Abstract The mature seed of Amaranthus hypochondriacus L. consists of a peripheric embryo surrounding the nutritive tissue which is the perisperm. Endosperm remnants are close to the root tip. Cytochemical analysis revealed that the embryo and endosperm cells had a quite homogenous internal organization, with protein bodies embedded in a lipid matrix. The embryo, however, appears variable in tissue organisation, due to the differentiation of the three primary meristematic tissues: the procambium appears as a single bundle in the embryonic axis or as small bundles throughout the cotyledons length, these provascular cells are small and elongated and with fewer reserves and more cellular organelles than the large protoderm and ground meristem cells. These latter cells have more protein bodies, and they show a higher number of larger globoid crystal inclusions than the others. The perisperm is a starchy tissue, and its cells have thin walls and are full of angular starch grains.