In message , Allan Adler
writes

I can sometimes identify plants with the aid of a field guide
and sometimes not. Sometimes leaves and other stuff from the plant
falls on the ground and is easily collected for its own sake, just
to have a record of what I found. I own a microscope which can give
magnification from 50X to 675X. I don't have a laboratory and am
certainly not going to try doing DNA sequencing. I'm just wondering
whether there are easy ways to distinguish, say, different trees by
looking at parts of them (e.g. leaves) under a microscope. E.g. maybe
their cells look different?

There are certain traits which are correlated with ploidy level (e.g.
size of stomata, size of pollen grains). These could be used to
distinguish cytotypes.

I suspect that in some groups examination of trichomes can distinguish
non-flowering material of related species. (At the right time of year
one can distinguish material of Tilia platyphyllos and Tilia x vulgaris
from the texture of the leafs; the pubescence of the former is not
always visible to the naked eye, but can be detected by touch.)
--
Stewart Robert Hinsley