In message ,
Stephen Henning writes

Hi Doug, You better get you money back on that book.

Rhododendrons are kings of the early flowering shrubs of the Ericaceae
Family (so-called heather family). They are in the Dilleniidae
Subclass and the Ericales Order which includes heaths, heathers,
mountain laurel, and pieris.

Hydrangeas are mid-season bloomers of the Hydrangeaceae Family
(hydrangea family). They are in the Rosidae Subclass and the Rosales
Order which includes cannabis and roses.

More recent botanical opinion places both Ericaceae and Hydrangeaceae in
the asterid clade, the Ericaceae in Ericales, and the Hydrangeaceae in
Cornales (with dogwoods, etc).
--
Stewart Robert Hinsley
http://www.malvaceae.info