Sounds like a catalpa, although the Kawartha Lakes are far beyond its
natural range. According to Hosie (Native Trees of Canada) they don't
occur here. I've seen a number of large specimens in Toronto, so
perhaps someone planted the ones you saw, and they are hardier than one
might expect.

In article ,
Bonnie wrote:
While cottaging at a lake near Apsley last week, we saw several of
these trees. The leaves are rather sparse, medium green, large (3+
inches), spade-shaped/triangular. Not smooth.(I think a bit serrated
as well, but my memory's shaky on that point.) The trees were fairly
tall, say 20 feet or so.

What was most noticeable, however, were the beautiful flowers. Almost
orchid-like, somewhat cup-shaped flowers, mainly white, with
purplish/reddish colouring inside. These were growing in loose
clusters. Each bloom was about one inch (more or less) in diameter.
Colouring and semi-closed opening in the bloom reminded me a bit of a
snapdragon.

I've searched a lot on the Internet, and just cannot figure out what
they were.

Would greatly appreciate your thoughts.

Thanks!