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The sheath surrounding the radicle in monocotyledons.



a calyptrate sheath that surrounds the primary root, enclosed in the seed of a plant. It performs a protective function. The coleorhiza is characteristic of cereal grains; it is also present in eucalypti. The growing rootlets rupture the seed (caryopsis), causing it to sprout.

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Homology of the Coleorhiza of Cycad and Grass Embryos
A coleorhiza is found in the embryos of the grass family (Poaceae) but its origin and homology is disputed (Black et al.
by stating: "The coleoptile and coleorhiza are not considered to be parts generated by the eventual shoot and root meristems.