Landscape heterogeneity is now widely recognized as a key determinant of biodiversity. Defined by its composition (amount and diversity of habitats) and configuration (spatial arrangement of habitats), landscape heterogeneity is a fundamental concept in landscape ecology. Traditionally measured as the amount or surface area of semi-natural habitats in agricultural landscapes, the growing awareness that “the matrix matters” for ecological processes has resulted in the consideration of the agricultural mosaic itself. Indeed, the agricultural mosaic can be viewed as a mosaic of cropped and ephemeral habitats of varying quality, depending on agricultural practices and, contributing to spatial landscape heterogeneity. In addition, agricultural landscapes are highly dynamics. Temporal changes occur from fine-scale (i.e. within a season) to long temporal scale (i.e. over decades). In the first part, I will present the spatio-temporal heterogeneity of agricultural landscapes as well as the recent conceptual framework towards a more functional view of landscape heterogeneity. In the second part, I will illustrate these concepts through three studies I conducted on plant diversity in agricultural landscapes. To conclude, I will underline the need to integrate landscape issues in biodiversity management and conservation strategies.