A similar self-sterile white petunia mutant later joined the corn. The female parts of the reproductive system that receive the pollen are normal and will produce seed when pollinated by normal petunia pollen. Obviously these mutants aren't producing the increased yields, for they're not producing any seeds at all. The increased yields come when a normal petunia is treated prior to pollination with kaempferol, the substance that's missing from the sterile pollen. Kaempferol is a small, relatively simple molecule, one of many similar plant molecules called flavonoids.
Flavonoids provide flower petals with color, among other things.
But there's more to the flavonoid story. Although the purpose is uncertain, in stressful situations plants produce more flavonoids. Taylor's work has shown that some of these same flavonoids are also used in reproduction. This implied relationship between plant defense and plant reproduction is something she would like to have a lot of time to think about.