*Eucalyptus* is an economically important species, and one of the most common trees found in plantations today. We are currently developing EucGenIE: the *Eucalyptus* Genome Integrative Explorer (https://eucgenie.org), and also the gene expression network comparison tool Complex (http://complex2.plantgenie.org). To enable cross species comparison of gene expression between *Eucalyptus* and other species, such as *Populus tremula*, *Picea abies*, and *Arabidopsis thaliana*, we need to infer a gene expression network from *Eucalyptus* gene expression data. This will enable sharing of information between these species. If a gene of interest for a particular trait has been identified in e.g. *A. thaliana*, Complex can be used to transfer this information into *Eucalyptus*. This will be a valuable resource for *Eucalyptus* genetics, comparative genomics, and even molecular breeding.