Cashew family (Anacardiaceae)
Description: This native woody shrub is up to 20' tall, but more often 5-6' tall. The new growth of the stems is usually covered with a greyish pubescence. The alternate compound leaves are oddly pinnate, individually consisting of 7-21 leaflets and a central leaf stalk that is conspicuously winged. These compound leaves are up to 2½' long. A leaflet is about 3" long and 1" across. It is ovate or ovate-lanceolate, with smooth margins and an upper surface that is glabrous or slightly pubescent. Some of the upper stems terminate in a panicle of flowers up to 1' long. This panicle is broader at the bottom than the top. The small flowers are yellowish white and individually about 1/8" across. Each flower consists of 5 spreading petals, 5 stamens, and a central pistil. The calyx is divided into 5 triangular lobes that are recurved. Sometimes Winged Sumac is dioecious, with male and female plants. When this occurs, the flowers of the male plants will lack pistils, while the flowers of the female plants will lack stamens. The flowers usually bloom during mid-summer for about 2-3 weeks. Later in the year, they are replaced by dark red drupes that are covered with short acid hairs. Each drupe is about 1/6" long and contains a smooth stone. These drupes persist through the winter, gradually becoming black. The root system consists of a taproot and spreading rhizomes. Sometimes vegetative colonies of plants are created by the rhizomes.
Cultivation: The preference is full or partial sun and mesic to slightly dry conditions. This plant often flourishes in poor soil that is sandy or rocky because of the reduced competition from other plants, but it should develop normally in richer soil as well. The foliage is normally attractive, but occasionally attacked by leaf spot and other kinds of foliar disease. This sumac is less aggressive than Rhus glabra (Smooth Sumac).
Range & Habitat: Winged Sumac is common in southern Illinois, occasional in NE Illinois, and rare or absent elsewhere (see Distribution Map). Habitats include openings in upland forests that are sandy or rocky, woodland borders, sandy savannas, sand prairies, limestone glades, fence rows, and abandoned fields. This is one of the shrubby invaders of sand prairies in NE Illinois. It prefers areas with a history of disturbance, such as fire.
Faunal Associations: The nectar or pollen of the flowers attracts many kinds of insects, especially wasps, flies, and bees. The foliage is a food source for the caterpillars of several species of moths and other insects (see Insect Table). The caterpillars of Pyrrhia umbra (Bordered Sallow) also eat the flowers and drupes. Both upland gamebirds and songbirds eat the drupes during the fall or winter (see Bird Table), and help to distribute the seeds far and wide. Both rabbits and deer browse on the foliage, stems, or bark. In general, the ecological value of sumacs to wildlife is quite high.
Photographic Location: A sandy savanna at Hooper Branch Savanna Nature Preserve in Iroquois County, Illinois.
Comments: The foliage turns red during the fall and is quite attractive. It is easy to identify this species in the wild because the central leaf stalks of the compound leaves are conspicuously winged (see the lower photo). Another distinctive characteristic is the smooth margins of the leaves other Rhus spp. have leaf margins that are serrate or crenate.