Genes with a common function are expected to be under the same evolutionary pressure and hence their underlying species phylogenetic rates are often correlated across long evolutionary times. This phenomenon, previously termed Evolutionary Rate Covariation (ERC), has been studied in yeasts, fruit flies, and mammals, which revealed previously uncharacterized genes interacting with known protein complexes and genetic networks. It has also shown novel evolutionary processes influencing genetic networks. In this study we selected genome sequences from the eudicot (Brassicaceae) and monocot (Poaceae) plant lineages to test the power of the ERC method in plants. Using available functional genomic data in Arabidopsis and Oryza we have investigated whether changes in evolutionary pressure and expression levels, which were largely responsible for the ERC correlations in the animal and fungal kingdoms, are able to explain the ERC correlations in the plant kingdom. As an example, genes involved in the abiotic stress network were examined to find specific genes in the network that have experienced the highest ERC associations. We then used this information to find novel candidate genes that are involved in the stress network. Our analysis suggested the ERC method as a powerful tool to detect novel genes interacting in known plant genetic networks.