Prairie Crab Apple
Malus ioensis
Rose family (Rosaceae)

Description: This woody plant is a large shrub or small tree about 10-25' tall that has a short trunk up to 1' across and a broad spreading crown. It is moderately to densely divided into crooked branches, short lateral spurs, and twigs. The trunk bark of mature trees is mostly gray, scaly, and thin; the irregular furrows and fissures separating the scales are narrow, shallow, and often reddish brown. Branch bark is mostly gray and more smooth with scattered white lenticels (air pores); sometimes it has a reddish brown tint. Twigs are gray to reddish brown and smooth to slightly pubescent; they also have scattered white lenticels. The short lateral spurs are oriented at a right-angle from their branches; they are similar to the twigs, except they sometimes develop into thorns. Young shoots are light green, terete, and densely pubescent. Alternate leaves occur along the shoots, young twigs, and short lateral spurs; they often appear densely clustered. The leaves are 1–4" long and 1-2" across; they are ovate or oblong-ovate in shape, while their lower-middle to upper margins are crenate-dentate and often shallowly cleft into short irregular lobes. The bases of leaves are rounded to broadly wedge-shaped and entire (both toothless and lobeless), while their tips are obtuse. The upper leaf surface is medium green and glabrous (although short-pubescent when very young), while the lower leaf surface is densely short-pubescent to pubescent and pale green to white. Leaf venation is pinnate. The petioles are –1" long, densely pubescent, and more or less whitened.

Clusters of 2-6 flowers develop from the tips of twigs and short lateral spurs. The pedicels of these flowers are –1" long and densely pubescent. Individuals flowers are 1–2" across; each flower consists of 5 light pink to nearly white petals, a green cup-shaped calyx with 5 teeth, 10-20 stamens with yellow anthers, and a pistil with 5 styles. The widely spreading petals are oval in shape, except they taper abruptly to become narrow at their bases. The calyx and its teeth are pubescent on both the exterior and interior surfaces; the teeth are linear-lanceolate to narrowly triangular in shape. The large flower buds are usually bright pink. The blooming period occurs during the late spring, lasting about 1-2 weeks. The diurnal flowers have a tendency to bloom at about the same time, and they are fragrant. Afterwards, fertile flowers will be replaced by fruits (pomes) that become 1–1" across at maturity; they are subgloboid to globoid in shape, except at their apices and bottoms, where they are indented. Mature fruits are greenish yellow with waxy exteriors, while their interiors are fleshy, firm, and white; each fruit contains up to 10 seeds. The flavor of mature fruits is sour and bitter. The seeds are dark-brown, flattened, and tear-drop shaped. The root system is woody and spreading; it is capable of developing clonal offsets from underground runners, especially when this woody plant has been top-killed by fire or some other catastrophe.

The preference is full or partial sun, moist to mesic conditions, and soil containing loam, clay-loam, or some rocky material. Like other apples and crab apples (Malus spp.), this woody plant is vulnerable to many disease organisms and insect pests. Nonetheless, if conditions are favorable, it can be long-lived, exceeding 50 years of age.

Range & Habitat: The native Prairie Crab Apple occurs in almost all counties of Illinois, where it is occasional (see Distribution Map). Populations of this species have declined because of habitat destruction. It is largely endemic to the midwestern United States (upper Mississippi valley), although widely scattered populations of this species occur further south. Habitats include open woodlands, savannas, thickets, woodland borders, limestone glades, prairies, hill prairies, semi-open areas along streams, edges of pastures and fields, fence rows, and powerline clearances in wooded areas. Prairie Crab Apple requires some disturbance in order to establish itself and thrive, although excessive disturbance will eliminate it.

Faunal Associations:
The value of Prairie Crab Apple to various kinds of wildlife is quite high. The nectar and pollen of the large flowers attract honeybees, bumblebees, and other long-tongued bees; they are probably the primary agents of cross-pollination. Other visitors of the flowers include smaller bees, butterflies, and skippers. A variety of insects feed destructively on the foliage, fruit, flowers, wood, and plant juices of crab apples and apples (Malus spp.), including Prairie Crab Apple. These insect feeders include leafhoppers (Eratoneura hartii, Erythridula dowelli, Erythridula lawsoniana, Typhlocyba pomaria) and such aphids as the Green Apple Aphid (Aphis pomi), Rosy Apple Aphid (Dysaphis plantaginea), Woolly Apple Aphid (Eriosoma lanigerum), and Apple-grass Aphid (Rhopalosiphum oxyacanthae). Other miscellaneous pests include the Apple Red Bug (Lygidea mendax), larvae of the Apple Twig Borer (Amphicerus bicaudatus), larvae of the Flat-headed Apple Tree Borer (Chrysobothris femorata), larvae of the Round-headed Apple Tree Borer (Saperda candida), the Apple Curculio (Anthonomus quadrigibbus), Apple Flea Weevil (Rhynchaenus pallicornis), and Apple Maggot (Rhagoletis pomenella). The Insect Table has a more complete list of these species.

The larvae of a large number of moths also feed on various parts of these woody plants. Some examples of these species include the Eastern Tent Caterpillar (Malacosoma americanum), Fall Webworm (Hyphantria cunea), Apple and Thorn Skeletonizer (Choreutis pariana), Many-dotted Appleworm (Balsa malana), Red-humped Appleworm (Schizura concinna), Wild Cherry Sphinx (Sphinx drupiferarum), Lesser Appleworm (Grapholita prunivora), Pale Apple Leafroller (Pseudexentera mali), and Apple Blotch Leafminer (Phyllonorycter crataegella). The Moth Table has a more complete list of these species. The larvae of two butterflies, the Tiger Swallowtail (Papilio glaucus) and Striped Hairstreak (Satyrium liparops), sometimes feed on the leaves. The fruits of Prairie Crab Apple, other crab apples, and the cultivated apple are sources of food to many mammals and birds. Mammals that eat these fruits include the Black Bear, Coyote, Gray Fox, Red Fox, Opossum, Raccoon, Striped Skunk, Spotted Skunk, Groundhog, Gray Squirrel, Fox Squirrel, and White-tailed Deer (Martin et al., 1951/1961; Barnes, 1999). By eating the fruits, these mammals spread the seeds of these woody plants to new locations (Myers et al., 2004). The White-tailed Deer also browses on the twigs and foliage, while the Cottontail Rabbit sometimes gnaws on the bark of saplings during the winter (Sotala & Kirkpatrick, 1973; Haugen, 1942).

Depending on the species, various birds feed on the buds, fruits, and/or seeds of the Prairie Crab Apple, other crab apples, and the cultivated apple. For example, the Ruffed Grouse, Purple Finch, and White-throated Sparrow eat the buds, while the Hairy Woodpecker, Starling, and Grackle peck at the fruits. The Bird Table has a more complete list of these species. Because these woody plants, including Prairie Crab Apple, are often densely branched, they provide good nesting habitat for the Yellow-breasted Chat, Orchard Oriole, Song Sparrow, and other birds. Woodpeckers and other insectivorous birds also benefit from the large variety of insects that these woody plants attract. Prairie Crab Apple, in particular, provides good cover for many mammals and other kinds of wildlife because of its tendency to form dense thickets from clonal offsets.

Photographic Location: Edge of a woodland along a roadside in Champaign County, Illinois.

Prairie Crab Apple (Malus ioensis) is one of three native crab apples (Malus spp.) in Illinois. A second native species, Wild Crab Apple (Malus coronaria), is very similar in overall appearance, except that its leaves, young shoots, calyces, ovaries, and pedicels are hairless. This latter species has a more eastern distribution than Prairie Crab Apple. These two native crab apples differ from many introduced crab apples from Eurasia by having leaves with shallow lobes and greenish yellow fruits that exceed " across. They are also more likely to have thorns along their branches than these non-native species. A third native species, Southern Crab Apple (Malus angustifolius), is smaller in size than the preceding native crab apples, and its leaves are more narrow in shape. In Illinois, this crab apple is found in the southern section of the state. The flowers of native crab apples are large, fragrant, and showy during the short period when they bloom during the spring. They are parent species of some crab apple cultivars that have been developed as ornamental plants for landscapes. For example, Bechtel's Crab Apple is a double-flowered cultivar that has Prairie Crab Apple as a parent. In the past, the fruit of Prairie Crab Apple was used to make apple jelly, cider, and vinegar.