(Linn. Sp. Pl. (1753) 392)
by Susannah G. Cooper
R. maximum photographed by Robert J. Mckenzie
Kingdom: Plantae
Class: Dicotyledones
Order: Ericales
Family: Ericaceae
Subfamily: Rhododendroidae
Tribe: Rhododendreae
Genus: Rhododendron
Seed: The R. maximum's seed is winged and oval. It is brown to red-brown and finely ribbed[1].
Seedling: The hypocotyl is smooth and whitish-green. The cotyledons are about 3mm long with 4-6 hairs along the margins. The epicotyl is a few branched hairs. The first foliage leaf is also a few branched hairs[1].
Mature Plant: R. maximum is a shrub which is mostly found below 1000m along shaded stream or in wet wooded areas. It typically grows 1.22-3.66m high, but has known to grow up to 12.20m. R.. maximum typically grow in dense thickets. The leaves are about 9-20cm long and 2.5-7cm wide and are lanceolate or oblong lanceolate shaped. The topside of the leaf is a shinny dark or olive green color. The underside has thin layer of hairs[2]. The leaves are slightly curled; during a drought or extreme cold, the leaves "tightly roll into cylinders" [3]. The twigs are stout. In the first year, the twigs are dark green. However in the second year, the twigs are red. The flower bud is terminal; it is yellow-green and 25-35mm long[3]. The flowers bloom from May to August with inflorescences which contain 12-30 flowers. The flowers are funnel- or cup-shaped; its size ranges from about 2.3-3.1cm. The flower coloration is white, pink, light rose, or purple. The flower commonly has 10 stamens, but is known to have 8-12[2]. The capsule is ovoid, about 9-12mm in length, and is a dark reddish-brown color[3].
Area |
Status |
Source |
| North America: Canada; continental U.S. | Yes | Duncan and Duncan 1988 |
| eastern North America: U.S. east of the Mississippi; Ontario, eastern Canada | Yes | Duncan and Duncan 1988 |
| southern U.S: AL, AR, DE, DC, FL, GA, KY, MD, NC, SC, TN, VA, WV | Yes, usually found in mountainous regions | Swanson 1994 |
| southern Appalachian states: AL, GA, KY, MD, NC, SC, TN, VA, WV | Yes | Swanson 1994 |
| Coastal Plain | No | Duncan and Duncan 1988 |
| Piedmont | Yes | Duncan and Duncan 1988 |
| Blue Ridge | Yes | Wofford 1989 |
| Blue Ridge- Great Smoky Nat'l Park | Yes | Wofford 1989 |
| Ridge and Valley | Yes | Duncan and Duncan 1988 |
| Cumberland Plateau | Marginally | Duncan and Duncan 1988 |
| Central Arch | ? | - |
| Georgia | Yes | Mellinger 1984 |
| Georgia, Clarke County | No | Mellinger 1984 |
| Georgia, Clarke County, Sam's Farm | No | Mellinger 1984 |
R. maximum is a native plant to North America; it grows all along the Appalachian mountains: from Georgia to New England. R. maximum is even found in Quebec and Novia Scotia. Peter Collinson, an English Quaker, and John Bartam,a Pennsylvania farmer, introduced this species England in 1736. They sold the plants in London to gardening enthusiasts in order to fund more expeditions of plants in American Later, Bartam was to become the King's botanist in America. . R. maximum was not popular in England because is was not very decorative due to the small flowers[6].
Please refer to cultivation section on genus page.
[1] Hedgaard, J. Morphological Studies in Genus Rhododendron: Dealing with Fruits, Seeds, Seedling and their Associated Hairs. G. E. C. Gads Publishing House: Copenhagen.
[2] Davidian, H. H. 1982. Rhododendron Species Vol III: Neriiflorum- Thomsonii, Azaleastrum and camtschaticum. Timber Press: Portland. p.167-168
[3] Swanson, R .E. 1994. A Field Guide of the Trees and Shrubs of the Southern Appalachians. John Hopkins University Press: Baltimore. p.303-306.
[4] Duncan, W. H. and Duncan, M. B. 1988. Trees of the Southeastern United States. University of Georgia Press: Athens, GA. p.220.
[5] Mellinger, M. B. 1984. Atlas of Vascular Flora of Georgia. Studio Designs Printing: Milledgeville, GA.
[6] Street, J. 1987. Rhododendrons. Globe Pequot Press: Chester, Connecticut. p.13-18.
