When a 2,000-year-old corpse surfaced in a Danish peat bog in 1950, it was so well-preserved that the man appeared to have perished only recently. Judging from the noose around his neck, the man was probably strangled. There was much in the find to interest anthropologists, but what caught Richard Mabey’s attention was the contents of the stomach: weeds. The man’s last meal included generous servings of knotgrass, bindweed, dock and other such nefarious flora.

Mabey populates his smart new book, “Weeds,” with many such strange surprises. Our battle against botanical evildoers reached a fevered pitch in the Middle Ages, a time when sparrows could be excommunicated and weevils put on trial for ravaging a church’s vineyards. While no such trials were carried out against thornapples or darnel (to my great disappointment), medieval herbals — texts describing medicinal uses of plants — were heaped with false accusations. Cyclamen, according to a 16th-century spinner of horticultural nonsense named John Gerard, could bring on a miscarriage if a pregnant woman stepped over it. He constructed lattices over his cyclamen to protect female visitors to his garden.

The history of our most pernicious plants is another version of our own history; after all, some of them gain traction by following us around. Mabey notes how wispy seeds of ragwort can drift into a rail car, hang in the air and drift out at the next stop. Hogweed seeds floated down London’s canals, eventually colonizing Scottish riverbanks. After World War II, such a profusion of thistles and creeping buttercup grew on bombsites that people wondered if the Germans had dropped them, too.

In fact, Mabey argues, weeds flourish in the wake of destruction. He makes a case for allowing invasive plants to remain in cities, which represent a relatively new kind of ecology anyway, one to which tougher, more aggressive plants might be well-suited. East London street artists have embraced this idea, creating an urban florilegium by sneaking around to stencil the names and descriptions of weeds on the sidewalks from which they spring. And in the wild, Mabey proposes that exotic species be treated like naturalized citizens, granted a conditional visa if they can become a useful part of the ecology without destroying it.

Mabey is at his best when he takes us along on his own weedy adventures. He once joined an urban expedition to catalog the vegetation sprouting in London’s dumps. He picked his way through burning rubber, discarded cows’ intestines and endless fetid piles of kitchen waste. Out of this mess grew the strangest botanical species: marigolds and coriander, deadly nightshades and cocklebur. Weeds are not just around us, he declares, they are in us and of us. Gregarious, adventurous, prolific and profane — “the species they most resemble is us.”

‘Weeds: In Defense of Nature's Most Unloved Plants’ by Richard Mabey. Ecco. 324 pp. $25.99 (Ecco/Ecco)

Amy Stewart is the author of “Wicked Bugs: The Louse That Conquered Napoleon’s Army & Other Diabolical Insects.“