Clethra alnifolia is a rhizomatous shrub with aerial stems from 1 to 3 m tall. Leaves are simple, alternate, and bear stellate hairs; petioles are short, 5–10 mm long; leaf blades are obovate to oblong, 5–10 cm long, with relatively blunt apices, cuneate (wedgelike) bases, and margins that are entire toward the base but finely serrate above the middle; venation is pinnate with secondary veins that extend to leaf margins. Stipules are lacking. Flowers are borne on erect terminal racemes that may be solitary or accompanied by additional racemes terminating few-leaved branches arising from upper nodes. Raceme axes and pedicels are minutely stellate-pubescent; individual flowers are subtended by deciduous bracts; these bracts are longer than the flower buds and therefore prominent before anthesis, but they are soon overtaken by the open flowers, and by full anthesis most bracts have been shed. Flowers are perfect (bisexual), radially symmetric, mostly 5-merous, and pungently sweet-fragrant, appearing from midsummer to late summer. Sepals are persistent, connate only at their base; petals are separate or slightly fused at their base, white or rarely pink, more or less oblong and slightly concave, especially toward their tips. There are 10 stamens present in two whorls; In the Wild Sweet Pepperbush inhabits acidic swamps and moist woods, where it may form extensive colonies that expand via rhizome growth. Ease of propagation and its rhizomatous habit make it a useful element in riparian restoration projects. Flowers are visited by a wide variety of bees and butterflies, the former presumably collecting both pollen and nectar, the latter, just nectar. In addition to cross-pollination by insect visitors, published observations indicate that the flowers are also capable of self-pollination. Where to See It Sweet Pepperbush is found in the coastal plain and outer piedmont of Virginia. As a species it ranges from Nova Scotia and Maine southward to Florida and eastern Texas; seldom found far inland, it is largely restricted to the coastal plain physiographic region of the southern states. Clethra alnifolia anthers invert as buds open and, thus, anther bases appear to be terminal in open flowers; anthers dehisce by pores, and pollen grains are shed singly (not as tetrads). Pistils are composed of three carpels; three stigmas join to form a common style above the three-lobed ovary. Fruits are three-valved capsules containing numerous small seeds.
Copyright © 2015, Virginia Native Plant Society. This article first appeared in Virginia Native Plant Society Brochure (2015), 1-2.
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Hayden, W. John. "2015 Virginia Wildflower of the Year: Sweet Pepperbush, Clethra alnifolia." Virginia Native Plant Society Brochure, 2015, 1-2.