Threshing Rape. Women threshing rape with flails. The seed is small and scatters easily as the seed pods split open, so it was threshed on sheets in the field. Brassica napus, a member of the cabbage family and closely related to mustard is grown as a forage crop and for the oil contained in its seed which is used for cooking and now for producing fuel for vehicles. Aquatint from 'The Costume of Yorkshire' by George Walker (Leeds, 1814).