I think you meant "when the 'blooms' fell off". If so, what you have left after the petals fall off is the plants ovary where seeds are produced (seed pod) with the stigma attached (the "stem like thing"). These would slowly ripen over the summer, getting fatter, and then drying out in the Fall. Inside would be the seeds. Since hybrids won't come true to seed (even if it produces any) you probably want to deadhead it so the energy can be spent fattening the bulb.

-Helen