Great Rhododendron is native to North America from Ontario and Nova Scotia south to Ohio, Alabama and Georgia. It is most concentrated in the southern Appalachian Mountains, where it commonly grows in dense thickets that dominate the understory. Its habitat is mainly damp woods, swamps, protected ravines, and along creeks and pond margins. In Maryland it occurs in the mountains of the western part of the state, but is also present in the upper midland and in Cecil County (Fernald, 1950; Brown and Brown, 1972).
Great Rhododendron is an evergreen shrub with dark green, very thick leaves. Although evergreen and broad, the leaves are adapted to the cold temperatures of the Appalachians. In low temperatures, the leaves droop and curl. The drooping is thought to protect the delicate, only partially winter-functional, photosynthetic apparatus from damage due to direct, intense winter light; and the curling is thought to protect cell membranes from rupture as temperatures climb from night-time lows to higher, daytime levels (Nilsen, 1990).
Thickets of Great Rhododendron are preferred nesting sites for Canada Warbler.
There are 189 records in the project database.
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