Are involuntary muscles striated?

No. The involuntary muscles of the muscular system are not striated or furrowed.

These muscles that are not striated are very smooth to the sight which is why they are also called Smooth muscles. Involuntary muscles are not striated. Even among the striated muscles that are voluntary, the heart which is also a muscle, is involuntary.

On the other hand the striated muscles, which are voluntary are highly fibrous and their primary function is to move the body voluntarily, and producing heat as a result of this muscle action.