The Citrus can mutate to an Arthurium. Since the flowers and foliage mutate separately, the best chance you have is to plant a bunch of Citrus Reptans and wait until they mature (so that you can see their flowers and the effect of the mutagen). Mutate each plant one time, then move to the next one if you don't get the result you want. Make sure you reserve at least one plant to make more Citrus Reptans seeds in case you don't succeed getting the Arthurium in the first batch.