OpenGL create trees

I am using PyOpenGL with PyGame (although I am also trying to copy the game into c++ as well), and I would like to draw some low-poly trees in my game, something like the one in the picture below.

But at the moment I only know how to draw simple flat surfaces and put textures on them (by creating an array of x,y,z coordinates and texture coordinates and using glDrawArrays). Is there a way to make something like the tree below using only opengl (would it involve 3d texture coordinates?) or do I need an external graphics engine?

If I do need a graphics designer, does anyone have any recommendations, and then am I right that I would need to pass the vertices to an array in python and then use that in glDrawElements?

After some point, you cannot handle complex objects by just defining 3D vertexes in Opengl. Instead you need object model that you can include it to your project. Most of the objects models are come with their texture files and texture coordinates included so you don't need to worry about texturing them.

For loading objects into your scene, I suggest you to use assimp library. And after you setup your environment, only thing you have to do is search for free low poly tree models. Here is a webpage that you can find free low poly trees : http://www.loopix-project.com/