The coleoptile, which encloses the young leaves,
emerges as a tapered cylinder. Its color varies
from colorless, pale green to green, 'or pale purple
to purple. The length of the axis between the
coleoptile and the point of union of the root and
culm is called the mesocotyl. The elongation of the
mesocotyl elevates the coleoptile above the ground.
The coleoptile later ruptures at the apex and the
first seedling (primary) leaf emerges. The primary
leaf is green and cylindrical and has no
blade. The second leaf that follows is differentiat- ed into sheath, blade, ligule, and auricles