Asimina triloba - pawpaw

In the book 'Trees Of The Carolinian Forest - A Guide To Species, Their Ecology & Uses' by Gerry Waldron he says that in sand pawpaw "grows with beech, sugar maple, sassafras, red maple, butternut, tuliptree, white ash, witch-hazel and spicebush".  On clay soil "it associates with black walnut, white elm, burr oak, bitternut, Shumard oak, red ash, black maple and sycamore".

Hand pollinating pawpaws (Asimina triloba) is a quick, fun springtime chore.
 

A five year old pawpaw in bloom, April 19, 2011 in Bowie, MD. I grow three Neil Peterson-selected cultivars: 'Shenandoah', 'Rappahannock' and 'Susquehanna'. Note immature greenish flowers and burgandy-red mature flowers.
 
I use a small paintbrush and bowl for hand-pollinating pawpaws. I never notice the smell of pawpaw flowers except when I'm hand pollinating, when it does get a little stinky! Pawpaws smell like carrion in order to attract pollinating flies, but they don't attract many, which is why people hand pollinate.
 
As pawpaw flowers mature, they are first female and then male. The female flower is shown above. Note the sticky green-yellow stigma in the middle, where pollen is placed.
 
A male pawpaw flower is shown above. Note the ball of brown, dusty pollen. Some people pick a male flower, pull off the leaves and touch it to female flowers to transfer pollen. I find it easier to use a brush and bowl because I can pollinate more female flowers at once.
 

 
I use the back of the paintbrush to knock pollen from several male flowers into the bowl.
 
It doesn't take long to collect enough pollen for many female flowers. (The yellow flowers on the ground are Green and Gold, Chrysogonum virginianum.)
 
Pollen on the paintbrush, ready to transfer to the female flowers.
 

Gently brushing pollen onto a female flower. It only takes a little pollen. As Eric noted, pawpaw trees are not self-fertile; pollen must be transferred to the female flowers of a different pawpaw tree. If you are growing several "copies" of a particular cultivar such as 'Shenandoah' like I am, the pollen must come from a different cultivar.
 
Success! Four weeks after pollination, tiny fruits are starting to form. September is going to be luscious!

Your picture inspired me, and I'm thinking of planting black locusts around some 4-year-old pawpaw trees.  1.  Why are the benefits so "awesome"--more fruit due to high locust-fixed nitrogen? 2.  Is there any rule of thumb for how closely to plant the black locusts to the pawpaws? 3. And, finally, uses: I assume that you also coppice the black locust for chop-and-drop fertilization, right? Any other uses that you have made of the black locusts?
Thanks,
TG
Cleveland Heights, Ohio

Deer apparently won't eat pawpaw, so in coastal Maryland at Ecosystem Farm (www.accokeek.org) where there are tons of deer there is almost nothing there but pawpaw. We talked at lot about topworking (grafting) the wild pawpaws with improved varieties, and improving yields on wild and grafted pawpaws with hand pollination. Wild polycultures of note included: black locust-pawpaw (awesome), and mulberry-pawpaw (also interesting). Both are profiled as polycultures here on Apios.

Here are some fotos of pawpaw in its natural habitat (but with unnatural deer pressure).

Under black locust:

Small suckers grow quickly to take advantage of a forest gap where a large tree came down:

General pictures of pawpaw understory:

Not quite our largest, I think the related pond apple (Annona glabra) is larger. But it tastes terrible!

Pawpaw is really great tasting and I can't believe it is not more commonly grown. Virtually no pest problems, in fact many relatives are used to make pesticides in the tropics.

Forms colonies which can live for thousands of years, though individual trees not so long.

Creamy, sweet, rich. Needs hand-pollination, I'll try to post a video about that next spring.