( ( ( The ( life cycle ) ) ( of ( all plants ) ) ) ( ( ( is complex ) ( because ( it ( is ( characterized ( by ( alternation ( of generations ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN life) (NN cycle)) (PP (IN of) (NP (DT all) (NNS plants)))) (VP (VBZ is) (ADJP (JJ complex)) (SBAR (IN because) (S (NP (PRP it)) (VP (VBZ is) (VP (VBN characterized) (PP (IN by) (NP (NP (NN alternation)) (PP (IN of) (NP (NNS generations)))))))))) (. .)))
The life cycle of all plants is complex because it is characterized by alternation of generations.
(ROOT (S (NP (NP (DT The) (NN life) (NN cycle)) (PP (IN of) (NP (NNS plants)))) (VP (VBZ is) (ADJP (RB so) (JJ complex)) (PP (RB because) (IN of) (NP (NP (DT the) (NN alternation)) (PP (IN of) (NP (NN generation)))))) (. .)))
The life cycle of plants is so complex because of the alternation of generation.