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Scientific name: Rhododendron spp.

Rhododendron is a genus of 1,024 species of woody plants in the Heath family (Ericaceae), either evergreen or deciduous, and found mainly in Asia, although it is also widespread throughout the highlands of the Appalachian Mountains of North America.

Rhododendrons exhibit an enormous diversity of size and shape, from prostrate ground covers growing no more than a few inches high to trees more than 100 feet tall. Between the prostrate alpine forms and large trees are a variety of shrubby forms in all shapes and sizes. Leaf sizes range from less than 1/4 inch to over three feet long, and they also appear in a variety of shapes: rounded, lance-shaped, and elliptical. The flowers may be white, red, pink, yellow, approximate blue, purple, magenta, orange, and shades and mixtures of most of these colors. There is diversity, too, in bark texture and color. And while March, April, and May represent the peak months for flowering, some rhododendrons can flower as early as January in an ideal climate and others as late as August. The actual beauty of many is supreme–in flower, in decorative new growth, in foliage, in bark, in structure, and even in fall color, particularly with deciduous azaleas.

Rhododendron prunifolium
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Rhododendron and azalea species are found growing in the wild from the arctic region to the tropics. Regions suitable for growing rhododendrons and azaleas are those that have naturally acidic soils, adequate water availability, moderate humidity and winds and lack of temperature extremes.

Comparing Rhododendron and Azalea plants

The Rhododendron plants are usually evergreen and those labeled Azalea plants are deciduous.
• 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. Still some rhododendrons, called lepidoes have small leaves and small flowers and some rhododendrons are naturally miniature have miniscule leaves and flowers. It is true that all azaleas have small leaves compared to the large leaved rhododendrons, the elepidotes.

• Rhododendrons are erect, growing up to 80 feet high, while Azaleas are more twiggy, spreading bushes, usually reaching a height of no more than 8 feet.

• Both Rhododendrons and Azaleas provide fragrant blossoms in an array of colors – from pure white and light pastels to brilliant orange and gold to purple and red. Some blossoms change color over time or are marked with contrasting colors.

More on Trees and Shrubs in Lewisboro

Lewisboro was once entirely forested except for patches of open field caused by fire and wetlands and ponds which were expanded by beaver dams. Although it is hard to believe, by 1800 most of Lewisboro’s forests had been cut down and replaced by farms. In 1820 so many trees had been cleared that there was no shade anywhere along the route from Boston to New York.[1] But by the mid-1800’s farming here became uneconomical and as farms were abandoned, the forests began to re-grow. Today, 70% of New York is once again forest, what some call ‘the great environmental story of the United States’[2]. These new forests provide us with beauty and recreation, clean air and water, flood control, erosion prevention, carbon sequestration, cooler temperatures and habitat for other plants, insects, birds and other wildlife.

[1] Cronon, William. Changes in the Land. Macmillan, 1983.

[2] An Explosion of Green. B. Mckibben. Atlantic Monthly 275 (April 1995): 61-83.