For this tutorial, #371 gold wire was used to create a leaf motif.
It could also be used to create veins on a leaf worked in silk, as shown below.
Start out with a few Reverse Chain stitches (reference Reverse Chain tutorial if you aren't already familiar with this stitch).
As you create each loop or chain, increase the distance between the legs as shown here.
Keep a firm, but not tight, tension. Pull only enough to keep the "legs" straight.
If creating a shape such as this one, you will begin to reduce the length of the legs as you come to the final point and the last stitch will be a Reverse Chain.