( ( ( The spines ) ( of ( a cactus ) ) ) ( ( not only ) ( ( prevents ( ( ( water loss ) ( but also ) ) ( animals ( which ( eat them ) ) ) ) ) . ) ) )
(ROOT (S (NP (NP (DT The) (NNS spines)) (PP (IN of) (NP (DT a) (NN cactus)))) (ADVP (RB not) (RB only)) (VP (VBZ prevents) (NP (NP (NN water) (NN loss)) (CONJP (CC but) (RB also)) (NP (NP (NNS animals)) (SBAR (WHNP (WDT which)) (S (VP (VBP eat) (NP (PRP them)))))))) (. .)))
The spines of a cactus not only prevents water loss but also animals which eat them.
(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)))))))))) (. .)))