the middle layer, the "mesocarp" or "sarcocarp"; the inner layer, the "endocarp". Botanists have not applied these terms consistently. Exocarp and endocarp may be restricted to more-or-less single-layered "skins", or may include tissues adjacent to them; thus on one view, the exocarp extends inwards to the layer of vascular bundles ("veins"). The inconsistency in usage has been described as "a source of confusion".

The nature of