The discovery of wells in close proximity to temples in two cultual sites excavated within the Seine-Nord-Europe wide gauge canal project, prompted a recourse to some associated archaeobotanical studies. The carpological data show mainly species of trees, in contrast with sets collected in dwelling sites, where remains from fruit trees and ruderal seeds predominate. In both sites, the carpological and palynological results show the presence of species of trees uncommon in spontaneous groupings and rarely found in archaeological contexts. At Mesnil-Saint-Nicaise, among the numerous trees and shrubs attested by palynology and carpology, we find Box (Buxus sempervirens : leaves and seeds) and Spruce (Picea abies : cone and needles). The case of the broad-leaved Lime tree (Tilia platyphyllos : fruit and flowers) is more complex. If the Lime tree is common in the palynological records, it appears much less so in carpological sets. The high rates of Lime tree pollen found on the site are on the other hand unusual. At Noyon, the carpological collection is composed almost solely of broad-leaved Lime tree fruit, but Buxus , Picea and Tilia are found, among other trees, in the palynological records. The unusual concomitance of species which are not representative of consistent vegetal units raises the question of the deliberate planting of trees in these sacred sites. But the role of these trees was not necessarily a symbolic one, and still requires elucidation. Traduction : Margaret & Jean-louis CADOUX