Is it a Rhododendron or Azalea?

The answer is Rhododendron. In 1834 confronted with conundrum of evergreen azaleas, botanist George Don abolished Linnaeus’s genus Azalea and lumped it into Rhododendron. Since then botanists have officially discontinued the use of Azalea. While the botanists officially no longer use azalea, gardeners continue to use azalea as a common name.

There are several distinctions made by gardeners to recognize an azalea from a rhododendron.

• Rhododendrons are usually evergreen while azaleas are deciduous, although there are evergreen azaleas.
• Rhododendrons have ten or more stamens, while azaleas have five.
• Rhododendrons have large, paddle-shaped leaves and large, bell- or funnel-shaped flowers borne in terminal trusses. Azaleas have small, elliptical leaves and trumpet- or tubular-shaped flowers at the ends of the shoots.
• Rhododendrons may be erect, growing up to 80 feet high and azaleas are more twiggy, spreading bushes, often reaching a height of no more than 8 feet.

Rhododendron 'Roseum Elegans' in front of West House. photo credit: R. Robert

Most rhododendrons bloom around mid-May. An attractive later blooming rhododendron that can currently be seen in the front of the West Garden on campus is Rhododendron ‘Roseum Elegans’. This lovely lilac-pink bloom is also currently creating great presences in many of the yards in Swarthmore .

Rhododendron 'Roseum Elegans' photo credit: R. Robert

Explore the variety of rhododendrons and azaleas at the Scott Arboretum with over 334 different taxa and over 1000 individual plants.