01/04/2021

Paw Paw

The Ohio Chapter ISA continued efforts are to advance responsible tree care practices through research, technology, and education while promoting the benefits of trees. This month Tree-Of-The-Month is commonly known as the Paw Paw, Pawpaw, paw, or Paw-Paw, or the Latin name of Asimina triloba. The Paw Paw has leaves and branches that deer avoid browsing and fruit loved by all. The Paw Paw is a fascinating native tree. Deer find Pawpaw foliage unpalatable and, therefore, make the  Paw Paw tree easy to grow.

The Paw Paw is the only local member of a large, mainly-tropical plant family (Annonaceae). The Paw Paw tree is indigenous to 26 states in the United States, growing wild from the Gulf Coast up to the Great Lakes region. The plant family Annonaceae are woody trees, shrubs, and vines comprising approximately  130 genera, and 2,300 species are mostly found in tropical areas of the world. Similarly, there is a dwarf species known as Asimina parivflora, commonly known as the "Dwarf Paw Paw" or the "possum-simmon." Asimina. tetramera, commonly known as 'opossum pawpaw,' is a rare and endangered species from southern Florida. Other similar species include Asimina incarna,  Asimina longifolia, Asimina obovata, Asimina pygmaea, Asimina reticulata, and Asimina X nashii.  

The Paw Paw (Asimina triloba) is a perennial tree or shrub that grows from 10-40 feet tall and 10 to 15 feet wide. The Paw Paw has drooping, pear-shaped leaves that are alternate, from 10 to 30 cm long, with smooth margins and pointed tips. The Paw Paw leaves are coated with fine whitish hairs on the upper surface with rusty colored hairs on the under-side. The leaves of the Paw Paw are aromatic, with a smell reminiscent of bell pepper. The inconspicuous but attractive flowers of the Paw Paw(4 to 5cm in diameter) with three sepals are green upon opening and turn to dark purple or maroon. From 1 to 4 flowers grow in the leaf axils before leafing, usually in April or May. The six velvety petals of the Paw Paw (2cm-2.5cm long) are stiff and curl slightly backward. The Paw Paw fruit are yellowish-green to brown, cylindrical, mango-shaped fruits are 7-16 cm long and grow solitarily or 2 to 4 together. The large fruits of the Paw Paw that are 5 to 16 ounces will often ripen between August and October. Fruits have a thin skin containing a yellow custard-like pulp said to taste like mango and papaya. Some varieties include a whitish-green pulp that is less flavorful. Fruits have several flat 2 cm long seeds. The deciduous leaves turn bright yellow before dropping in the fall.

The Paw Paw produces the largest edible fruit native to North America and is an odd Bean shaped. The fruit comes from unique, beautiful purple-maroon flowers in late spring. The Paw Paw's maroon-purple blossom, while beautiful, is said to smell like rotting meat. Interestingly, bees and other insects show little interest in the pawpaw flower, and the main pollinator insects are flies and beetles.

The Paw Paw fruit has the flavor of a cross between a banana, papaya, and a mango. The fruit has also acquired the nickname of the "custard apple, “poor man's banana", and "Indiana banana.". The Paw Paw fruit has yellow-green skin and soft, orange flesh with a creamy, custard-like consistency and a delicious, sweet flavor. The Paw Paw fruit's popularity with locals is due to its delicious flavor with an added bonus of its rich nutritional value. Paw Paw is reportedly high in protein, antioxidants, vitamins A and C, and several essential minerals. The Paw Paw fruit doesn't travel well as it bruises easily and has a short shelf life (two to three days at room temperature).

The Paw Paw is often thought of as a small, understory tree. It can become a sizeable growing shade tree and is quite adaptable to many locations in Ohio. The appearance of this tree gives a tropical flavor to temperate gardens and provides edible landscaping.

Planting Requirements

Naturalists have noted the expansion of pawpaw from well-drained, lowland habitats into drier, upland forests in recent decades. Paw Paws often grow in humid climates and are highly frost tolerant. Paw Paw often grows in the shade in open woods, usually in wet, fertile bottomlands, but can grow in upland areas on rich soils. Paw Paws often occur as understory trees in an oak-hickory forest in the midsouth where they are found in clusters or thickets.

Pawpaws can serve as a screen or can be grown in a container as a specimen tree. Both trees and shrubs have a conical pyramid-like shape when grown in the sun and a more open structure if grown in the shade. They can be planted in the shade of tall, open trees or partial shade, although they fruit best in the sun. If planting in the open sun, provide a shading structure to allow filtered sun for the first few years. The plants prefer moist, slightly acidic soils and require regular watering, but are adaptable to many conditions. They do not perform well in poorly drained soils and need protection from the wind. At least two plants are needed for cross-pollination.

Transplanting seedlings of Paw Paw's should occur in the spring. Larger plants of Paw Paw do not transplant well. Paw Paw's roots are widely spreading, so purchase plants that have been grown in deep pots or tubes to ensure healthy plants. The roots are brittle, so use care when transferring from containers.

Vegetative propagation: Paw Paw's by seed and can be propagated by whip-and–tongue, bark inlay, cleft graft, or chip budding techniques.

Daily watering is necessary for the first few weeks following planting. After one month, watering should be reduced to two times per week and continue for one year. The establishment takes 6 to 12 months for each inch of trunk diameter. Larger trees benefit from irrigation during the second year, and after that, if site conditions become dry.

Property Maintenance and Public Safety

This plant spreads quickly by suckers to form a "pawpaw patch." Remove suckers as they form if a tree form is desired. Sucker formation slows as the tree develops. Other than control of suckers, the plants do not require pruning. The plants are disease and pest resistant, and deer do not browse them.

Don't install this tree in frequently used pedestrian areas associated with sidewalks, patios, and driveways due to the fallen fruit's slip hazards. If Paw Paw is installed in a high use area, then will site maintenance may be required to reduce the risk of slips and falls due to the fruit.  

Check with a local Ohio International Society of Arboriculture Certified Arborist for what cultivars will work in your location.

Cultivars

This tree species and its various cultivars are often sold and are available from nurseries throughout the Ohio region, and it transplants easily in the spring of the year. Check with a local Ohio International Society of Arboriculture Certified Arborist for what cultivars will work in your location.

'Allegheny' is a precocious (bears early in the tree's life), productive tree. This fruit is a favorite of many consumers. The skin stays purely green at ripeness.

'Davis' is reliable and productive and produces large amounts of large, high quality, sweet fruit.

'Mary Foos Johnson' is a cultivar that originated in Aurora, Oregon and is considered closely related to the cultivar 'Sunflower,' which is self-fertile and has fruits that mature in late summer, 2-5" in length and weigh up to around one-half pound.

‘Overleese' are a parviflora is a dwarf variety of Paw Paw.

'Potomac' is a sister variety to Susquehanna with even larger fruit. Originated from an orchard near the Potomac River.

'Rappahannock' is an unusual pawpaw tree because it holds its leaves horizontally. The pulp is a brighter yellow. The flavor is medium with a simple, clear flavor.

'Shenandoah' – known for good yields, mildly sweet flavor, with only 6% seed with as succulent, custardy texture.

‘Susquehanna’- produces large fruit with extremely few seeds and firm melting texture. Quite sweet with a strong pawpaw flavor.

'Sunflower' is a reliable and productive variety that offers Paw Paws with greenish-yellow skin, buttery flesh, and only a few seeds.

'Tallahatchie pawpaw' is known for producing good yields of fruit medium to large with exquisite taste sweet, perfect balance of flavors and ripens in midseason.

'Taylor' is a productive and early ripening variety and produces abundant crops of sweet and delicious fruit with light yellow flesh. Taylor Pawpaw often bears striking clusters of up to seven fruit.

Wabash- developed by Dr. Kirk Pomper at Kentucky State University, has a sweet and rich flavor. Texture medium-firm, creamy, smooth. Flesh color yellow to orangish.

Environmental Importance

Many native insects and other biological components rely on the Paw Paw. The Paw Paw is a favorite host plant of the Zebra Swallowtail Butterfly (Protographium marcellus). The Zebra Swallowtail larvae feed on the leaves of the Paw Paw without causing harm to the plant. Other animals like opossum, raccoon, foxes, and squirrels eat the fruits of the Paw Paw.

Ethnobotany

Historically, the fruit was had has been enjoyed by Native Americans and early European settlers alike. At least two U.S. presidents favored Paw Paws: George Washington reportedly enjoyed them for dessert, and Thomas Jefferson was known to have grown Paw Paws at Monticello, Virginia. Today the Paw Paw, which often grows along the banks of rivers and streams, is a convenient snack for hikers, kayakers and a staple in the autumn diets of many who enjoy its unique flavor.

Some Native American tribes cultivated the Paw Paw for fruit and are responsible for its wide range today. The Cherokee and many other tribes used the pawpaw fruit is high in amino acids. The Iroquois used the mashed fruit to make small cakes that were dried and stored. The dried cakes were soaked in water and cooked to make a sauce or relish served with cornbread. Raw and cooked fruits were dried by the sun or on fire. These were stored for use in the future or taken on hunts. The Cherokee used the inner bark to make cordage. By twisting the bark, they made string and strong ropes. Other: The twigs and leaves contain extracts that have insecticidal properties. The leaves contain anticarcinogens.

​Tree Selection Tips

The Ohio Chapter ISA recommends working with an ISA Certified Arborist when selecting or caring for any tree in your landscape. To better guide you on the vital plant information for the Paw Paw use our friendly users guide below:

Written by Mark A. Webber BCMA, CPH, LTE,  MArborA, OCMNT, TRAQ, TPAQ

Literature Sources:

Bailey, L.H. & E.Z. Bailey 1976. Hortus Third: A concise dictionary of plants cultivated in the United States and Canada. Simon and Schuster Macmillan Co., New York, NY. 1290 pp.

Banks, W.H., 1953. Ethnobotany of the Cherokee Indians. Master of Science Thesis, University of Tennessee, Tennessee. 216 pp.

California Rare Fruit Growers, Inc. 1999. PawPaw Fruit Facts. (April 29, 2001).

Flint, H.L., 1997. Landscape plants for Eastern North America. Second Edition. John Wiley and Sons, New York, New York. 842 pp.

Greene, W.F. & H.L. Blomquist 1953. Flowers of the South: Native and Exotic. University of North Carolina Press. Chapel Hill, North Carolina. 208 pp.

Hamel, P.B. & M.U. Chiltoskey 1975. Cherokee Plants and their uses: A 400-year history. Herald Publishing Company, Sylva, North Carolina. 65 pp.

Hann, J.H., 1986. The use and processing of plants by Indians of Spanish Florida. Southeastern Archaeology 5(2):91-102. Hummer, K. 1996.

NCGR-Corvallis: Pawpaws in Oregon. (April 29, 2001).

Martin, A.C., H.S. Zim & A.L. Nelson 1951. American wildlife and plants: A guide to wildlife food habits. Dover Publications, New York. 500 pp.

Moerman, D.E., 1998. Native American ethnobotany. Timber Press, Portland, Oregon. 927 pp. Ottesen, C., 1995. The native plant primer. Harmony Books, New York, New York. 354 pp.

Podems, M. & B. Bortz 1975. Ornamentals for eating. Rodale Press, Emmaus, Pennsylvania. 67 pp.

Pomper, K., S.C. Jones, R.N. Peterson, T.Turner, & D.R. Layne 1990. Paw Paw Planting Guide. Kentucky State University Cooperative Extension

http://www.botany.hawaii.edu/faculty/carr/annon.htm (collected on December 28, 2020)

https://www.nps.gov/articles/pawpaw.htm (Collected on December 28, 2020)

Kain, M., Battaglia, L., Royo, A., and W.P. Carson. 2011. Over-browsing in Pennsylvania creates a depauperate forest dominated by an understory tree: Results from a 60-year-old deer enclosure.

http://entnemdept.ufl.edu/creatures/bfly/zebra_swallowtail.htm (Collected on December 28.2020)

https://www.livescience.com/34669-what-is-a-paw-paw.html (Collected on December 28, 2020)

https://www.starkbros.com/products/fruit-trees/pawpaw-trees/sunflower-pawpaw (Collected November 20, 2020)

https://www.petersonpawpaws.com/pollination#:~:text=Pawpaw%20blossoms%20are%20designed%20by,flies%20to%20your%20pawpaw%20trees. (collected on December 28, 2020)

https://plants.usda.gov/plantguide/pdf/cs_astr.pdf (Collected on November 20, 2020)

https://onegreenworld.com/product/davis-2/ (Collected November 10, 2020)

https://dawesarb.arboretumexplorer.org/taxon-20111.aspx (Collected December 28, 2020)

https://www.gardeningknowhow.com/edible/fruits/pawpaw/insects-that-eat-pawpaws.htm#:~:text=The%20most%20damaging%20of%20the,drop%2C%20thus%20lack%20of%20fruit. (Collected on December 28, 2020)

Photograph sources Mark A. Webber 2020-2021