The word endoderm means two different things in embryology and botanics.
Embryology: the endoderm or endoblast is the internal embryonic leaf which forms the digestive tract (except for the mouth and rectum), the digestive glands and the respiratory tract.
Botanical: the endoderm is the innermost layer of the bark of roots. It is a layer of cylindrical cells that lie between the bark and the central cylinder where the vessels that transport sap are found.
The endoderm is a selective barrier that controls movement of substances absorbed from the earth.
This transverse section of a root shows the different anatomical structures of the root. In botanical terms, the endoderm (4th line from the top), separates the cortex of the bark from the central cylinder. © Beauchamp's Tenth Horse CC by-nc-nd 2.0