"long" or "to grow" radical in Chinese characters (Kangxi radical 168)
镸 is a component form of 長, which depicts an old person with long hair using a cane to walk.
《說文》：“長，久遠也。从兀，从匕。兀者，高遠意也。久則變化。亾聲。●者倒亾也。，古文長；，亦古文長。”