Interspecies Asimina (pawpaw) crosses

I have some documents to share on this subject from multiple researchers, perhaps other folks here can contribute some too.


The oldest I have on hand is this 1941 article by G. Zimmerman in Journal of Heredity. I believe a Xerox copy of it is also included in the CRFG '74 Yearbook.

Zimmerman 1941 - Hybrids of the American papaw.pdf (3.9 MB)


Wow. Thank you @Richard.

Extremely interesting to read Zimmerman’s observation of poor natural pollination and great hybrid potential. I have essentially zero natural pollination in my small grove of six trees containing 19 varieties with 15 foot spacing.

Zimmerman is the first breeder I’ve seen target self-fertility or fragrant blossoms as a breeding goal. I second the motion to pursue this.


The Zimmerman article is of interest for many reasons, for example he mentions D. Fairchild.

If one goes to Google Scholar ( and searches on the title of Zimmerman’s article, you’ll find it plus articles that cite it. Most importantly, somewhere buried in there is one labeled “[CITATION]” like this:


If you click on the “Cited by” link that I circled, you can get a list of all the citations Google “knows” about. Here is that link:,5&hl=en

From there you will find “new” articles of interest, and some not so interesting. But staying on the track of Asimina hybrids, your next step is to look at the relevant articles and their references!

From those references, find all the ones that concern Asimina hybrids (you might have to read several to find out). This could take a few days … or weeks. Now you have some new “historical” references. But wait, you are not done!

  1. Go back to Google Scholar. Look up each of these “new” articles and find their citations - as I did above for Zimmerman. You now have more “new” articles!

  2. Also, go back to Google Scholar. Look up each of the “historical” articles you discovered and find their citations. Now this is going to take awhile.

Then repeat steps 1 & 2 as many times as necessary until you cannot find any more “new” or “historical” articles regarding Asimina hybrids. Now you have researched the topic.

BTW, as a historical (!) note: this is how topics were researched before the internet. But instead we went to a university library to the reference floor and did this searching manually through published citation indexes. They still exist!


Re: insect pollination, it puzzles me that Zimmerman observed little natural pollination 80 years ago. Back then we had far more insects, far less development and habitat degradation. Everything about pawpaws is strange.

It takes a period of years for local pollen beetles to learn there’s a new plant in town. My dragonfruit for example took about 4 years. Also, they are not all from one species and its important to know they are tiny, usually half the length of a small Argentina ant.

Hi Richard, how do insects not within the range of a species become a pest at a landscape? I’m curious your thoughts about two bad ones with Carya: Hickory Shuckworm and Pecan Weevil. Even though I am within the range of all three of the big ones for fresh eating… Carya ovata, Carya illinoinensis, & Carya laciniosa… there aren’t any of them within possibly 10 miles that I can think of.

Once they infest a landscape (my current 6-acres for example) - you always have them. Something - in addition is that hican (shagbark or shellbark x pecan) or plain old hickory will bring in both those “short distance flier’s” - and then what (anyone is left with …) are pecans.


Does yours get many flies?This year,there seemed to be one in every other flower,on an Overleese.


That question is out of my range :flushed:

Apparently I have no pollinating insects here. Some nearby landowners spray for mosquitoes I wonder if that has an effect

I’m going to bounce that off another guy, very similar to you, that I know who actually happens to grow pecans in the northern Redwood’s of Cali.

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Here’s his explanation.

I’ve wondered and asked about this issue in California commercial and private growing of pecans. Currently this is not an issue. The explanation I have heard is those two bugs 🐛 do not survive in this habitat. Thank the stars for that. It’s like the plum and apple curculio that devastates in the east does not live here. Of course these creatures have gotten here by now.

It’s the dry long low humidity summers that certain animals do not survive in, however there are many that do.

I had the same situation with my Apple 🍎 orchard. I am located 6 miles away from the nearest apples infected with codling moth. It took about 30 years to get here but it did.

I think the neighbors about a mile away had the habit of harvesting apples with the pest in them and composting the bad ones and then there few trees became infected.

Now who knows with the changing climate, what will happen.

Ok, well back to the topic of Asimina hybrids. What documents of interest have you folks found in the link I gave above - esp. those you couldn’t find a free copy of?,5&hl=en

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From the Abstract:

“In regard to pollination, many primitive Angiosperms have maintained the archaic condition of cantharophily, because beetles are still a dominant insect group, whereas in dispersal they have been largely forced to switch over from the archaic saurochory to the more modern modes of dispersal by birds and mammals, since during the later Mesozoic the dominance of reptiles had come to an end.”

Gottsberger 1974 - The structure and function of the primitive Angiosperm flower.pdf (927.4 KB)

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The World Was My Garden, David Fairchild 1938


I never cease to be amazed by the breadth of D. Fairchild’s research of plants.

An amazing fellow. Would love to have met Frans Meijer.
I hope to visit the Kampong someday.


Check out W.T. Swingle.

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I spoke with Richard Campbell 2 weeks ago,
If David Fairchild did any work with Asimina Triloba aka PawPaw he has no idea where the trees are.
The Fairchild pawpaw offspring of 1916 winner as well as any pawpaw crosses or interspecific hybrids are not nor ever have been at Fairchild in Florida.
I’m going to by attempting to adapt Asimina Triloba to the Sonoran Desert via wild yeast symbiosis & breeding. Plus interspecific hybridize any success with other annona species.

D. Fairchild’s work with Asimina and the fate of the plants is well-documented.

In my experience, the scouring of published research is more fruitful than sole reliance on gossip.