( ( ( ( ( Watch out ) ( for ( poison ivy ) ) ) , ) ( which ( has ( three-leaf clusters ) ) ) ) . )
(ROOT (S (VP (VB Watch) (PRT (RP out)) (PP (IN for) (NP (NN poison) (NN ivy))) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ has) (NP (JJ three-leaf) (NNS clusters)))))) (. .)))
Watch out for poison ivy, which has three-leaf clusters.
(ROOT (S (NP (NN Poison) (NN ivy)) (ADVP (RB typically)) (VP (VBZ has) (NP (NP (CD three) (NNS groups)) (PP (IN of) (NP (NNS leaves))))) (. .)))