http://en.wikipedia.org/wiki/Hippeastrum The above link, plus the link that Ed posted, suggests that the trade name "Amaryllis" most often refers to Hippeastrum and includes the many colorful hybrids we have grown to love. True Amaryllis comes in one form. What you have a photo of is Hippeastrum.
Not exactly. The genus Amaryllis is now restricted to two southern African species. There are many different cultivars of Amaryllis belladonna in a wide variety of flower colors ranging from white to almost red. The New World species that are commercially sold as Amaryllis are now in the genus Hippeastrum. What you have is a Hippeastrum hybrid. Botanically, the differences between the two genera are most obvious in the form of the bulb coat and the seeds.
