Aster family (Asteraceae)
Description: This native perennial plant is up to 9' tall and largely unbranched, except for an occasional side stem near the apex bearing an inflorescence. The central stem is dull red or light green, and covered with stiff white hairs. The lanceolate to ovate leaves are up to 10" long and 5" across, narrowing rather abruptly into partially winged petioles about ½-2½" long. There is coarse serration along the margins, and sparse to dense pubescence on the underside of the leaves. Two varieties of Jerusalem Artichoke have been described: Helianthus tuberosus subcanescens has more pubescence on its leaf undersides and it has primarily opposite leaves (except the uppermost), while Helianthus tuberosus tuberosus has less pubescence and it has alternate leaves from the middle part of the plant and upward. Toward the apex are several composite flowers on stalks of varying length. Each daisy-like composite flower is yellow and about 2½-4" across (see Flowerhead Photo). The numerous disk florets are surrounded by 10-20 ray florets. At the base of each flowerhead, there are several series of green bracts that are lanceolate or lanceolate-ovate in shape. There is little or no floral scent. The blooming period occurs from late summer to fall, and lasts about 1½ months. The achenes are grey or brown with longitudinal ridges, slightly downy, and up to 1/3" long. The root system is tuberous or fibrous, and produces long rhizomes. There is a tendency to form colonies by means of vegetative reproduction, particularly in disturbed areas.
Cultivation: The preference is full or partial sun, and moist conditions. The leaves will wilt conspicuously during drought, but this plant recovers readily after significant rainfall. Growth is best when the soil is fertile and loamy, where it may become aggressive. Disease usually doesn't bother this plant until the fall, when powdery mildew on the leaves may become troublesome. While in bloom, it may topple over during a wind storm.
Range & Habitat: Jerusalem Artichoke occurs throughout most of Illinois, except a few counties in southern and NW Illinois (see Distribution Map). It is a fairly common plant, with both native populations and plants that have escaped cultivation. Habitats include moist to mesic black soil prairies, moist meadows near rivers, woodland borders, thickets, borders of lakes, areas along roadsides and railroads, slopes of ditches, and miscellaneous waste areas. This plant is usually more common in disturbed areas in many of these habitats.
Faunal Associations: Bees are the most important pollinators, although the flowers are also visited by bee flies, wasps, beetles, and butterflies. Among the bees, are such visitors as bumblebees, Miner bees, Halictine bees, and Panurgine bees. The flowers are usually cross-pollinated by these insects, and rarely become self-pollinated. The caterpillars of the butterflies Chlosyne nycteis (Silvery Checkerspot) and Chlosyne gorgone (Gorgone Checkerspot) eat the foliage. Similarly, the caterpillars of many moths and other insects feed on various parts of Jerusalem Artichoke, including Pyrrharctia isabella (Isabella Tiger Moth), Papaipema rigida (Sunflower Borer Moth), Papaipema rigida (Rigid Sunflower Borer Moth), and Stibadium spumosum (Frothy Moth). Other kinds of insects that feed on this plant include Publilia concava (Treehopper sp., semi-shaded situations), Melanoplus angustipennis (Spur-Throated Grasshopper sp.), and various beetles. The large nutritious seeds are avidly consumed by various upland gamebirds, songbirds, and small mammals (see Wildlife Table). Large herbivores, such as livestock and deer, may eat the leaves and flowers. Occasionally, the stems are used by muskrats and beavers for their dens or dams.
Photographic Location: The photographs were taken along the rocky slope of a drainage ditch at the Windsor Road Prairie in Champaign, Illinois.
Comments: A better name for this sunflower would be 'Indian Potato' because the native people of North America cultivated and ate the edible tubers, which are produced in substantial quantities. These tubers have fewer calories per gram than the familiar 'Irish Potato' (a South American plant), and are better for diabetics because the carbohydrates and sugars can be assimilated by the digestive tract without insulin. However, the tubers can produce flatulence in some people. This sunflower can be reliably distinguished from other sunflowers by the partially winged petioles, which are ½" or longer on the larger leaves. With the exception of Helianthus annuus (Annual Sunflower), the leaves of Jerusalem Artichoke are wider than other prairie sunflowers in Illinois. It also has stems that are covered with bristly white hairs, unlike Helianthus grosseserratus (Sawtooth Sunflower), which has smooth stems. The green bracts at the base of each flowerhead are usually wider than those of other sunflower species, which typically have linear-lanceolate bracts.