Great Rhododendron Rhododendron maximum Linnaeus    Synonyms: Big laurel, Great Laurel, Rosebay.
Kingdom Plantae   >   Division Tracheophyta   >   Class Magnoliopsida   >   Order Ericales   >   Family Ericaceae   >   Genus Rhododendron   

Status:

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).

Description:

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).

Relationships:

Thickets of Great Rhododendron are preferred nesting sites for Canada Warbler.

There are 125 records in the project database.

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Blooming Great Rhododendron found in Garrett Co., Maryland (7/20/2008). Photo by Jim Brighton. (MBP list)

A Great Rhododendron in Garrett Co., Maryland (7/12/2012). Photo by Jim Stasz. (MBP list)

Great Rhododendron in Garrett Co., Maryland (1/13/2020). Photo by William Blauvelt. (MBP list)

Great Rhododendron in Garrett Co., Maryland (7/15/2020). (c) Robert Ferraro, some rights reserved (CC BY-NC). Photo by ptbrnchbob via iNaturalist. (MBP list)

Great Rhododendron growing in Garrett Co., Maryland (2/5/2003). Leaves show drooping and curling that are typical in low winter temperatures. Photo by Boyer and McDowell. (MBP list)

Great Rhododendron in Allegany Co., Maryland (6/27/2015). (c) Wayne Longbottom, some rights reserved (CC BY-NC). Photo by Wayne Longbottom. (MBP list)

Great Rhododendron in Frederick Co., Maryland (7/2/2018). Photo by Robert Warren. (MBP list)

Great Rhododendron in Howard Co., Maryland (6/29/2014). Photo by Jim Wilkinson. (MBP list)

Close-up of Great Rhododendron flowers in Allegany Co., Maryland (6/27/2015). Photo by Bill Hubick. (MBP list)

Great Rhododendron in Harford Co., Maryland (4/16/2016). Photo by Bill Hubick. (MBP list)

Great Rhododendron in Garrett Co., Maryland (3/9/2018). Leaves show drooping and curling typical in low winter temperatures. Photo by Bill Hubick. (MBP list)

Great Rhododendron in Allegany Co., Maryland (4/15/2018). Photo by Wayne Longbottom. (MBP list)

Great Rhododendron in early winter in Harford Co., Maryland (12/6/2015). Photo by Bill Hubick. (MBP list)

Great Rhododendron in Garrett Co., Maryland (7/15/2020). (c) Robert Ferraro, some rights reserved (CC BY-NC). Photo by ptbrnchbob via iNaturalist. (MBP list)

Great Rhododendron in Garrett Co., Maryland (7/22/2015). (c) Emilio Concari, some rights reserved (CC BY-NC). Photo by Emilio Concari. (MBP list)

Great Rhododendron in Frederick Co., Maryland (6/2/2019). Photo by Merry Stinson. (MBP list)


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