bundle sheath extension A portion of ground tissue (PO:0025059) which forms a strip along the leaf veins and extending from the bundle sheath (PO:0006023) to the epidermis. It may be present on one or both sides of the vein and may consist of parenchyma or sclerenchyma. plant_anatomy extensi&#243n de la vaina vascular (Spanish, exact) 維管束鞘延長部 (Japanese, exact) PO:0006022 portion of ground tissue