n England now it is the time of year that some lime trees have their
wonderful scent. Only some though, which makes me think that it may be
a different species that has the scent from the common lime. These
trees seem to have a darker leaf color than the common lime.

I assume you mean lime as in linden, the symbol of Czechoslovakia. I've never
seen sap under them, but they do attract a lot of bees for the nectar.
zemedelec