Rubber (Hevea brasiliensis) is clonally propagated through bud grafting. Rough and corky surface of the graft area on the budded stump was observed as a clear symptom of incompatibility of stock and scion. The anatomical consequences of this is the development of a deflected type of vascular connection between stock and scion and an impeded type of vasculature. Though the morphological expression could be a consequence of structural incompatibility, all structural incompatibilitites are not morphologically expressed. An undulating surface topology of the scion bark is another symptom indicating a differential cambial activity at the tangential plane of mutual contact which may lead to a weak connection of vascular tissue leading to reduced strength at the union part. The impeded vascular tissue may lead to a reduced translocation of metabolities from scion to stock and changes in carbohydrate level and starch distribution in scion tissue, as reported in other crops. Dissimilarities of the graft partners for growth potential may be one of the factors influencing incompatibility.