'Root' shares ancestry with 'radical' (to the root), 'radish,' and 'eradicate' (to uproot).
The part of a plant which attaches it to the ground, typically underground, conveying water and nourishment; the basic cause, source, or origin of something.
From Old Norse rót, borrowed into Middle English (not native Old English) 'rōt,' strongly reinforced by Old Norse 'rót' (root), from Proto-Germanic *wrōt- (root), from PIE *wréh₂ds (root). The same PIE root gave Latin 'rādīx' (root — whence 'radical,' 'radish,' 'eradicate') and Greek 'rhíza' (root — whence 'rhizome'). The initial *w- was lost in most branches but left traces in the Germanic spelling
'Root,' 'radical,' 'radish,' and 'rhizome' all come from the same PIE word *wréh₂ds (root). A 'radical' is someone who goes to the root of things. A 'radish' is literally just 'root' in Latin. To 'eradicate' means to pull up by the roots. Four different forms of the same ancient word for the thing that anchors a plant.