( It ( ( is ( ( attached ( to ( ( the wall ) ( of ( the ( embryo sac ) ) ) ) ) ) ( by ( a suspensor ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ is) (VP (VBN attached) (PP (TO to) (NP (NP (DT the) (NN wall)) (PP (IN of) (NP (DT the) (NN embryo) (NN sac))))) (PP (IN by) (NP (DT a) (NN suspensor))))) (. .)))
It is attached to the wall of the embryo sac by a suspensor.
(ROOT (S (NP (NP (DT The) (JJ amniotic) (NN sac)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBD was) (VP (VBG sitting) (PP (IN on) (NP (NP (NN top)) (PP (IN of) (NP (DT the) (JJ flat) (NN embryo))))))))) (, ,)) (VP (VBZ envelops) (NP (DT the) (NN embryo)) (SBAR (IN as) (S (NP (PRP it)) (VP (VBZ folds))))) (. .)))