"Broadleaf Grassland", could be considered any plants with a leaf that wide growing in nutrient rich soils in (for example) a flood plain or water meadow where grass is greener than a Wimbldon tennis court!
As a generalisation in the UK, I think that the White Butterflies like this habitat (with their caterpillar food plants). There is a possible exception of the Brimstone which might prefer Broadleaf Woodland where it hibernates in ivy clad trees and uses Buckthorn for it's caterpillars.
