Bittersweet family (Celastraceae)
Description: This native plant is a shrub or small tree up to 25' tall. It produces ascending branches sparingly to occasionally. The central trunk and/or larger branches are covered with a thin gray bark that is slightly rough. Smaller branches are dull green with thin vertical stripes of gray bark, while young shoots are entirely green. Young shoots or small branches can be terete (round in cross-section) or 4-angled. Pairs of opposite leaves develop along young shoots and smaller branches; they are up to 4½" long and 2" across. The leaves are ovate to narrowly ovate and finely serrated or crenate. The upper surface of each leaf is dark green and hairless, while the lower surface is pale green and finely pubescent. At the base of each leaf, there is a slender petiole about ½" long. During the fall, the leaves become yellow or red.
Small forking cymes of 7-20 flowers develop from the axils of current or former leaves. Each flower is about 1/3" across, consisting of 4 spreading petals, 4 sepals, 4 short stamens with yellow anthers, and a pistil with a short stout style. The petals are reddish purple and oval in shape, while the smaller sepals are greenish purple and oval. The blooming period occurs from late spring to early summer and lasts about a month. The flowers are replaced by 4-lobed seed capsules that become mature during the fall. At this time, each seed capsule splits open into 4 parts to expose 4 fleshy red arils (fruits) that each contain 2 seeds. The seed capsules are light pink or pale purple with a smooth surface; they later become more dark-colored. The seeds are light brown with a smooth surface. The root system consists of a taproot. This woody plant reproduces by reseeding itself.
Cultivation: The preference is dappled sunlight to light shade, moist to mesic conditions, and a fertile loamy soil.
Range & Habitat: Eastern Wahoo has been found in most counties of Illinois; it is occasional throughout the state (see Distribution Map). The epicenter of this woody plant's distribution is the lower Midwest. Habitats include moist to mesic woodlands, shaded to partially shaded riverbanks, woodland borders, wooded slopes, small openings in wooded areas, and thickets. This species is typically found in Maple-Basswood, Maple-Beech, and similar deciduous woodlands. It doesn't appear to spread into disturbed areas to the same extent as some invasive Euonymus spp. from Eurasia.
Faunal Associations: The flowers attract small bees (mostly Halictid bees), miscellaneous beetles, and various flies. Among these insects, the flowers are especially attractive to flies, possibly because the color of their petals resembles carrion or other rotting material. Typical fly visitors include Syrphid flies, Flesh flies (Sacrophagidae), Muscid flies, Blow flies (Calliphoridae), and Anthomyiid flies. These insects feed primarily on nectar. The foliage of Eastern Wahoo is eaten by the caterpillars of the moths Ectropis crepuscularia (Saddleback Looper), Herpetogramma thestealis (Pyralid Moth sp.), and Yponomeuta multipunctella (American Ermine Moth). A recently introduced moth, Pryeria sinicia (Euonymus Leaf Notcher), has been observed along the East Coast of the United States, but it hasn't spread to Illinois thus far. Other insects that feed on Euonymus spp. include Otiorhynchus sulcatus (Black Vine Weevil) and Unaspis euonymi (Euonymus Scale). The red fruit of Eastern Wahoo is not especially popular with birds. However, the Northern Flicker, Brown Thrasher, Catbird, Eastern Bluebird, Cardinal, and Eastern Towhee eat the fruit to a limited extent (Source: Morton Arboretum). These birds help to spread the seeds in the fruits to new locations. White-Tailed Deer browse on the leaves and young shoots.
Photographic Location: The northern edge of Busey Woods in Urbana, Illinois.
Comments: Other common names of this species are 'Spindle Tree' and 'Eastern Burning Bush.' The various Euonymus spp. in Illinois are either woody vines or small trees/shrubs. Some of these species are native, while others are Eurasian. In general, they have small flowers with 4-5 petals and odd little fruits with 4-5 lobes. Some of these species, including Eastern Wahoo, have unusual bark that is green, striped, and/or winged. Eastern Wahoo can be distinguished from other erect Euonymus spp. by the following combination of characteristics: 1) its leaves have petioles exceeding ¼" in length, 2) the leaves are finely pubescent on the underside, rather than hairless, 3) the bark of some branches is green with tan or gray vertical stripes, 4) the outer sides of the seed capsules are smooth, rather bumpy or warty, and 5) the flowers have 4 reddish purple petals. With respect to the last characteristic, other Euonymus spp. in Illinois have flowers with 5 petals, or their petals are white, green, or yellow.