Herbarium specimens of 'Atropurpurea' (see 'External links') do not appear to differ from juvenile leaves of 'Purpurea'. A wych cultivar, if such 'Atropurpurea' is, would have its seed central, not marginal, in the samara (see 'Putative specimens' below).
The herbarium samples of 'Atropurpurea' do not show significant differences from juvenile leaves of 'Purpurea'. If 'Atropurpurea' is a wych cultivar, its seed should be centrally located in the samara rather than at the edge (see 'Putative specimens' below).