A. triloba is a large shrub or small tree growing to a height of 35 ft (11 m), rarely as tall as 45 ft (14 m), with trunks 8–12 in (20–30 cm) or more in diameter.
The large leaves of pawpaw trees are clustered symmetrically at the ends of the branches, giving a distinctive imbricated appearance to the tree's foliage.

The leaves of the species are simple, alternate and spirally arranged, entire, deciduous, obovate-lanceolate, 10–12 in (25–30 cm) long, 4–5 in (10–13 cm) broad, and wedge-shaped at the base, with an acute apex and an entire margin, with the midrib and primary veins prominent.
The petioles are short and stout, with a prominent adaxial groove.
Stipules are lacking.
The expanding leaves are conduplicate, green, covered with rusty tomentum beneath, and hairy above; when fully grown they are smooth, dark green above, and paler beneath.
When bruised, the leaves have a disagreeable odor similar to a green bell pepper.
In autumn, the leaves are a rusty yellow, allowing pawpaw groves to be spotted from a long distance.

Pawpaw flowers are perfect, about 1–2 in (3–5 cm) across, rich red-purple or maroon when mature, with three sepals and six petals.
They are borne singly on stout, hairy, axillary peduncles.
The flowers are produced in early spring at the same time as or slightly before the new leaves appear, and have a faint fetid or yeasty smell.

The fruit of the pawpaw is a large, yellowish-green to brown berry, 2–6 in (5–15 cm) long and 1–3 in (3–8 cm) broad, weighing from 0.7–18 oz (20–510 g), containing several brown or black seeds ¹⁄₂–1 in (15–25 mm) in diameter embedded in the soft, edible fruit pulp.
The conspicuous fruits begin developing after the plants flower; they are initially green, maturing by September or October to yellow or brown.
When mature, the heavy fruits bend the weak branches down.

Other characteristics:
Calyx: Sepals three, valvate in bud, ovate, acuminate, pale green, downy
Corolla: Petals six, in two rows, imbricate in the bud; inner row acute, erect, nectariferous; outer row broadly ovate, reflexed at maturity; petals at first are green, then brown, and finally become dull purple or maroon and conspicuously veiny
Stamens: Indefinite, densely packed on the globular receptacle; filaments short; anthers extrorse, two-celled, opening longitudinally
Pollen: Shed as permanent tetrads
Pistils: Several, on the summit of the receptacle, projecting from the mass of stamens; ovary one-celled; stigma sessile; ovules many
Branchlets: Light brown, tinged with red, marked by shallow grooves
Winter buds: Small, of two kinds, the leaf buds pointed and closely appressed to the twigs, and the flower buds round, brown, and fuzzy
Bark: Light gray, sometimes blotched with lighter gray spots, sometimes covered with small excrescences, divided by shallow fissures; inner bark tough, fibrous; bark with a very disagreeable odor when bruised
Wood: Pale, greenish yellow, sapwood lighter; light, soft, coarse-grained and spongy with a specific gravity of  0.3969 and a density of 24.74 pounds per cubic foot (396.3 kg/m³)
Longevity of fruit production: Undetermined
A. triloba is a large shrub or small tree growing to a height of 35 ft (11 m), rarely as tall as 45 ft (14 m), with trunks 8–12 in (20–30 cm) or more in diameter. The large leaves of pawpaw trees are clustered symmetrically at the ends of the branches, giving a distinctive imbricated appearance to the tree's foliage.
The leaves of the species are simple, alternate and spirally arranged, entire, deciduous, obovate-lanceolate, 10–12 in (25–30 cm) long, 4–5 in (10–13 cm) broad, and wedge-shaped at the base, with an acute apex and an entire margin, with the midrib and primary veins prominent. The petioles are short and stout, with a prominent adaxial groove. Stipules are lacking. The expanding leaves are conduplicate, green, covered with rusty tomentum beneath, and hairy above; when fully grown they are smooth, dark green above, and paler beneath. When bruised, the leaves have a disagreeable odor similar to a green bell pepper. In autumn, the leaves are a rusty yellow, allowing pawpaw groves to be spotted from a long distance.
Pawpaw flowers are perfect, about 1–2 in (3–5 cm) across, rich red-purple or maroon when mature, with three sepals and six petals. They are borne singly on stout, hairy, axillary peduncles. The flowers are produced in early spring at the same time as or slightly before the new leaves appear, and have a faint fetid or yeasty smell.
The fruit of the pawpaw is a large, yellowish-green to brown berry, 2–6 in (5–15 cm) long and 1–3 in (3–8 cm) broad, weighing from 0.7–18 oz (20–510 g), containing several brown or black seeds ¹⁄₂–1 in (15–25 mm) in diameter embedded in the soft, edible fruit pulp. The conspicuous fruits begin developing after the plants flower; they are initially green, maturing by September or October to yellow or brown. When mature, the heavy fruits bend the weak branches down.
Other characteristics:
Calyx: Sepals three, valvate in bud, ovate, acuminate, pale green, downy
Corolla: Petals six, in two rows, imbricate in the bud; inner row acute, erect, nectariferous; outer row broadly ovate, reflexed at maturity; petals at first are green, then brown, and finally become dull purple or maroon and conspicuously veiny
Stamens: Indefinite, densely packed on the globular receptacle; filaments short; anthers extrorse, two-celled, opening longitudinally
Pollen: Shed as permanent tetrads
Pistils: Several, on the summit of the receptacle, projecting from the mass of stamens; ovary one-celled; stigma sessile; ovules many
Branchlets: Light brown, tinged with red, marked by shallow grooves
Winter buds: Small, of two kinds, the leaf buds pointed and closely appressed to the twigs, and the flower buds round, brown, and fuzzy
Bark: Light gray, sometimes blotched with lighter gray spots, sometimes covered with small excrescences, divided by shallow fissures; inner bark tough, fibrous; bark with a very disagreeable odor when bruised
Wood: Pale, greenish yellow, sapwood lighter; light, soft, coarse-grained and spongy with a specific gravity of  0.3969 and a density of 24.74 pounds per cubic foot (396.3 kg/m³)
Longevity of fruit production: Undetermined
Asimina triloba