He focuses on one of the two phases to their life cycle. In the first phase, the sporophyte is the diploid generation—that is with two similar sets of chromosomes--that undergoes meiosis to produce cells called spores. Each spore divides forming a single set of chromosomes (haploid) --the gametophyte--which produces the sperm and egg cells.
Proper seed development depends on genes from the embryo and endosperm and from genes from the maternal embryo sac and sporophyte. Using maize, Evans is developing tools for identifying genes that are required for normal embryo sac development and function. He is also investigation the factors that prevent maize and it’s wild cousin teosinte from cross pollinating, and he is identifying genes important for gametophyte function.