The researchers trapped pea plants in glass chambers with ether, soaked roots of the sensitive plant and seedlings of garden cress in lidocaine and even measured the electrical activity of a Venus fly trap’s cells. An hour or so later the plants became unresponsive. The seedlings stayed dormant. And the Venus fly trap didn’t react to a stimulus similar to a bug crawling across its maw. Its cells stopped firing.

When the dope wore off, the plants returned to life, as if something had hit pause — almost like they were regaining consciousness, something we typically don’t think they possess. It’s all so animal-like.

“How organisms are perceiving the environment or responding or adapting are based on some very similar principles,” Dr. Baluska said.

Researchers already knew that anesthetics with different chemical structures or elements all seem to halt pain, consciousness or activity in plants and animals — even bacteria. But how they render us unconscious or how so many different kinds physically act on the human nervous system still elude us after more than a century of use. Some bind to receptors to turn off activity. But this can’t explain them all.

Under anesthetics, the physical properties of cell membranes change, becoming more flexible. Apply pressure to the cells, this effect is reversed and the anesthetic wears off. This suggests that something simple, like what is physically happening to a cell’s membrane, may be the common denominator explaining anesthetics’ effects across the plant and animal kingdoms, Dr. Baluska and colleagues suggest.