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Coleoptile – This structure covers the shoot and provides protection as it
moves through the soil during emergence. When the coleoptile senses light it
stops growing and splits allowing the shoot to grow through it. First leaf blade – The blade of the first leaf of corn has a rounded tip. Growing point – This is the point from which new leaf tissue is initiated. In
corn it remains below the soil surface until about 3 to 4 weeks after
emergence. Mesocotyl - This tubular, white, stemlike tissue connects the seed and
the base of the coleoptile. It elongates upon germination elevating the
coleoptile towards the soil surface. It stops elongating when the coleoptile
senses light. The mesocotyl is technically the first internode of the
stem. Nodal roots – These roots, which develop from shoot nodes, form the
secondary root system. After the first few weeks of growth, this root system
captures most of the nutrients and water needed for plant growth. Radicle – This embryonic root is present in the seed and grows to form
the first root of the young plant. It and the seminal roots together make up
the primary root system, which supports the corn plant early in its life. The
primary root system stops growing when about three leaves have been formed. Second leaf blade – This and all subsequent leaves have a pointed tip. Seminal roots – These roots were initiated during seed development and are
already formed in the embryo before the seed germinates. A corn plant has 3
to 4 seminal roots. Together with the radicle they form the primary root
system. |
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