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Pawpaw mystery

A strange thing happened at the Annapolis Royal Historic Gardens this summer. The resident pawpaw tree (Asimina triloba) bloomed and produced fruit. The occurrence is unusual for two reasons.

A pawpaw tree at Annapolis Royal Historic Gardens produced fruit this summer. Trish Fry photo

Firstly the fact that this tree even survives in the garden is notable. Although they are indigenous to 26 states in the U.S., in a range extending from northern Florida to southern Ontario, one doesn’t normally think of pawpaws in a Nova Scotia orchard. However if they did become established, their custard-like texture and tropical tasting flavour - a blend of banana, pineapple, and mango - could become a big hit.

Secondly, these trees usually need two specimens to set fruit.

I emailed Ron Powell, president of the Ohio Pawpaw Growers Association to see if he had an explanation for the event.

He says usually pawpaws do need two trees to set fruit and that they have several things going against them for self-pollination. The female part (stigma) of the flower matures before the male part (anther). The flowers are perfect in that they do contain both female and male parts. “The plants are self incompatible, thus you need a second tree for pollination,” he said.

Pawpaws grow in patches, spreading mostly by root suckers, and those trees would all be considered to have identical genetic material and thus cannot pollinate other trees in the patch. However, there is some evidence, not scientifically verified, that some trees do self-pollinate explained Powell. “One variety ‘Sunflower’, may be able to self pollinate,” he added.

I also contacted Dela Erith, executive director of the Nova Scotia Fruit Grower’s Association, to see if she had any theories on the “virgin birth” of this pawpaw fruit. She sent the request on to Desmond Layne who is a pawpaw expert at Clemson University in South Carolina. He agreed with Powell that pawpaws require cross pollination and suggested that there might be a wild tree somewhere that Historic Gardens staff might not be aware of. “Although some reports of successful self-pollination have been made by enthusiasts, there is no scientific verification to that fact that I am aware of,” said Layne, who is a native of Harrow, Ontario where he says pawpaw grows wild in Essex county near his home. There are commercial fruit nurseries in the Niagara region that grow and sell pawpaw trees.

Layne says he would imagine that Nova Scotia would certainly be at the northerly range of where pawpaws could be grown successfully. “There are cold-hardy cultivars that have been developed and selected in Michigan and upstate New York that might be appropriate,” he said.

The unusual tree is generating interest amongst horticulturists who hear about it’s fruiting in Nova Scotia. Who knows? Perhaps bananas and pineapples aren’t too far behind?

Next week: Another top five fall favorites.

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