dand said:

I live in Taylor, Michigan, which is near Detroit. At the rear of my
back yard, growing in the brush at its edge, is a beautiful tree, about
ten or twelve feet tall, that looks to me like a cherry tree, but it
doesn't have cherries on it. It has groups of small (about a quarter
inch diameter) smooth, round berries that are very dark -- almost black
in color. I squashed one between my fingers and got a rich purple juice
out of it that had no odor I could detect. No, I didn't taste it.
Here we are in late October, and there are all kinds of these berries
to be seen, and it seems nothing's interested in eating them. Could
somebody tell me what kind of tree I have?

One possibility is one of the invasive buckthorns (Rhamnus sp.), which are
ripe now. These sometimes go by the name 'tallhedge' and are the objects
of many workdays in Nature Conservancy reserves.

common buckthorn:
http://www.nps.gov/plants/alien/fact/rhca1.htm
http://www.dnr.state.oh.us/forestry/.../buckthorn.htm

glossy buckthorn:
http://www.uwgb.edu/biodiversity/her...s/rhafra01.htm
http://gallery.cs.umb.edu/gallery/Glossy-Buckthorn

Buckthorn berries are not edible, though they have been used medicinally.
The berries can be toxic to some people (most dangerous to children, due
to their small size), though fatalities are very rare.

"Buckthorn berries (Rhamni baccae) are powerfully cathartic; 20 of the
recent berries cause brisk, watery purging, with nausea, dryness of the
throat, thirst, and tormina."
http://www.ibiblio.org/herbmed/eclec...mnus-cath.html

tormina = acute, colicky pains; gripes
--
Pat in Plymouth MI ('someplace.net' is comcast)

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)