( This ( ( is ( ( a ( ( mutually beneficial ) relationship ) ) ( where ( ( ( the hyphae ) ( of ( the fungus ) ) ) ( ( ( ( grow around ) ( ( the roots ) ( of trees ) ) ) , ) ( forming ( ( a sheath ) ( of tissue ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBZ is) (NP (NP (DT a) (ADJP (RB mutually) (JJ beneficial)) (NN relationship)) (SBAR (WHADVP (WRB where)) (S (NP (NP (DT the) (NN hyphae)) (PP (IN of) (NP (DT the) (NN fungus)))) (VP (VBP grow) (PRT (RP around)) (NP (NP (DT the) (NNS roots)) (PP (IN of) (NP (NNS trees)))) (, ,) (S (VP (VBG forming) (NP (NP (DT a) (NN sheath)) (PP (IN of) (NP (NN tissue))))))))))) (. .)))
This is a mutually beneficial relationship where the hyphae of the fungus grow around the roots of trees, forming a sheath of tissue.
(ROOT (S (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN beneficial) (NN relationship)) (VP (VBZ exists) (SBAR (WHADVP (WRB when)) (S (NP (NP (DT a) (JJ certain) (NN type)) (PP (IN of) (NP (NP (NN tree) (POS 's)) (NNS roots)))) (VP (VBP need) (S (NP (DT a) (NN fungus)) (VP (VB present) (SBAR (IN in) (NN order) (S (VP (TO to) (VP (VB grow) (ADVP (RB normally)))))))))))) (. .)))
A(n) beneficial relationship exists when a certain type of tree’s roots need a fungus present in order to grow normally.