Red Ash
Fraxinus pennsylvanica pennsylvanica
Olive family (Oleaceae)

Description: This tree is 50-100' at maturity (rarely taller), forming a single trunk about 2-3' across and an ovoid crown with ascending to spreading branches. The trunk is normally straight and upright, forming a thick layer of gray bark with interlaced ridges that form narrowly diamond-shaped cavities. The bark of larger branches is gray and somewhat scaly, while young twigs are gray to reddish brown and smooth. New leafy shoots are green and hairy. Opposite compound leaves occur along the shoots and twigs. The scars from detached leaves along the twigs have a half-circle shape (or slightly less than a half-circle). These leaves are odd-pinnate with 5-9 leaflets (usually, there are 7), spanning about 6-14" long and about one-half as much across. The central stalk (rachis) and petiole of each leaf are light green and hairy. Individual leaflets are 2-5" long and -2" across; they are elliptic or lanceolate in shape and smooth to slightly serrated along their margins. At the base of each leaflet there is a short petiolule that is light green and hairy. The upper surface of the leaflets is medium to dark green and glabrous, while the lower surface is light green and covered with short woolly hairs. Usually the hairs on young shoots and leaves are brown, although sometimes they are white. Each leaflet has 8-12 pairs of lateral veins that diverge from a central vein.


Because Red Ash is dioecious, some trees have all male flowers, while other trees have all female flowers. These flowers typically bloom during mid-spring for about 2 weeks before the development of the leaves; they are cross-pollinated by the wind. The male flowers develop in tight clusters along 2nd-year twigs. Individual male flowers are less than 1/8" (3 mm.) across, consisting of a tiny tubular calyx and a pair of stamens (there are no petals). Initially, the male flowers are yellowish green to greenish purple, becoming gray-brown after the stamens release their pollen. The female flowers develop in small panicles along 2nd-year twigs. Individual female flowers consist of a tiny tubular calyx and a pistil with a single style. After the blooming period, the male flowers wither away, while fertile female flowers are replaced by drooping panicles of samaras (winged seeds). Individual samaras are linear-oblanceolate, consisting of a small ellipsoid body containing a single seed and an elongated membranous wing that is rounded or slightly notched at its tip. The membranous wing extends along both sides of the body to about one-half of the latter's length. As they ripen, the samaras change from light green to yellow, and from yellow to tan. They are dispersed by wind or water during the fall or winter. The deciduous leaves usually turn yellow during the fall. The woody root system is widely spreading and relatively shallow. This tree can resprout from its trunk after being damaged, otherwise it reproduces by reseeding itself.

Cultivation: This tree prefers full sun to light shade, moist conditions, and soil containing clay-loam or silt-loam. Occasional flooding is tolerated. Growth and development are moderately fast for a tree. Red Ash typically lives 50-100 years, but sometimes as long as 200 years. The trunk and branches are frequently adorned with lichens and moss.

Range & Habitat: The native Red Ash is occasional to locally common throughout Illinois (see Distribution Map). Habitats include floodplain woodlands, mesic woodlands, riverbanks, swamps, and abandoned fields. Such deciduous trees as Silver Maple, Red Maple, Shellbark (Kingnut) Hickory, American Sycamore, and Eastern Cottonwood are common associates of Red Ash. It is occasionally cultivated as a landscape tree.

Faunal Associations: Many insects feed on the foliage or bore through the wood of Red Ash. These species include the caterpillars of the butterfly Papilio glaucus (Tiger Swallowtail), the caterpillars of many moths (see Moth Table), and the caterpillar-like larvae of Tomostethus multicinctus (Brown-Headed Ash Sawfly) and Tethida barda (Black-Headed Ash Sawfly). In the Midwest, one of the biggest threats to the survival of Red Ash and other Fraxinus spp. is a beetle that was introduced accidentally from abroad, viz. Agrilus planipennis (Emerald Ash Borer). Its larvae bore through the wood and often kill native Ash trees. Other insect feeders include Tropidosteptes amoenus (Ash Plant Bug), the flea beetle Trichaltica scabricula, larvae of the wood-boring beetles Tylonotus bimaculatus (Ash & Privet Borer) and Neoclytus acuminatus acuminatus (Red-Headed Ash Borer), Prociphilus americanus (Conifer Root Aphid) and Prociphilus fraxinifolii (Woolly Ash Aphid), Lepidosaphes ulmi (Oystershell Scale), and larvae of the gall fly Dasineura fraxinifolia (see the Insect Table for a more complete listing of these species).


The seeds of Red Ash are eaten by such birds as the Wood Duck, Wild Turkey, Bobwhite, Cardinal, and Pine Grosbeak. The seeds are also eaten by the Fox Squirrel, Red Squirrel, and White-Footed Mouse. The foliage and twigs of Red Ash are palatable to several hoofed herbivorous mammals: this includes deer, cattle, horses, and sheep. Rabbits eat the foliage of young saplings, while the beaver uses the wood as a food source. American Bison are attracted to the rough bark of mature trees, using their trunks for rubbing and horning activities. Red Ash provides cover, habitat, and roosting sites for the Eastern Screech Owl, Cooper's Hawk, Wild Turkey, Ruffed Grouse, Common Grackle, and other birds.

Photographic Location: The photographs were taken at Crystal Lake Park in Urbana, Illinois.


Comments: Red Ash is the typical variety of this tree. Another variety, Green Ash (Fraxinus pennsylvanica lanceolata), is the same as Red Ash except it has hairless young shoots, hairless petioles, hairless leaf stalks, and hairless leaflet undersides. The leaflets of Green Ash may be slightly more narrow than those of Red Ash on average. Some specimens of Fraxinus pennsylvanica display characteristics that are intermediate between Red Ash and Green Ash, making them difficult to classify. In Illinois, these two varieties are about equally common and they prefer similar habitats. However, Green Ash appears to be cultivated more often as a landscape tree than Red Ash. Some authorities treat these two varieties as distinct species (e.g., Mohlenbrock), while other authorities don't recognize them at even the varietal level (e.g., Karteze). As a group, different Ash tree species (Fraxinus spp.) are fairly difficult to distinguish from each other, although Red Ash is more hairy than most of them.

Return