Most people are familiar
with the hydrangea with blue flowers that their grandmother typically grew;
this is the French hydrangea,
Hydrangea macrophylla, and the color actually
depends on soil pH where the flowers would be red in alkaline soil or even
purple in nearly neutral soil.
There are
some varieties that are claimed to be red, but in strongly acidic soils they usually
tend to be closer to purple.
The wild hydrangea,
Hydrangea arborescens, has white flowers, but not as many sterile petalus flowers in
the flat-topped inflorescences except in some improved cultivars. A couple of similar species are ashy
hydrangea, H cinerea, and silverleaf
hydrangea, H. radiata.
While searching throughout much of the southeast for
new species of plants William Bartram discovered oak-leaf hydrangea, Hydrangea
quercifolia Bartram, in Georgia during the 1770's, and his journal, Bartram's
Travels, includes this drawing.
Oak-leaf hydrangea was the best choice when it was named the Alabama
State Wildflower on June 1, 1999, because of its unique native range being
throughout all of Alabama, but then restricted to only parts of the four
adjacent states, plus both North Carolina and South Carolina, and
Louisiana. The state flower of Alabama had been
goldenrod (Solidago) from 1927 to 1959 when it was changed to camellia, but in 1999 is was
also specified as Camellia japonica L., This followed the state tree
being specified as southern longleaf pine, Pinus palustris Miller, in
1997, due there being lots of confusion resulting from southern pine being a
generic lumber term used for several reginal species of pine.
This link gives all of the Official Symbols
and Emblems of Alabama. 
