The fabric appears to be a slubby linen look fabric. Definitely not real linen. There would be many more wrinkles.
Click on the pictures to make them larger. When you do you can see that there is also some beige stitching that looks like basting stitches all along the sleeves, however, I think it is just decoration.
I love the buttons on the sleeves and the beaded trim all along the edge of the sleeves.