Amaryllis, Hippeastrum Cultivar

Hippeastrum Herb., is a genus of about 90 species and 600+ hybrids and cultivars of bulbous plants in the family Amaryllidaceae, subfamily Amaryllidoideae. It is native to tropical and subtropical regions of the Americas. The common name "amaryllis" is mainly used for cultivars of genus Hippeastrum.

The photos were taken in a span of 4 days (May 16-May 19), showing still folded blooms up to when the flowers were all opened.

Here's a related spotting of red and white amaryllis - http://www.projectnoah.org/spottings/22577155.