( ( This fungus ) ( ( ( is ( the ( only food ) ) ) ( that ( they ( need ( to eat ) ) ) ) ) . ) )
(ROOT (S (NP (DT This) (NN fungus)) (VP (VBZ is) (NP (DT the) (JJ only) (NN food)) (SBAR (IN that) (S (NP (PRP they)) (VP (VBP need) (S (VP (TO to) (VP (VB eat)))))))) (. .)))
This fungus is the only food that they need to eat.
(ROOT (S (NP (NNP Fungi)) (VP (VBP are) (NP (NP (JJ eukaryotic) (NNS organisms)) (SBAR (WHNP (WDT that)) (S (VP (VP (MD can) (RB not) (VP (VB make) (NP (PRP$ their) (JJ own) (NN food)))) (CC and) (VP (VBP do) (RB not) (ADVP (RB technically)) (VP (VB eat)))))))) (. .)))