Fasciation is defined as the abnormal flattening of plant organs. I have only seen it on the stems. This occurs when the cells forming new tissue change from the typical cone shape to a line. I remember seeing examples of red maple and sweet potato. The most common plant I have seen fasciation on is serrcia lespedeza. I don’t know how many of those I have seen. Here is a photo of fasciation on wild mullein. I recently found two of these. This one looks a little like an end wrench.