In The Garden: What is this?

I have this plant growing in my garden, which has a slight fragrance. Anyone know what it is?

 

Fennel

 

Thanks. I wonder how it came to be there, I've never grown it.

 

Dill has slightly broader leaf segments, 1-2mm broad, not the ½mm broad thread-like segments that Fennel has. Dill is also softer; fennel, by this time of summer, is quite tough, almost wiry (try chewing some!).