Rhododendrons, Azaleas, and other heath family shrubs : Rhododendron as a genus comprises more than 1000 species.  They belong to the family Ericaceae, the heath family.  Native species are found worldwide except on the continents of Africa and South America.  Azaleas constitute two sub-genera of the genus.  Numerous hybrids have been developed.  I won't always be able to identify species, hybrid, or cultivar, but wherever readable tags are found, I'll include that information.  Caveat:  tags aren't always correct, and often are taxonomically out of date.  Other members of the family are, confusingly, called laurels.  The confusion is that the term laurel is really most appropriately reserved for members of the Lauraceae family.
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