Trees with a little more here and there. Swiss. Painted by Adolf Dietrich (1877-1957). One of the most renowned of what are referred to as naïve artists.

"Marder im Winterwald / Marten in the Winter forest." 1937. Oil on cardboard.
“Marder im Winterwald / Marten in the Winter forest.” 1937. Oil on cardboard. © Estate of the artist. Fair use license. via
Dietrich, Waldren at Langenagen 1917
“Waldren at Langenagen.” 1917. © Estate of the artist. Fair use license. via http://art-now-and-then.blogspot.com/2013/06/adolf-dietrich.html
"Vorfrühling" (Early Spring). 1933.
“Vorfrühling” (Early Spring). 1933. © Estate of the artist. Image © 2019 MCH Group | Curiator . Fair use license. via https://curiator.com/art/adolf-dietrich/vorfruehling-early-spring