Green Thumb de Rob Thomas. Encontrei-o procurando por site: plantas de menino goodreads.com assobiando o que me levou a esse cara procurando o mesmo livro que menciona assobios e plantas.
Thirteen-year-old genius Grady Jacobs thinks junior high is a snore. His radical science experiments have earned him plenty of national awards, but not a lot of friends. So when an invitation comes to join the famous scientist, Dr. Carter, in the Brazilian rain forest, Grady is on the next plane to the Amazon. But Grady's ultimate field trip turns ultimately awful when he discovers what Dr. Carter is really up to: he isn't there to save the rain forest -- he is there to destroy it! Can one eight-grade science whiz put a stop to Dr. Carter's evil plans? He can when he is joined by the Urah-Wau tribe of Indians and a supernatural power that no amount of science can ever explain.
O Google Books mostra algumas referências a ele que controlam as árvores geneticamente modificadas com assobios:
I whistle on my lit-zi as he coils to jump again. The tree's branches bend up with all the flexibility possible. The bananas are safely out of his reach.
Há um chefe que está sentindo falta da sua língua, embora eu não consiga entender como ele a perdeu (aparece em uma sacola). O principal vilão é apanhado agarrando-os com videiras e ameaçando-os com a fruta venenosa nas árvores.