( ( By ( that definition ) ) ( , ( technically ( ( any plant ) ( ( could ( be ( considered ( to ( ( ( be ( a weed ) ) , ) ( ( as long ) ( as ( it ( is ( growing ( where ( people ( ( do n't ) ( want ( it ( to grow ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (PP (IN By) (NP (DT that) (NN definition))) (, ,) (ADVP (RB technically)) (NP (DT any) (NN plant)) (VP (MD could) (VP (VB be) (VP (VBN considered) (S (VP (TO to) (VP (VB be) (NP (DT a) (NN weed)) (, ,) (SBAR (ADVP (RB as) (RB long)) (IN as) (S (NP (PRP it)) (VP (VBZ is) (VP (VBG growing) (SBAR (WHADVP (WRB where)) (S (NP (NNS people)) (VP (VBP do) (RB n't) (VP (VB want) (S (NP (PRP it)) (VP (TO to) (VP (VB grow)))))))))))))))))) (. .)))
By that definition, technically any plant could be considered to be a weed, as long as it is growing where people don't want it to grow.
(ROOT (S (NP (NP (NNS Plants)) (SBAR (WHNP (WDT that)) (S (VP (VBP grow) (SBAR (WHADVP (WRB where)) (S (NP (PRP you)) (VP (VBP do) (RB n't) (VP (VB want) (NP (PRP them)))))))))) (VP (VBP are) (VP (VBN called) (NP (NNS weeds)))) (. .)))