Thanks bunches Jim Carter and zxcvbob!

Your combined remarks left me a bit confused (I am certainly no
expert). On the one hand, Jim is claiming that tomato (presumably it
is same for tomatillo) is "self-pollinating". On the other, zxcvbob
says they are "self-sterile". These seem diametrically opposed. My
understanding (maybe wrong?) was that pretty much all plants in the
tomato/tomatillo family (many different food plants) must be cross-
pollinated. To me, this means at least two plants of same variety
are needed. Pollen from plant #1 pollinates plant #2, but plant #1
cannot pollinate itself, etc. Am I missing something?

Within similar discussion, reading up lately on bees, I learned that
many plants are wind-pollinated or that bees cannot access the nectar
or the nectar is not of a type interesting to the bees, so other
insects end up pollinating the flowers. Other times, there is simply
the matter that bees already found plenty of nectar from other nearby
flowers and have tendency to stop exploratory behavior once they find
a plentiful source they are happy with. In many such cases, insect
pollination is not critical. Upon examining my tomatillos
more closely, like when trying to cross-pollinate with a brush, I
found that the pollen is quite small and easily made airborn,
suggesting wind pollination is possible. The pollen is readily
accessible due to the flower geometry, but bees mainly ignore the
flowers. Other insects, especially some butterflies, have thus far
spent considerably more time actually landing on the flowers and
accessing nectar. Interesting point, there were a number of bee
exploratory events, but it was clear they were not actually stopping,
landing and accessing nectar. So the question comes up, what are
typically the dominant mechanisms for tomatillo pollination?

Finally, nomenclature question. When I say "cross-pollinate", I am
meaning crossing two separate plants with separate roots, stems, etc,
but exact same variety of tomatillo. Is this correct terminology? I
presume if crossing with different varieties, one would say they are
hybrizing or some such. Not sure about these details.

I have already asked a few questions. I'll stop here.

Dominic