( Areoles ( ( are ( ( circular clusters ) ( of ( spines ( on ( a cactus ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Areoles)) (VP (VBP are) (NP (NP (JJ circular) (NNS clusters)) (PP (IN of) (NP (NP (NNS spines)) (PP (IN on) (NP (DT a) (NN cactus))))))) (. .)))
Areoles are circular clusters of spines on a cactus.
(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)))))))))) (. .)))