( Then ( ( a ( haploid gametophyte ) ) ( ( produces ( ( haploid gametes ) ( via mitosis ) ) ) . ) ) )
(ROOT (S (RB Then) (NP (DT a) (JJ haploid) (NN gametophyte)) (VP (VBZ produces) (NP (NP (JJ haploid) (NNS gametes)) (PP (IN via) (NP (NNS mitosis))))) (. .)))
Then a haploid gametophyte produces haploid gametes via mitosis.
(ROOT (S (NP (DT The) (JJ haploid) (NN gametophyte)) (VP (VBZ produces) (NP (NNS gametes)) (PP (IN through) (NP (NNS mitosis)))) (. .)))