Each member of one direction has a very iconic hairstyle. For example, Harry styles has VERY iconic hair because it is so pouffy and well, big. Some might call Harry's hair an Afro, but it really isn't. It's just a mop of curls swept to one side! When he was born, is hair was white-blonde and curly. Harry is currently a brunette. It has gone through many other phases, including a time when is well-known curly locks were straight. I think harry's hair is the most iconic out of the band besides niall's blonde hair.
Liam Payne's hair has gone through many different styles and cuts since he was on x-factor. At the beginning, his hair was like Justin bieber's old 'do. It was all straight and swept to the side. Then his hair was sort of like harry's, all curly and such. Currently, he leaves his hair in it's natural curly state, but it's much madami tamed and not all big.
Niall horan has hair somewhere in between because it's not curly or straight. He has been bleaching his hair blonde since he was about...twelve, I think. He is naturally a brunette. A lot of people know him as "the blonde one", because he is the only non-brunette of 1D. His hair is sometimes slightly "up", but when he as on x-factor, it was madami like a mop because it was longer.
Zayn Malik has hair that is also slightly "up" at times. He has dark hair that is sometimes all straight up, sort of like less extreme paully d. But often it is just sort of swept to the front, creating a little pouf. Occasionally zayn has is hair all down without a pouf thing, but not often.
Last but not least, Louis tomlinson! While he was on x-factor, he had a slight "bowl cut" as some may call it. I think Louis straightens his hair, but not sure. Now his light brown locks are kinda pushed to one side. I personally prefer his hair not bowl-cutish.
There you have it, a guide to one direction's lovely hair!!!