The Napoleonic regime built up an ambitious public policy favoring horticulture, despite the challenge it posed to reforestation, to continue the planting of trees along public roads and paths, a practice undertaken by the Monarchy since 1720. This involved the creation of a significant "horticultural machine", with a hierarchical network of public nurseries, in which the dynamics of acclimatization, selection, and distribution of seedlings and tree plants were articulated. Whilst malfunctions affected this horticultural system they did not prevent spectacular successes.