Doctor Dolittle in the Moon by Hugh Lofting

Indeed our first close acquaintance with the forests of the Moon was made in quite a dramatic manner. If it had been on a stage it could not have been arranged better for effect. Suddenly as our heads topped the bluff we saw a wall of jungle some mile or so ahead of us. It would take a very long time to describe those trees in detail. It wasn't that there were so many kinds but each one was so utterly different from any tree we had seen on the Earth. And yet, curiously enough, they did remind you of vegetable forms you had seen, but not of trees.

For instance, there was one whole section, several square miles in extent apparently, that looked exactly like ferns. Another reminded me of a certain flowering plant (I can't recall the name of it) which grows a vast number of small blossoms on a flat surface at the top. The stems are a curious whitish green. This moon tree was _exactly_ the same, only nearly a thousand times as big. The denseness of the foliage (or flowering) at the top was so compact and solid that we later found no rain could penetrate it. And for this reason the Doctor and I gave it the name of the _Umbrella Tree_. But not one single tree was there which was the same as any tree we had seen before. And there were many, many more curious growths that dimly reminded you of something, though you could not always say exactly what.