• Question: What causes four leaf clovers?

    Asked by anon-358211 on 29 Mar 2023.
    • Photo: Sam Mugford

      Sam Mugford answered on 29 Mar 2023: last edited 29 Mar 2023 8:36 pm

      It seems that the science is not settled on this. There are two main ideas, it might be a genetic mutation, or it might be a response to the environment. If it was a mutation you would expect every leaf on the plant to have 4 leaflets (the 3 leaves of a clover are actually a single leaf made up of 3 – or occasionally 4- leaflets), but usually it is only found on a single leaf, while the others on the plant have 3 leaflets. So it seems more likely that something has gone wrong in the leaves that develop 4 leaflets, it might be stress from an injury or another environmental stress that causes the unusual development of a 4th leaflet.

      But its also possible that it might be a genetic mutation, but one that is only present in part of the plant and not the other leaves. These are called somatic mutations.

      Its a question that needs more experiments to get a full answer to. I can think of a few experiments that we could do to find out. For example we could sequence all the DNA from a 4-leaved clover and from the other 3-leaved leaves on the same plant and look for differences. Or we could expose clover plants to stress to see if it causes plants to grow extra leaflets.

    • Photo: Rosa Sanchez-Lucas

      Rosa Sanchez-Lucas answered on 4 Apr 2023:

      Well, there is a specific specie of Oxalis that always produces 4 leaflets clover, it is called Oxalis deppei or Oxalis tetraphylla. The rest of Oxalis can produce 3 leaflets with some mutations as Sam cited to produce an additional one. Also, we need to discriminate between Oxalis, Trifolium, Medicago and Marsilea genus. All produce 3-4 leaflets (heart shapes, mostly) but they belong to different families.