( ( The ( cactus spines ) ) ( ( are ( modified leaves ) ) . ) )
(ROOT (S (NP (DT The) (NN cactus) (NNS spines)) (VP (VBP are) (VP (VBN modified) (NP (NNS leaves)))) (. .)))
The cactus spines are modified leaves.
(ROOT (S (NP (NP (DT The) (NNS spines)) (PP (IN of) (NP (DT a) (NN cactus)))) (VP (VBP help) (SBAR (S (NP (PRP it)) (VP (VBP survive) (SBAR (IN because) (S (NP (NNS spines)) (VP (VB protect) (NP (DT the) (NN cactus)) (PP (IN from) (NP (NNS animals)))))))))) (. .)))