Roman clothing owed much to that of ancient Greece, but it had distinct forms of its own.
In all the ancient world, first and foremost clothes needed to be simple. As for possible materials there was only really one. Wool, although to some extent linen was also available.
The needles of the day were coarse and unwieldy by modern standards. Hence any stitching or sewing was kept to a minimum.
This of course also ruled out button holes, and meant that any kind of clothing was held together either with fastenings such as broaches or clasps.