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Home / Blogs / What’s Poppin’? Phenological Fun: Paw Paw
May 7, 2024
Pawpaw (Asimina triloba) flowers (Photo credit: Rob Frank, ACB).
I get the greatest joy in letting people know about the odd and less appealing intricacies of biological function so it just made sense that I get to tell you about paw paw flowers. There has been a notable increase in attention to paw paws (Asimina triloba) in the last decade or so, which is great for native trees as a whole! Another growing area of enthusiasm is for pollinators, which is great for insects as a whole! But what Big Paw Paw’s and Big Pollinator’s marketing team leaves out is just how the sausage-shaped fruit is made.
Pawpaw (Asimina triloba) fruit (Photo credit: Rob Frank, ACB).
Like a lot of fruiting trees, a paw paw cannot produce fruit on its own. Kentucky State University Cooperative Extension explains it this way; “The flowers are protogynous, meaning that the stigma (the female receptive organ) ripens before the pollen, and is no longer receptive when the pollen is shed. Thus the flower is designed not to be self-pollinated. In addition, paw paw trees are self-incompatible, usually requiring pollen from a genetically different tree in order to be fertilized.” Combine this with the tree’s tendency to grow from root suckers and we understand why we sometimes encounter large groves of paw paw trees that don’t produce fruit- it’s all one plant!
Pawpaw (Asimina triloba) flowers with fly pollinators (Photo credit: Rob Frank, ACB).
So where do little paw paws come from? The short answer is pollinators, but, in the instance of the paw paw, it isn’t the charismatic bees, butterflies, and hummingbirds that we so strongly associate with that term. Paw paws have their flowers fertilized primarily by flies and beetles. In people who aren’t me, flies and beetles don’t usually engender strong positive responses, which is tough, because together they make up over one third of all described species on this planet (Earth). The smell of a paw paw flower, while nearly imperceptibly faint (you really have to get in there), can be described as over-ripe, rotten, or putrid which is just what those ancient workhorse insect orders love. Beetles and flies have been pollinating flowers longer than other pollinators have even existed, so next time you are enjoying a paw paw, think of all the flies and beetles that crawled all over those flowers to make your treat possible! However, if you still need a pretty butterfly, the paw paw provides that as well. Paw paw’s are the host species of the Zebra Swallowtail butterfly. This tree has something for everyone!
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