( ( Once mature ) ( , ( ( the plant ) ( ( reproduces ( by ( growing ( ( ( a flower ) , ) ( which ( is ( ( the ( sexual part ) ) ( of ( ( the plant ) ( that ( produces seeds ) ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Once) (S (VP (VBP mature)))) (, ,) (NP (DT the) (NN plant)) (VP (VBZ reproduces) (PP (IN by) (S (VP (VBG growing) (NP (NP (DT a) (NN flower)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (NP (NP (DT the) (JJ sexual) (NN part)) (PP (IN of) (NP (NP (DT the) (NN plant)) (SBAR (WHNP (WDT that)) (S (VP (VBZ produces) (NP (NNS seeds)))))))))))))))) (. .)))
Once mature, the plant reproduces by growing a flower, which is the sexual part of the plant that produces seeds.
(ROOT (S (NP (NP (DT A) (NN method)) (PP (IN of) (NP (NP (JJ sexual) (NN reproduction)) (SBAR (WHNP (WDT that)) (S (VP (VBZ occurs) (PP (IN in) (NP (NNS plants))))))))) (VP (MD can) (VP (VB be) (VP (VBN described) (SBAR (IN as) (S (NP (NNS seeds)) (VP (VBP are) (VP (VBN produced) (PP (IN from) (NP (NP (DT the) (NN flower)) (PP (IN of) (NP (DT the) (NN plant)))))))))))) (. .)))