What is the shape of a palm trees leaves?

There are several variations on the shape of palm fronds. All have a stiff stem, usually roughly triangular, with a fan of leaf blades growing from the stem. In some, the fan radiates from a short segment of the end of the stem, while in others, the structure of the frond is like a feather, with blades attached to the stem at regular intervals, getting shorter and shorter as they approach the tip.