Asimina triloba, the American papaw, pawpaw, paw paw, or paw-paw, among many regional names, is a species of small deciduous tree. It has large leaves and produces a large, yellowish-green to brown fruit.
The species is native to eastern North America, in a more temperate range than its tropical relatives. It is a Clonal colony-forming (clonal) understory tree of hardwood forests, being found in well-drained, deep, fertile bottomland and also hilly upland habitat.
Although much of the plant contains the neurotoxin annonacin, the ripe fruits are edible. They are sweet, with a custard-like texture and a flavor somewhat similar to banana or pineapple. They are commonly eaten raw, but are also used to make ice cream and baked desserts.
The leaf of the species are simple, alternate and spirally arranged, entire, deciduous, lanceolate, long, 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 are Perfect flower and protogynous, about 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 to attract pollinators.
The fruit of the pawpaw is a large, yellowish-green to brown berry, long and broad, weighing from , containing several brown or black 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 green, yellowish green, or brown. When mature, the heavy fruits bend the weak branches down. Full ripening often happens only after the fruit falls naturally, thus signifying a seed dispersal strategy aimed at ground-based, rather than arboreal, mammals.
Other characteristics:
Within its natural habitat, pawpaw grows in slightly acidic (pH 5.5 – 7.0), well-drained soils. These trees typically establish as part of the understory in Eastern Temperate Forest (Carolinian Forest) region. Pawpaws are also found along , stream banks, and shaded, nutrient-rich bottomlands, but they prefer gently elevated slopes because it has a deep-reaching taproot. While pawpaws are shade tolerant, maximum fruit yields occur under full sun conditions with some wind protection. However, germinating seedlings are extremely sensitive to full sun and require partial shading during their first one or two years.
One southern U.S. species, Asimina parviflora, does overlap in range with pawpaw. This species is smaller than pawpaw in both its flower and its woody growth. A. parviflora is more shrublike, rarely growing even a third as tall as pawpaw. Genomically verified hybrids of A. triloba and A. parviflora have been classified as Asimina piedmontana.
The floral scent of Asimina triloba has been described as "yeasty", which is one of several features that signify a "beetle pollination syndrome". Other floral features of pawpaw indicative of beetle pollination include petals that curve over the downward-pointing flower center, along with food-rich fleshy bases of the inner whorl of petals. A "pollination chamber" is thereby created at a depth that only small beetles can access during the initial female-receptive stage of floral bloom. As with other well-studied species of Annonaceae, the delay in the shift from female to male floral stage offers beetles a secure, and possibly thermogenic, residence in which not only to feed but also to mate. Receptive stigmas at their arrival, followed by pollen-shedding stamens during pollinator departure, are regarded as an early form of mutualism evolved between plants and insects that is still dominant in the most ancient lineages of flowering plants, including the Magnoliids (of which Annonaceae is the most species-rich taxonomic family).
Beetles are the dominant form of pollinator ascribed for genera and species within the Annonaceae family. However, two species of genus Asimina ( Asimina triloba and Asimina parviflora) bear a floral character that has given rise to an alternative hypothesis that carrion or dung flies are their effective pollinators. That floral characteristic is the dark maroon color of the petals. Hence, while no scholarly papers have documented carrion or dung flies as effective pollinators in field observations, the strength of this hypothesis has led to placement of carrion during the bloom time in pawpaw orchards by some horticultural growers.
Professional papers on genus Asimina and its species have warned of the difficulties in discerning whether insects observed on or collected from flowers are effective pollinators or merely casual and thus opportunistic visitors.
A citizen science project in southern Michigan utilized natural history forms of observation, along with video and photo documentation, during a "pawpaw pollinator watch" in May 2021. Two species of tiny sap beetle were reported as the most abundant and the most consistently present insect types at depth within the flowers, and thus as the most likely effective pollinators. The two species are Glischrochilus quadrisignatus and Stelidota geminata. Both are in the taxonomic family sap beetle. Nitidulid beetles are described by Clemson University as likely "night flying" pollinators of pawpaw. Larvae and adult beetle stages of Glischrochilus quadrisignatus were also documented by the citizen project on the ground-level side of rotting fruit in a pawpaw orchard in Michigan following the fruit harvest.
The megafaunal dispersal syndrome is a common feature of some plants native to the Western Hemisphere, where a large proportion of megafauna went extinct near the end of the glacial episodes. Such fruits are now regarded as evolutionary anachronisms. Their anatomical features, such as seeds too big for today's fruit eaters to swallow and then defecate, means they are no longer well adapted for current ecological conditions.
Another indicator of dispersal adaptation for megafauna is that pawpaw fruit (wild types and most cultivars) tend to remain green or become blotched with brown when at peak ripeness. Mammals (other than primates) rely on olfactory system rather than visual clues for discerning ripe fruit, so fruit color is no signal of ripeness for large mammals. An advantage of maintaining green fruit skin throughout the ripening process is that photosynthesis can continue during this time.
Following the extinction of much of the ice age megafauna, bears would have continued dispersing pawpaw seeds in their dung. Hand carrying of fruit and seeds by humans expanding from Asia into North America would have extended the range of long-distance seed dispersal. Humans intentionally continue this role today via horticulture plantings, along with wild plantings as far north as Massachusetts, Pennsylvania, and Michigan. Small , including raccoons, gray foxes, opossums, and squirrels, assist in local movements of seeds. Asimina triloba , Fire Effects Information System, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory
Larvae of the zebra swallowtail ( Eurytides marcellus), a Lepidoptera, feed exclusively on young leaves of A. triloba and various other pawpaw ( Asimina) species, but do not occur in great numbers on the plants. Chemicals consumed by the caterpillars confer protection throughout the butterflies' lives, as trace amounts of acetogenins remain present, making them unpalatable to birds and other predators. A partially citizen-led project in Pittsburgh, Pennsylvania is working on restoring pawpaw for the purpose of encouraging return of the zebra swallowtail as well as the general restoration of riparian areas.
In June 2024 a zebra swallowtail was documented laying eggs on a backyard pawpaw plant in Pittsburgh. This was the first time that this butterfly species was seen there since industrialization and river slope destruction had decimated its plant host. A local news editorial wrote, "The return of the zebra swallowtail, after 87 years, is a huge success for naturalists, conservationists and native tree lovers.... Organizations like Grow Pittsburgh, Tree Pittsburgh, the Pittsburgh Parks Conservancy and dedicated chat groups for Pittsburgh conservationists made the zebra swallowtail butterfly’s restoration possible."
Other insects that have evolved the ability to consume pawpaws include Talponia plummeriana, the pawpaw peduncle borer, whose larvae can be found in flowers, and Omphalocera munroei, the asimina webworm, whose larvae mostly feed upon leaves. Drosophila suzukii, the spotted wing drosophila, and Zaprionus indianus, the African fig fly, have been recorded developing within pawpaw fruit collected in Connecticut, United States, marking the first known use of a member of the Annonaceae family by D. suzukii and an expansion of the known host range of Z. indianus.
Patch-forming clonal growth is achieved by way of shallow, horizontally spreading stems (rhizomes). By retaining these interconnections, photosynthates can be shared among the stems (ramets). Stems that access sunlight can grow as tall as 30 feet and will bear the most fruit. Stems that develop under canopy shade tend to curve and bend in quest of sunlight patches, with a greater density of small stems than where the tallest stems have captured the canopy positions.
Pawpaws are not the first to colonize a disturbed site, but because they are capable of growing in deep shade, they can establish from seed beneath mature deciduous trees and then spread into a subcanopy patch. They may even become dominant through time by depriving native canopy trees from re-establishing via seed in a treefall gap, owing to the dense shade within a pawpaw patch. Under such circumstances, the pawpaw subcanopy becomes the forest canopy, albeit at a height half as high as the usual canopy of native trees. Accessing full sunlight, the patch is then capable of producing more fruit.
Upslope expansion has been attributed to a lessening of human-set fires within forested habitats of the eastern United States. Unlike common canopy trees such as Quercus and Pinus, pawpaw has no resistance against ground fires. So a reduction in fires has enabled pawpaw, as well as other shade-adapted native trees (including American beech and striped maple), to become more common. As well, because toxins in the bark, twigs, and leaves of pawpaw repel herbivory, forests browsed by overpopulated deer offer pawpaw even more competitive advantages.
Pawpaw exhibits a high tolerance for intense shading, even compared with other shade-adapted species such as striped maple. Pawpaw leaves cast very heavy shade, and this chokes out seedlings and saplings of most canopy species (though not native spring herbs that benefit from the late-leafing habit of pawpaw). This helps pawpaw outcompete rival species and is a contributor to its increased abundance in forests across its range.
In areas in which deer populations are dense, pawpaws appear to be becoming more abundant locally, since the deer avoid them but consume seedlings of most other .
As for native disease, the pawpaw fares very well. There are no known disease agents (including insects) that are especially damaging. Consequently, planting of pawpaw for landscaping or fruit production requires little to no attention to disease management.
As a native species, pawpaw can be planted on river slopes for erosion control, as introduced species formerly used in the eastern United States for this purpose (such as non-native bamboo species and Lonicera maackii) are now discouraged or prohibited because of their invasive species. In the two photos at right, pawpaw was chosen for post-industrial forest restoration as the ideal native competitor against the now-dominant Amur honeysuckle and increasing numbers of non-native privet in southern Michigan.
In the eastern United States, where large predation are almost entirely lacking, pawpaw is one of the few native subcanopy trees whose bark and leaves are too poisonous for deer to browse. It is therefore a viable species for forest understory restoration in areas where fragmented landscapes, dwellings, and parks status preclude hunting as a population control. The nonexistent commercial demand of pawpaw timber also protects trees used for ecological reasons from potential future harvest.
Pawpaws have not been cultivated for their fruits on the scale of or , primarily because pawpaw fruits ripen to the point of fermentation soon after they are picked, and only frozen fruit stores or ships well. Other methods of preservation include Dried fruit, production of jams or jellies, and pressure canning (using the numerical values for bananas). Methods of separating seeds from the pulp are still in the experimental phase. Mechanical methods are most efficient, but any splitting or injury of seeds can contaminate the remaining pulp with seed poisons.
Commercial pawpaw production tends to be less intensive than other fruit trees. Pawpaw requires very little pesticide/herbicide, even when planted as a monoculture. Because of its long taproot, pawpaw grows well even in drier upland plantings. Cultivation of pawpaws for fruit production has attracted interest, particularly among organic farming, as a fruit with few to no pests that can successfully be grown in its native environment without . The commercial cultivation and harvesting of pawpaws is strongest in southeastern Ohio and also being explored in Kentucky and Maryland, as well as various areas outside the species' native range, including California, the Pacific Northwest, and Massachusetts. In New York state, due to climate change's impact on traditional fruit crops, such as apples and peaches, farmers are looking to pawpaw as a new commercial crop.
Changing perspectives of the general population towards a healthier and environmentally conscious diet has led to increased interest in the pawpaw as food in recent years. Using pawpaw puree as a substitute for other sweeteners and creamers adds micronutrients such as iron and manganese while typically reducing the total sugar content as well as glycemic index of most recipes. If done correctly this will not negatively impact the quality of baked goods or desserts. In a study conducted using pawpaw puree in muffins, the pawpaw muffins were preferred in the blind taste test over the control (sugar) and other sweeteners (apple puree). Frozen pawpaw pulp is used in ice cream and smoothies, and some craft brewers use the fruit in sour beers and meads. The pawpaw is also used for landscaping due to its distinctive growth habit, the appeal of its fresh fruit, and its relatively low maintenance needs once established.
As of 2024, global weather changes have led to the loss of many American apple and peach crops due to cold weather, making Pawpaw farming an increasingly favorable alternative because of its resilience to weather fluctuations.
Given the 6 to 7 year maturity time and relatively poor success rates for dispersal and germination, it often requires 7 to 10 years for a sapling-to-sapling life cycle to occur for a given individual.
Propagation using cuttings has generally not been successful.
Desirable are propagated by chip budding or whip grafting onto a root stock. Pawpaw seeds do not grow "true to type" — each individual seed in a fruit is genetically different from the others and from its parent tree. Purchased cultivars do not produce seeds true to type, either, which is why cultivars are all grafted trees. Root sucker seedlings, however, are all genetically identical to their host.
Commercial nurseries usually ship grafted cultivars in containers. Other nurseries, such as the Kentucky Division of Forestry, ship bareroot seedlings for reforestation projects and area homeowners.
Harvesting small stems within a wild pawpaw patch is usually unsuccessful because most are clones of (and still connected to) adjacent stems and therefore lack fully developed roots.
Kentucky State University (KSU) has a pawpaw research program Kentucky State University | Pawpaw which seeks to develop methods and varieties to increase the viability of the pawpaw to be grown as a commercial fruit crop.
The named varieties producing large fruit and performing well in Kentucky per research trials are 'NC-1', 'Overleese', 'Potomac', 'Shenandoah', 'Sunflower', 'Susquehanna', 'Wabash', KSU-'Atwood', KSU-'Benson', and KSU-'Chappell'.
While consumption of annonacin-containing plant products has been linked to atypical parkinsonism, the populations most at risk are those who regularly consume large amounts of fruit products from the Annonaceae family. There is currently no established oral LD50 for annonacin in humans or animal models.
The earliest documented mention of pawpaws is in the 1541 report of the Spain de Soto expedition, who found Native Americans east of the Mississippi River cultivating what some have identified as the pawpaw. The tree's scientific name ( Asimina triloba) comes from the Powhatan word Assimina, which a Jamestown settler transcribed in 1612 as "wheat plum". The Lewis and Clark Expedition consumed pawpaws during their travels. Thomas Jefferson planted it at Monticello, his plantation in Virginia.
Historically, the pawpaw was a commonly-eaten fruit throughout its native range. With the advent of motor travel and refrigeration, it has been used less commonly to the point of obscurity in favor of other commercial fruits. Despite its very short shelf life, vulnerability to bruising, and inability to fully ripen if harvested early, pawpaw has developed a specialty market appeal in some regions of its native range, including southern Ontario.
As described by horticulture Barbara Damrosch, the fruit of the pawpaw "looks a bit like mango, but with pale yellow, custardy, spoonable flesh and black, easy-to-remove seeds." Wild-collected pawpaw fruits ripen in late August to mid-September through most of their range, but a month later near their northward limit. They have long been a favorite treat throughout the tree's extensive native range in eastern North America, and on occasion are sold locally at farmers' markets.
Pawpaw fruits have a sweet, custard-like flavor somewhat similar to banana, mango, and cantaloupe, varying significantly by source or cultivar, with more protein than most fruits. Nineteenth-century American agronomist E. Lewis Sturtevant described pawpaws as "a natural custard, too luscious for the relish of most people." Ohio botanist William B. Werthner wrote, "The fruit ... has a tangy wild-wood flavor peculiarly its own. It is sweet, yet rather cloying to the taste and a wee bit puckery – only a boy can eat more than one at a time."
Fresh fruits of the pawpaw are commonly eaten raw, either chilled or at room temperature. However, they can be shelf life only 2–3 days at room temperature, or about a week if refrigerated. This short shelf-life, difficulty shipping whole, and the importance of removing the inedible skin and toxic seeds prior to processing are a primary barrier to the success of pawpaw as a commercial fruit. The easily bruised pawpaw fruits do not ship well unless frozen. Where pawpaws grow, the fruit pulp is also used locally in baked dessert recipes, with pawpaw substituted with volumetric equivalency in many banana-based recipes. The sweet and creamy fruit is commonly mixed into ice cream or blended into and other breads.
Pawpaw logs have been used for in Arkansas. The hard, brown, shiny lima-bean-sized seeds were sometimes carried as Touch piece in Ohio. Due to the presence of acetogenins, the leaves, twigs, and bark of pawpaw trees can be used to make an organic insecticide.
Yet A. triloba has had numerous local common names, many of which compare it to a banana rather than to Carica papaya. These include wild banana, prairie banana, Indiana banana, Hoosier banana, West Virginia banana, Kansas banana, Kentucky banana, Michigan banana, Missouri banana, Appalachian banana, Ozarks banana, Indian banana, banango, and the poor man's banana, as well as American custard apple, asimoya, Quaker delight, and hillbilly mango.
Several tribes of Native Americans have terms for the pawpaw such as riwahárikstikuc (Pawnee language), tózhaⁿ hu (Kansa language), and umbi (Choctaw language).
He notes that "picking up pawpaws" refers to gathering the ripe, fallen fruit from beneath the trees, and that the "pocket" in the song is that of an apron or similar tie-on pocket, not a modern trousers or Jeans pocket, into which pawpaws would hardly fit. A "pawpaw patch" refers to the plant's characteristic patch-forming clonal growth habit.
Taxonomy
Etymology
Distribution and habitat
Ecology
Hybridization with other Asimina species
Pollination
Seed dispersal
Interactions with animals
Patch-forming clonal growth
Shifting dynamics
Conservation
Disease
Habitat restoration
Cultivation
Propagation
Cultivars
Toxicity
Uses
Edible fruit
Nutrition
Other uses
Phytochemicals
Research
In culture
Common names
The original "papaw" ... is Carica papaya. By 1598, English-speaking people in the Caribbean were calling these plants "pawpaws" or "papaws" ... yet the temperate Americas, they found another tree with a similarly aromatic, sweet fruit. It reminded them of the "papaya", which had already become "papaw", so that is what they called these different plants ... By 1760, the names "papaw" and "pawpaw" were being applied to A. triloba.
Old song
Place names
Art
Other
Further reading
External links
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