American Pawpaw (Asimina triloba)

General Info

The North American Pawpaw (Asimina triloba) calls 26 states home and can be found throughout much of the eastern United States including the upland forest here on base (7).

It can be identified by its large somewhat oval-shaped leaves with smooth edges arranged alternately on the stems but can appear in some cases to be fanned out in a palm-like pattern. The trees have relatively smooth bark that is brown in color and often sports small gray patches. Pawpaws can reach heights of 30 feet (4).

The large green-yellow fruits produced by the pawpaw are the largest eatable fruit in North America and typically ripen from late August to early October. However, if you want a taste you’ll have to keep an eye out as many fruits get eaten by animals long before they become fully ripe and can be harvested by humans. The taste of the pawpaw fruit is described as banana-like or a mix of banana, mango, and pineapple with a custardy consistency (6).

The English name for the pawpaw plant is thought to come from confusion when word of the plant’s existence was first relayed to Europe by Spanish explorers. It’s thought that the Spanish called the plant papaya confusing it for the similar-looking though unrelated plant (1).

Natural History

Pawpaws are exclusively found in the oak-hickory upland forests on base. These trees have evolved to be adapted to the lower light conditions of the forest understory. Their large leaves provide a large surface area help to maximize photosynthesis and produce food for themselves in these lowlight conditions of the forest understory (10).

Pawpaws are different from a lot of the other tree species found in Leavenworth’s forests because they grow in patches. These patches are formed when specialized underground stems called rhizomes which branch outward and periodically form above-ground stems. Since they are so connected to one another by rhizomes, a single patch the trees may actually be one organism that is connected by rhizomes and genetically the same. These patches may live for decades and in some cases, centuries depending on various factors (5).

Pawpaws provide a phenomenal service to many organisms that call the forests of Leavenworth home. One of the species that would not exist on post if there were no pawpaws is the Zebra Swallowtail Butterfly (Eurytides marcellus). These appropriately named black and white butterflies use the pawpaw as a host plant for their eggs. Once the eggs hatch the caterpillars eat young leaves of the pawpaw (3). This is particularly interesting as pawpaws produce natural toxins called annonaceous acetogenins that are displeasing to many organisms that may attempt to eat the leaves or stems of the pawpaw. However, the zebra swallowtail caterpillars are capable of eating these toxins and in turn, become somewhat toxic and unpalatable to any potential predators (8).

The fruit of the pawpaw is readily eaten by many animals in the forest and provides a great nutritional benefit, however, the seeds are often too large for many modern animals to consume. Therefore, the seeds can only be carried over short distances. The wide distribution of the pawpaw in the United States raises questions as to how they became so widespread if their seeds can only be carried short distances. It is thought that before humans dispersed pawpaws, prehistoric megafauna or large prehistoric animals ate, digested, and deposited the seeds of pawpaws.

Historical and Indigenous Uses

Indigenous info

Traditionally the pawpaw fruit has been consumed for generations where the plant is native. The bark from the pawpaw was used by the Cherokee to make ropes and strings some of which were used for fishing. Some Native American tribes used a powder made from ground-up seed to help protect against head lice (9).

Colonial info

The infamous explorers Lewis and Clark are noted to have visited a site on the Missouri River that would later become Fort Leavenworth on their westward journey. On their return trip game animals became hard to find and their expedition team of around 50 people had to ration food, but fortunately found sustenance in pawpaw fruits they found in floodplain areas along the Missouri (2).

Citations

[1] Brode, J. (2023, January 9). Way down yonder in the paw-paw patch. Smithsonian Gardens. https://gardens.si.edu/learn/blog/way-down-yonder-in-the-paw-paw-patch/

[2] Compton, Brian Douglas, "The ethnobotany of the pawpaw, Asimina triloba (L.) Dunal" (1986).Masters Theses. 745. http://thekeep.eiu.edu/theses/745

[3] Epps, M. L. (2020, April 21). Pawpaws and the zebra Swallowtail Butterfly. Virginia Native Plant Society. https://vnps.org/paw-paws-and-the-zebra-swallowtail-butterfly/

[4] HADDOCK, M. J. (2019). Trees, shrubs, and Woody Vines in Kansas. University Press of Kansas.

[5] Hosaka, N., Kachi, N., Kudoh, H., Stuefer, J. F., & Whigham, D. F. (2007). Patch structure and Ramet Demography of the Clonal Tree, Asimina triloba, under gap and closed-canopy. Plant Ecology, 197(2), 219–228. https://doi.org/10.1007/s11258-007-9372-z

[6] Huang, H., Layne, D. R., & Kubisiak, T. L. (2000). RAPD inheritance and diversity in pawpaw (Asimina triloba). Journal of the American Society for Horticultural Science, 125(4), 454–459. https://doi.org/10.21273/jashs.125.4.454

[7] Jones, S. C., & Layne , D. R. (n.d.). Pawpaw Description and Nutritional Information. Pawpaw Description and Nutritional Information | Kentucky State University. https://web.archive.org/web/20191230230839/https://kysu.edu/academics/cafsss/pawpaw/pawpaw-description-and-nutritional-information/

[8] Martin, J. M., Madigosky, S. R., Gu, Z., Zhou, D., Wu, J., & McLaughlin, J. L. (1998). Chemical defense in the zebra swallowtail butterfly, Eurytides Marcellus, involving annonaceous acetogenins. Journal of Natural Products, 62(1), 2–4. https://doi.org/10.1021/np980308s

[9] Sheu, S. (n.d.). Foods indigenous to the Western Hemisphere: PawPaw. American Indian Health and Diet Project. https://aihd.ku.edu/foods/Pawpaw.html#:~:text=The%20fruit%20has%20also%20been,to%20make%20liquors%20(Austin)

[10] Snyder, E. (2022, September 19). Native Pawpaw Tree. NC Cooperative Extension News. https://caldwell.ces.ncsu.edu/2017/09/native-pawpaw-tree/