Guidebook to Avalable Rhododendrons
For anyone wanting to see a book that is profusely illustrated with species, and hybrid (cultivar) rhododendrons I would recommend, the now out-of-print, "Greer's Guidebook to Available Rhododendrons" by Harold E Greer. There are several editions, which can be found on line on ebay, amazon, etc. This is not a key that will tell you what species, or hybrid, you are looking at, but it will show the variety of hybrid varieties exist, especially in gardens and urban areas.
