E.pinnatum colchicum x E.grandiflorum.
The darkest flowered of these hybrids that I have grown, although only slightly more so than 'Cupreum'. Raised by A.Donckelaar and named in 1849.
It seems to have larger flowers than 'Cupreum', and to hold the flower clusters among more of the previous seasons leaves (but this might be a matter of cultivation technique).
This shows the two plants together - 'Versicolor' on the left and 'Cupreum' on the right.