Field mustard is Sinapis arvensis
Turnip rape is Brassica rapa, often grown as trap crop to protect oil seed rape (Brassica napus) from insect pests.
Yep. There is a whole range of rapistrum species, turnip-weed and ------- cabbage are just two of them. Last year I thought I had seen a field of OSR near me, which was very unlikely; when I drove to the field I found it was weed - r . rugosum a flowering mustard - ------- cabbage/common giant mustard/turnip-weed. There are all Brassicaceae.