Know Your Natives – Pawpaw

Pawpaw (Asimina triloba) of the Custard Apple (Annonaceae) family is a small deciduous understory tree with edible fruit. It is widespread in the deciduous forests of the eastern U.S., from eastern Texas and southeastern Nebraska, east across southern Michigan to the Atlantic Coast from Pennsylvania to northern Florida. In Arkansas it occurs statewide. The genus name is based on the Native American name “assimin.” The specific epithet refers to the number of petals and sepals. The common name “pawpaw” was first used by the English in the 16th century for papaya (Carica papaya) and later used by early American settlers for this species. Along with various spellings of pawpaw, other common names include Arkansas banana, wild banana, custard apple, and banango. Habitats include deep, mesic, sandy to clayey soils of rich, shaded bottomlands, floodplains, ravines, and slopes. Pawpaws have deep taproots with shallow runners that produce nearby clonal sprouts. Trees have slender and branch-free lower trunks. Mature trees are typically from 15 to 20 feet tall, but may reach 40 feet.

Leaves and branches are alternate, in two opposing rows, however this arrangement becomes less noticeable as some branches and twigs become dominant while others die away. Short reddish pubescence on new branches is lost as they age and become glabrous. New bark is yellowish green before becoming reddish brown to gray during the first year. Bark of mature trunks is thin, gray to gray-brown, with lighter splotches, corky lenticels (air pores), and minimal fissuring.

Photo 1: Trunks are fairly smooth and gray to gray-brown, with corky lenticels and minimal fissuring. Photo – March 16.

In late March into mid-April, single flowers emerge from rounded lateral buds along year-old branches. In mid-winter, the dark fuzzy flower buds are knobby. With anthesis approaching, they become yellowish green before changing to deep reddish brown to purple. First flowers tend to open before leaves appear, but then leaf growth and flower progression continues simultaneously for about a month.

Photo 2: Branch and twig growth is alternate in opposing rows. Flowers occur on twigs with the outermost buds blooming first. Dark leaf in upper corner is Ozark Witch Hazel. Photo – March 26.

Flowers, about 1½ inches across, are pendulous, with three sepals, and a veiny corolla of three larger outer petals and three smaller inner petals, both whorls a striking maroon to reddish brown. Pedicels and sepals are covered by a dense reddish brown pubescence. Flowers have a somewhat fetid scent which attracts pollinating flies.

Photo 3: When multiple flowers occur on a twig, the more distal flower(s) bloom first. Flowers change from yellowish green to reddish purple. In spring, pedicels and sepals have dense reddish brown pubescence. Photo – April 4.
Photo 4: As flowers progress from bloom to fruit, twigs continue their terminal leafy growth. Scars of previous year’s leaves each subtend a single flower (which may bear more than a single fruit). Photo – April 10.

Flowers have an elongate receptacle bearing a dense mass of numerous stamens surrounding a cluster of 3-6 separate pistils. The stamens have stubby filaments topped with tightly packed, pale yellow anthers that en mass create a brain-like surface. Pistils consist of elongate ovaries, with short styles and rounded yellowish stigmas. After anthesis, stamens disintegrate as the receptacle shrinks to eventually form a “ring-collar” at the base of the fruit.

Photo 5: Three flowers with larger outer petals and one smaller inner petal removed. The large, yellowish, brain-like structure in center of two flowers at left is the mass of tightly packed stamens, from which the stigmas protrude. Flowers maturing from left to right.
Photo 6: Flowers have three to six pistils with nearly sessile stigmas. Interior of petals is shown except the two petals on right.

Leaves emerge after flowers have begun to bloom. Short, reddish pubescence is lost with leaf maturity. Simple oblanceolate leaves grow to about 1 foot long and 3½ inches wide with ⅜-inch petioles. Margins are entire. Crushed leaves have a strong, distinctive scent, like green peppers––a useful field character.


Photo 7: Purplish, hairy, elongate terminal buds are naked, i.e., they lack bud scales and consist only of embryonic leaves. Rounded lateral buds produce next year’s flowers. Photo – August 5.
Photo 8: Alternate leaves in two opposing rows, are angled toward the twig tip. Principal leaves are oblanceolate. Leaves show upper (adaxial) surface except leaf on right showing lower (abaxial) surface. Photo – August 5.

Pollinated flowers may produce one or a cluster of several rounded to oblong fruits (large berries) 1-4 inches long. Fruits develop from bluish green to yellowish as they ripen and may weigh a half-pound or more. An isolated tree may produce fruit, but cross-pollination increases fruit production. The greenish pulp becomes white to yellow, soft, sweet, and delicious as the fruit matures. Fruits contain to about 10 dark brown, inch-long, smooth and shiny seeds in two rows. Peduncles, at fruit maturity, may be an inch or more long.

Photo 9: A single flower may produce one or several fruits. When ripe, fruits become less firm and detach easily from their elongated peduncles. Photo – August 14.
Photo 10: Ripened fruit quickly softens. This fruit, with a light yellowish green skin, is 3 inches long. Largest of seeds shown at right (from a different fruit) is almost an inch long. Photo – August 17.

Pawpaws, with their large leaves, striking flowers, and delicious fruits, merit a special place in gardens and natural areas. They are easy to grow in partially sunny areas as well as, once established and with adequate moisture, sunny areas. Trees in sunnier areas will be less leggy and bear more flowers and fruit. The fruits have a banana-mango (?) flavor appreciated by many people. If a colony is not desired, clonal sprouts need to be removed annually. In early winter, those sprouts can be successfully transplanted with appropriate care (shading and watering). Leaves are not eaten by deer, but fruits are a favorite of deer, box turtles, raccoons, and other small mammals. Pawpaws are host plants for the Zebra Swallowtail (Protographium marcellus), Pawpaw Sphinx Moth (Dolba hyloeus), and the Asimina Webworm Moth* (Omphalocera munroei).

Photo 11: In a sunny native plant garden, if clonal sprouts are removed annually, a leafy specimen tree can develop. This 12-year old tree produces numerous flowers and a few fruits, even without a second close tree for cross-pollination. Photo – June 27.

Dwarf pawpaw (Asimina parviflora), a species of conservation concern in Arkansas, is the only other species of the genus in Arkansas (Miller and Union Counties). Dwarf pawpaws are more shrub-like with significantly smaller but similar leaves, flowers, and fruit.

* Caterpillars of Asimina Webworm Moth bind terminal leaves into ugly wads of dead leaves. As long as the terminal buds are not damaged, branches continue normal growth the next spring.

Article and photographs by ANPS member Sid Vogelpohl

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