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Apical meristem – This top most bud on the plant is the main growing point from
which new leaves are initiated and produced. It is enclosed in the leaf of
the youngest developing leaf. Axillary meristems – These “lateral” buds are present at each node above the soil
surface. They normally remain dormant, but growth can resume from these buds
if the apical meristem is destroyed. Branch roots – These roots develop of off the main root and explore the upper
portions of the soil for water and nutrients. Cotyledons – These seed leaves are present in the embryo before
germination. They are the food source for germination processes and also
support the plant through photosynthesis until the first true leaves are
formed. The cotyledons must be pulled through the soil by the hypocotyl
during the emergence process. Epicotyl - The part of the stem
above the cotyledons. Hypocotyl - The part of the stem below the cotyledons. During germination
and emergence it forms an arch and elongates to pull the cotyledons through
the soil. The arch straightens when the epicotyl senses light at the soil
surface and the cotyledons unfold to intercept sunlight for photosynthesis. Radicle – This embryonic root is present in the seed and grows to form
the root system. The bean radicle develops into a main taproot from which
lateral branches form. True leaves –The leaves that form after the cotyledons have unfolded. The
first true leaves on a bean plant are a pair of unifoliolates (consist of
only one leaflet) opposite each other on the stem. All subsequent leaves are
trifoliolates (three leaflets per leaf) that alternate up the stem with one
leaf per node. |
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