Dessins D'Enfants and Hubbard trees

We show that the absolute Galois group acts faithfully on the set of Hubbar d trees. Hubbard trees are finite planar trees, equipped with self-maps, wh ich classify postcritically finite polynomials as holomorphic dynamical sys tems on the complex plane, We establish an explicit relationship between ce rtain Hubbard trees and the trees known as "dessins d'enfants" introduced b y Grothendieck, (C) 2000 Editions scientifiques et medicales Elsevier SAS.