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Pawpaws, also known as Asimina triloba, are Ohio’s official state native fruit and are recognized as the largest edible fruits native to North America. Found exclusively in southern Canada and the eastern United States, this fruit is loved by many for its custard-like texture and sweet tropical flavor. Unlike their plant relatives in the Annonaceae family, which are tropical and sub-tropical species, pawpaws are deciduous and live in temperate regions, like Ohio! These charismatic and aromatic fruits have a harvest season that ranges from late August through the end of September. The first fruits have started to ripen on pawpaw trees within the Zoo, at Bowyer Farm, and at community gardens like Rockdale Urban Learning Garden, which means that pawpaw season has officially started in Cincinnati!

While Asimina triloba is the pawpaw species many people know and love in Ohio, there are several other species of pawpaw found throughout the United States. Beautiful pawpaw (Deeringothamnus pulchellus) and Rugel’s pawpaw (Deeringothamnus rugelii) are both endangered species endemic to Florida. Largely at risk due to habitat loss and degradation, D. rugelii and D. pulchellus are considered exceptional species, meaning that they cannot be conventionally seed-banked and thus require an alternative approach for ex-situ conservation. The Plant Division at CREW has partnered with Bok Tower Gardens in Florida to improve methods of conserving these imperiled species (see past collaborative research efforts here and here). Their strategy consists of using in-vitro tissue culture techniques to initiate new samples of D. rugelii and D. pulchellus collected from the wild. CREW scientists will then use these plants to test different methods of cryopreservation, which involves using liquid nitrogen to rapidly freeze plant tissue so that it can be stored long-term in banks like CREW’s CryoBioBank. After freezing, the plant samples will be recovered and regrown again in culture.

Eventually, the plants will be transitioned from growing in a test tube to growing in soil through a process called acclimatization. Optimizing these steps will guarantee that D. rugelii and D. pulchellus can be safely stored long-term and regrown into healthy plants that can be used for restoration projects in the future!