Rose family (Rosaceae)
Description: This is a shrub or small tree up to 25' tall and 25' across. It has single or multiple trunks at the base and a densely branched ovoid to globoid crown. The outer trunk bark is more or less gray, falling off in flakes to reveal an orange to orange-red inner bark; it is also somewhat rough and scaly. The bark of most branches is light gray and more smooth, while young twigs and shoots are light green, red, or brown. The latter are also smooth, hairless, and variably thorny. Mature thorns are 1¼–2¼" long, straight, and gray. The alternate leaves are up to 2½" long and 2½" across, broadly ovate or deltate-ovate in outline, and often sharply divided (cleft) into 3 major lobes. When such lobes occur, the terminal lobe is as large or larger than the 2 basal lobes. The leaf margins are shallowly cleft and coarsely toothed. The upper leaf surface is medium to dark green and glabrous, while the lower surface is a more pale shade of green and glabrous. The lateral veins of the leaves extend to both the tips and sinuses of the lobes. The slender petioles are up to 2" long, light green to red, and hairless to slightly pubescent. Corymbs (flat-headed branching clusters) of flowers about 1½-3" across occur occasionally among the leaves on glabrous peduncles. Individual corymbs have 15-50 flowers and pedicels that are green and glabrous. Individual flowers are 3/8–1/2" across, consisting of 5 white rounded petals, a short green glabrous calyx with 5 teeth, 20 stamens with pale yellow anthers (later becoming brown), and a pistil with 5 small styles. The teeth of the calyx are broadly deltate. The blooming period occurs from late spring to early summer (often the latter) for about 1-2 weeks. The flowers have an unpleasant malodorous scent. Fertile flowers are replaced by small globoid pomes about ¼" across. The hairless pomes become orange-red to red at maturity; sepal remnants are absent at their tips. Corymbs of mature pomes have a tendency to droop, often persisting into the winter. Individual pomes contain 5 seeds or less; their flesh is rather dry and thin. The deciduous leaves become some shade of red in the fall. The root system is woody and branching.
Cultivation: The preference is full or partial sun and more or less mesic conditions. Washington Hawthorn adapts to many kinds of soil, including those that contain loam, some clay, rocky material, or sand. Sometimes the leaves are disfigured by hawthorn rust and other disease organisms.
Range & Habitat: Washington Hawthorn is native to southern Illinois, where it is occasional (see Distribution Map). Elsewhere in the state, it may occur as an uncommon escape from cultivation. Habitats consist of open woodlands, savannas, woodland borders, thickets, and fence rows. This small tree or shrub is often cultivated as a landscape plant. Like other Crataegus spp. (Hawthorns), Washington Hawthorn is a pioneer species that benefits from occasional disturbance.
Faunal Associations: The malodorous flowers attract primarily bees and flies. To a lesser extent, wasps, butterflies, and beetles also visit the flowers. These floral visitors seek nectar and/or pollen. Many insects feed on the foliage, flowers, and other parts of Crataegus spp. (Hawthorns). These insect feeders include the caterpillars of the butterfly Satyrium liparops strigosum (Striped Hairstreak), the caterpillars of many moths (see Moth Table), leafhoppers, Glossonotus crataegi (Quince Treehopper), aphids, plant bugs, Corythucha cydoniae (Hawthorn Lace Bug), the larvae of wood-boring beetles, the flea beetle Crepidodera violacea, weevils, and the larvae of gall flies. Vertebrate animals also use hawthorns as a source of food. While it is not preferred, the fruit is eaten by some upland gamebirds and songbirds (see Bird Table); it is also eaten sparingly by such mammals as black bears, foxes, raccoons, skunks, and tree squirrels. These animals distribute the seeds to new locations. Because of its dense branching structure and compact habit of growth, Washington Hawthorn provides nesting habitat for the Yellow-Breasted Chat, Brown Thrasher, and other birds. For the same reason, it provides good cover for many birds and mammals.
Photographic Location: The Arboretum at the University of Illinois in Urbana, Illinois.
Comments: Apparently, the common name derives from an early discovery of this species near Washington, D.C. Of the many Crataegus spp. (Hawthorns) in Illinois, Washington Hawthorn is one of the easier species to identify because of its trilobed leaves. The leaves of other Hawthorns in the state lack the deltate shape and prominent basal lobes. Washington Hawthorn has attractive red fruit during the winter, attractive leaves during both summer and fall, and attractive flowers during the late spring or shortly thereafter. This visual appeal across the seasons is probably the main reason for its popularity as a landscape plant. The availability of thornless cultivars further enhances this popularity.