American landscape painter Frederic Church was best known for his paintings of South America. Many of them were actually painted at home in New York. They were based on sketches he made during his travels in 1853 and 1857. Some of those sketches were done in oil paint, and some laid out whole scenes. But he also covered page after page with little pencil drawings.
A typical sketch page looks like this; the main subjects, at least of the pages I have seen, are plants and buildings.
Church's trees are nothing like the generic trees that often populate landscapes; these are individual portraits of particular living things.
Colombian street scene.
And one from North America, a view of Mount Katahdin, from about the point where I camped when I climbed it.
I could look at these all day. So of course I tried to find more online than what wikipedia has. Sadly they all seem to be in the Cooper Hewitt collection of the Smithsonian, whose web site is giving me nothing but error messages and "Gateway Time-out." So that will have to wait until another time.