( D ( -RRB- ( ( ( ( At ( ( ( sexual maturity ) , ) ovaries ) ) and ) ( testes ( ( produce ( diploid gametes ) ) ( by meiosis ) ) ) ) . ) ) )
(ROOT (S (LST (JJ D)) (-RRB- -RRB-) (S (PP (IN At) (NP (NP (JJ sexual) (NN maturity)) (, ,) (VP (VBZ ovaries))))) (CC and) (S (NP (NNS testes)) (VP (VBP produce) (NP (JJ diploid) (NNS gametes)) (PP (IN by) (NP (NNS meiosis))))) (. .)))
D) At sexual maturity, ovaries and testes produce diploid gametes by meiosis.
(ROOT (S (NP (NP (JJ Sexual) (NN reproduction)) (PP (IN with) (NP (NNS gametes) (CC and) (NN fertilization)))) (VP (VBZ produces) (NP (JJ diploid) (NN sporophyte))) (. .)))