The wheaten pullet, also shown below, doesn't have willow legs, but the shadow on her back leg may make it look that way on your monitor. If you look at her front leg, it is slate. That pullet is only 8 weeks old in that picture.
Wheatens and blue wheatens have the lightest colors shanks when they are young and they darken as they grow older. Depending on the age at the time the picture was taking, it can range anywhere from the a lighter slate, almost pinkish cast when very young, to the full slate. In my five years of raising wheatens and blue wheatens, I've yet to see one with the really dark shanks of, say, the whites.