Clethra alnifolia & Clethra alnifolia 'Ruby Spice'
Common name: Sweet pepperbush, summersweet
Clethra alnifolia, native to eastern North America, is an upright, medium-sized, deciduous shrub noted for producing mid- to late-summer blooms of small, sweetly scented, 5-petalled flowers. Some are white, and some are pink. C. alnifolia is native to woodlands, bogs, and streambanks along the coast from southern Nova Scotia to Maine, and south to Florida, as well as west to Texas. It is an undemanding plant, tolerating everything from full sun to full shade, and is adaptable to dry conditions once it is established. However it does prefer moist, acidic soil. It is generally disease-free.
The flowers of C. alnifolia bloom on new wood (the current year's growth). The fragrant white or pink flowers are bottlebrush-shaped, and appear at the tips of branches. They are attractive to bees, butterflies, and other pollinators. After the blooms fade, dark brown seedpods that resemble peppercorns develop, thus the name sweet pepperbush. These seedpods persist through the winter providing food for birds. C. alnifolia is late to leaf out in spring, sometimes not till the end of May. The serrate, glossy, dark green leaves turn yellow to golden brown in autumn.
The genus name Clethra is from the Greek word 'klethra' meaning alder (a type of tree), and the specific epithet alnifolia means leaves like alder. C. alnifolia leaves look similar to alder leaves. C. alnifolia was described and the name validly published by Carl Linnaeus.
Clethra alnifolia can be found in Bed 27 of the Eastern North America Garden. Twelve were planted there in 1979.
There are a number of cultivars of C. alnifolia. One of them is Clethra alnifolia 'Ruby Spice'. C. alnifolia 'Ruby Spice' is a sport of Clethra alnifolia 'Pink Spire'. It was discovered in 1992, and is noted for its highly fragrant, darker pink flower spikes. C. alnifolia 'Ruby Spice' is hardy, and has a tidy, upright habit. It grows to about 120-180 centimetres (4 - 6 feet) in height.
Clethra alnifolia 'Ruby Spice' can be found in Bed 33A next to the path leading to the Floating Bridge. It was planted there in 2003. It can also be found in Bed 36C near the Bentall Pond.
Text and photos by Kumi Sutcliffe.