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Plant Profiles: HORT 2241 Landscape Plants I
Botanical Name: Clethra alnifolia
Common Name: summersweet clethra, sweet pepperbush
Family Name: Clethraceae – summersweet or white alder family
General Description: Clethra alnifolia is native in the Gulf and Atlantic coastal plains primarily in acidic, wet,
boggy habitats. In the landscape they are considered to be tolerant of a wide range of sun, shade, pH and moisture
conditions. However, they perform best in the Chicago area in a well-mulched, moisture retentive soil, in a part
shade condition where they are not exposed to the full afternoon sun. Clethra alnifolia is a lovely, four-season
flowering shrub useful in mixed borders. The summer blooming flowers attract butterflies, bees and
hummingbirds. There are several useful cultivar introductions mostly selected for flower qualities and plant size.
Zone: 4-9
Resources Consulted:
Dirr, Michael A. Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture,
Propagation and Uses. Champaign: Stipes, 2009. Print.
"The PLANTS Database." USDA, NRCS. National Plant Data Team, Greensboro, NC 27401-4901 USA, 2014. Web. 23
Mar. 2014.
Creator: Julia Fitzpatrick-Cooper, Professor, College of DuPage
Creation Date: 2014
Keywords/Tags: Clethra alnifolia, summersweet, clethra, sweet pepperbush, deciduous, shrub, flowering shrub,
summer flowering shrub
Whole plant/Habit:
 Description: Summersweet clethra is a twiggy, dense,
upright oval flowering shrub. Under moist conditions
it can sucker forming a small colony.
 Image Source: Karren Wcisel, TreeTopics.com
 Image Date: June 6, 2012
 Image File Name: summersweet_4327.png
Flower:
 Description: The flowers are the most attractive
feature of summersweet clethra. Flowering midsummer after most other woody shrubs have
bloomed, they attract bees, butterflies and
hummingbirds. The highly fragrant white
(sometimes slightly pink depending on cultivar)
flowers are borne on upright 4-6 inch racemes. They
bloom bottom to top contributing to a long lasting
flowering period of 4-6 weeks.
 Image Source: Karren Wcisel, TreeTopics.com
 Image Date: July 29, 2012
 Image File Name: summersweet_2803.png
Fruit:
 Description: The flowers give way to racemes of
dried 3-valved capsules that persist through winter
and provide a reliable identification feature. The
seeds attract a variety of birds.
 Image Source: Karren Wcisel, TreeTopics.com
 Image Date: March 22, 2009
 Image File Name: summersweet_0471.png
Leaf:
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Description: The leaves are alternate on the twigs,
simple and finely toothed (often entire near the
base). They are medium to dark green in color and
1.5-4 inches in length and about half as wide. It is
important to remember that the leaves are slow to
emerge in spring. It is not dead!
Image Source: Karren Wcisel, TreeTopics.com
Image Date: July 29, 2012
Image File Name: summersweet_2802.png
Leaf:
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Description: The leaves hold green until late October
then change to light yellow, deepening to golden
yellow with a hint of brown, before falling in midNovember.
Image Source: Karren Wcisel, TreeTopics.com
Image Date: October 27, 2012
Image File Name: summersweet_7470.png
Special ID feature(s):
 Description: Everything about this plant is late! It
leafs out late, flowers late, turns fall color late and
holds its fruit late into the following year’s growth
cycle. The persistent fruits are a very useful
identification feature and add to the winter interest
of this plant.
 Image Source: Karren Wcisel, TreeTopics.com
 Image Date: May 14, 2013
 Image File Name: summersweet_4642.png