In the garden of the English language, “root” is a word in fairly fresh soil. Though the word itself has a very long history, it came into our language only recently, brought by Vikings about 1000 years ago. The word “root” came into Old English from Old Norse, the language of the Vikings, as rot, with a long ‘o’ (/o/, roughly like the ‘o’ in Spanish burro).
Even before “root” was adopted into Old English, the language already had a form cognate (that is, a word originating from a common verbal ancestor) to rot—the word wyrt. All of the Germanic words for plant/root descend from the Proto-Indo-European noun which can be simply rendered as *wrod or, in another form, *wrd, from which both rot and wyrt are ultimately derived.
Looking at spotted lungwort leaves, one might assume, falsely if justifiably, that “-wort” has something to do with “warts.” Actually, “-wort” comes from the aforementioned Old English wyrt, which means “plant.” Therefore “lungwort” literally means “lung-plant” (it is the “lung” and not the “-wort” part that refers to the pattern on the leaves).
A modern-day Swede or Dane might be able to tell you as much intuitively—in Swedish, one of the modern words for plant is ört, comparable to the Danish urt. Both come from an Old Norse urt. So, did Old Norse possess two cognates of the same root, rot and urt? Yes, but only in the same sense Old English did. Just as “root” is a borrowing from Old Norse, so was Old Norse urt a borrowing from Old English wyrt.
There is a third cognate of wrod in English as well. This is the “rad-” element of words such “radical” and “radish.” All words of this rough group are derived, in one way or another, from the Latin radix, “root.” “Radish,” in fact, is a direct borrowing from Latin (the stem, or base form, of the Latin word was radic- with a hard c, changed into a “sh”-sound by the Anglo-Saxon borrowers).
Then how did the word “radical” become a synonym for “extreme” or “divergent”? One might think an adjective meaning “related to roots” would apply to conservative, old-fashioned, or fundamentalist views. Indeed, in post-Classical Latin, when radicalis came into written use, it originally carried the meaning of “primary” or “original.” However, in French, the word’s applications ballooned in number, and it soon came to mean “profound” or “intense”—and from “intensity” to modern “radicalism” the jump seems not too far at all.
While the link between modern-day revolutionaries and a certain red vegetable seems unlikely, the names for both are well rooted in the past.