Download primary growth.

Seed Plant Structure and Growth
Section 3: Plant Growth and
Development
Preview
• The Plant Embryo
• Meristems
• Primary Growth
• Secondary Growth
Section 3
Seed Plant Structure and Growth
Section 3
The Plant Embryo
• Plants continuously make new cells, which differentiate
and replace or add to existing tissues.
• A seed develops from an ovule and contains a plant
embryo.
Seed Plant Structure and Growth
Section 3
The Plant Embryo, continued
• The plant embryo possesses an embryonic root and
shoot.
• cotyledons, or seed leaves, are attached to the
embryonic shoot.
• In angiosperms (flowering plants), embryos have one or
two cotyledons.
Seed Plant Structure and Growth
The Plant Embryo
Section 3
Seed Plant Structure and Growth
Section 3
The Plant Embryo, continued
• Germination
– a plant embryo growing after a period of dormancy
• Seeds sprout in response to certain changes in
the environment.
– Rising temp
– Increase moisture
• Some seeds must be exposed to cold, fire, or
damage before they can sprout.
Seed Plant Structure and Growth
Section 3
Visual Concept: Germination of a Monocot
Seed Plant Structure and Growth
Meristems
• Plants grow by producing
new cells in regions of
active cell division called
meristems.
• Meristems are made up
of undifferentiated cells
that divide and can
develop into specialized
tissues.
Section 3
Seed Plant Structure and Growth
Section 3
Meristems, continued
• Growth that increases the length or height of a plant is
called primary growth.
– Primary tissues
• Growth that increases the width of stems and roots is
called secondary growth.
– Secondary tissues
Seed Plant Structure and Growth
Visual Concept: Meristem
Section 3
Seed Plant Structure and Growth
Section 3
Primary Growth
• Apical meristems,
– located at the tips of stems and roots
– primary growth through cell division.
• The new cells differentiate into roots, stems, and
leaves.
• Each branch of a stem and root has its own
apical meristem that produces new primary
tissues as the branch grows.
Seed Plant Structure and Growth
Section 3
Visual Concept: Primary Growth in Plants
Seed Plant Structure and Growth
Section 3
Secondary Growth
• Some of the undifferentiated cells that are left behind as
stems and roots lengthen and produce lateral
meristems.
• The two lateral meristems responsible for secondary
growth are called the cork cambium and the vascular
cambium.