Isto é As Cavernas de Lótus , de John Christopher, publicado em 1969.
Está empatado com A Cidade de Ouro e Chumbo por meu trabalho favorito de Christopher (também conhecido como Samuel Youd).
A imagem de capa mais comum foi esta:
Por Goodreads:
Fleeing the claustrophobic artificiality of the Moon Bubble, 14-year-olds Marty & Steve illegally reconnoiter-the long-abandoned 1st Station &, following a clue in the journal of "never recovered" Andrew Thurgood, plunge their mechanical crawler into a fragrant, fertile warren of caves. There the enveloping moss & branches, the moving, metamorphosizing leaves & undergrowth are all part of one gigantic sentient Plant which has also provided, for the surviving Thurgood, a lush earth-like orchard & an orchestra tree programmed to play his favorite (now 70-year-old) tunes. The Plant will pamper them until, like the Odyssey's lotus-eaters, they'll relinquish all thoughts of escape. Marty's fight against euphoria, which involves arousing the lethargic, Plant-worshipping Thurgood, is quickly told--more quickly than the Lunarians-at-school episode at the beginning.