Coleoptile

The coleoptile is a thick tissue that covers the plumule and eventually the growing shoot of a vascular plant. It is specifically present in monocots that do not form hooks in the developing hypocotyl or radicle regions after emerging; it exists to protect and sheath the plumule and later the emerged apical meristem as it erupts vertically from the ground.

The coleoptile grows between the plumule and the cotyledon; this forms an internode between the connection of the cotyledon and the connection of the coleoptile known as the mesocotyl.

During juvenile growth, the coleoptile forms a “bump” on the aboveground plant. Closer to the leaf blades that develop from the apical meristem, the coleoptile appears thinner and translucent, and one can see the linear, parallel lines, similar to that in a standard monocot leaf.