Dimidiate

a dimidiate leaf, which has only one side developed

dimidiate hermaphroditism

[…] it may be dimidiated: for instance, half a rose and half a lis being stuck together, or half a lis and half an eagle.

[…] hybridization in the same vein is the beast shown as supporters to arms granted in 1971, where a unicorn dimidiates a lion rampant.