Many of us also from time to time talk about a  fourth estate 'the media.
( ( Many ( of us ) ) ( ( ( also ( ( from time ) ( to time ) ) ) ( talk ( about ( ( ( a ( fourth estate ) ) ` ) ( the media ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Many)) (PP (IN of) (NP (PRP us)))) (VP (ADVP (ADVP (RB also)) (PP (IN from) (NP (NN time)) (PP (TO to) (NP (NN time))))) (VBP talk) (PP (IN about) (NP (NP (DT a) (JJ fourth) (NN estate)) (`` `) (NP (DT the) (NNS media))))) (. .)))
Sometimes we talk about a fourth estate, trees.
( Sometimes ( we ( ( talk ( about ( ( ( a ( fourth estate ) ) , ) trees ) ) ) . ) ) )
(ROOT (S (ADVP (RB Sometimes)) (NP (PRP we)) (VP (VBP talk) (PP (IN about) (NP (NP (DT a) (JJ fourth) (NN estate)) (, ,) (NP (NNS trees))))) (. .)))