source:"https://www.sciencenews.org/blog/science-ticker/plants-suck-nicotine-nearby-smokers"


My question is... How exactly does plants do that? And why?

[chris]

Nicotine is a plant alkaloid (chemical) that plants synthesise naturally as a form of insecticide. The same nerve-stimulating effects that render nicotine addictive to humans are lethal for insects. Caffeine is similar.

It's actually unsurprising that plants should have mechanisms for concentrating chemicals like caffeine and nicotine in their leaves, because leaves are the most vulnerable structures prone to herbivory. And even though a given plant may not be able to make its own nicotine, the transport systems that already exist in the plant for moving molecules around will readily translocate chemicals like nicotine.