unkraut or worldwide weed

Surviving the past three winters or so, exposed on the balcony, is a venerable old dandelion (Taraxacum officinale) that one day took up root in this since vacated pot. Even after the monk and botanist Gregor Mendel developed the theory of heredity by selecting for visible and measurable traits over successive generations of peas in a pod in the mid-1800s, many people still held to the once popular theory of spontaneous generation: that flies and worms and other vermin did not have natural parentage and arose out of the slime and muck and generally poor house-keeping.
I wonder if people believed the same about weeds (Unkräuter)—although the concept of weeds in gardening is a relatively new invention and heretofore certainly was not applied to the dandelion. The common and polite name for the flower does not have anything to do with its yellow bloom that some might find reminiscent of a lion's mane, but it is rather a corruption of the French for teeth of the lion, for its jagged leaves. That seems a little less iconic, but the modern name is a euphemism (Greek for “a holy silence”) its old reputation, when still considered Kraut—an herb with medicinal properties, rather than some worthless, old Unkraut. Originally, the plant was called in French pissenlit—wet the bed—because it was a diuretic, and native to all parts of the earth, there were many colourful, local variations on that phenomena. Being the lingua franca, it sought to clean up the world's vocabulary a bit. A similar sort of mannerly substitution occurred in English by inventing the words donkey and rooster to avoid saying something offensive. Tending a few weeds should cause no alarm, no matter the company.