There was his angry scowl, ①his vain

There was his angry scowl, ①his vain heap of hair, his big fist grasping the whip,
his twisted mouth swearing vengeance.

①his vain heap of hair, とはどういう意味ですか？ここでの vain や heap はどういう意味で使われていますか？

よろしくお願いします。