In Full Bloom

Here is the same bloom as yesterday, but fully opened.

The scientific name for this plant is Schlumbergera truncata.  The first part of the name is for a collector of cactus Frederic  Schlumberg who lived in on the outskirts of Rouen in southern France.  The namer  of the species was Charles Lemare, and the collector was Allan Cunningham who under the employment of Kew Gardens spent the years between 1814 and 1816 collecting plants from the Rainforest of what is now Brazil.   The second part of the name refers to the fact that the "leaves" are really a segmented trunk, which is botanically called cladodes.

Their specific origin is the Rio de Janeiro.  And they also are pollinated by humming birds.  Like many plants they must be cross pollinated with another plant that isn't closely related.

The best article I could find on the internet discussing this plant is on the blog Plants are the Strangest People.