Tom Wagner mentioned a trait he called "narrow leaf".
(I wonder if he means wispy, droopy foliage like many hearts
have or what some call "carrot leaf", like Silvery Fir Tree.)
I think what we are discussing here is mostly "type 3" on this
page:
http://www.tomatoland.net/forums/viewtopic.php?p=218
These pictures of Kosovo from Tania's TOMATObase kind
of show it:
http://tatianastomatobase.com/wiki/Kosovo
Looking at the Kosovo pictures, it looks like a characteristic
of the stems, as otherwise the leaves look fairly normal
for a regular leaf plant. That is consistent with what
I have seen, which is why I called it "droopy leaf".
That would fit with a "wispy" potato leaf plant. The leaves
do not seem to "reach for the sky" nearly as much as
plants that do not have this characteristic. The stem of
the rachis bends down.