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 differ noticeably from juvenile leaves of 'Purpurea'. If 'Atropurpurea' is a wych cultivar, its seed should be central in the samara rather than marginal (see 'Putative specimens' below).