There are at least 2 clones of Hoya undulata. One of them has much smoother edged leaves that is wider and somewhat shorter. The original one from Borneo has longer, wavier leaves, that get extremely red under good lighting. It is this original one that is so difficult for me to grow well. It is many times harder to grow than the smooth-edged clone. Anyhow, I have buds on the difficult to grow one that actually look pretty good. Pictured below: