Plant Structure, Growth & Function

Dermal Tissue
 Outer Covering
 Protection

Vascular Tissue
 “Vessels” in Plant
 Transports Materials

Ground Tissue
 “Body” of Plant
 Photosynthesis, Storage,
Support
Meristems can generate new dermal, vascular and ground
tissue in plants
 Primary Growth accounts for a plant’s lengthwise growth
from root and shoot tips
 Secondary growth accounts for increases in width (girth)
among woody dicots only

Shoot apical meristem

Apical meristems
produce the new
cells that enable a
plant to grow in
length, both above
and below ground,
as well as to branch
Developing
vascular
strand
Axillary bud
meristems

The shoots of some
monocots have
intercalary
meristems at the
base of each
internode, causing
continual
elongation

The root cap is a cone
of cells that protects
the delicate, actively
dividing cells of the
apical meristem
 It replaces the cells of
the root cap that are
scraped away by the soil
and it produces the cells
for primary growth

Runs continuous throughout the plant and transports
materials between roots and shoot
 Xylem tissue transports water and dissolved minerals upwards from
roots into the shoots
 Phloem tissue transports food from the leaves to the roots and to
non-photosynthetic parts of the shoot system
Phloem
Sclerenchyma
(fiber cells)
Xylem
Pith
Epidermis
Ground
tissue
Ground tissue
connecting
pith to cortex
Vascular
bundle
Cortex
1 mm
(a) Cross section of stem with vascular bundles forming
a ring (typical of dicots)
Epidermis
Key
to labels
Dermal
Ground
Vascular
Vascular
bundles
(b) Cross section of stem with scattered vascular bundles
(typical of monocots)
1 mm
Primary growth in stems
Epidermis
Cortex
Shoot tip (shoot
apical meristem
and young leaves)
Primary phloem
Primary xylem
Pith
Lateral meristems:
Axillary bud
meristem
Vascular cambium
Cork cambium
Secondary growth in stems
Periderm
Cork
cambium
Cortex
Root apical
meristems
Primary
phloem
Pith
Primary
xylem
Secondary
xylem
Secondary
phloem
Vascular cambium

Vascular Cambium is a
cylinder of actively
dividing cells located
between the xylem and
phloem. It adds cells on
both sides
 Secondary Xylem towards
the inside of the stem
 Secondary Phloem
towards the outside of the
stem
Cork Cambium is
another lateral meristem
which produces cork
(part of bark)
 Together, the secondary
vascular tissues (formed
by vascular cambium)
and periderm (formed by
cork cambium) makes up
the secondary plant
body

Bark is made of
phloem, cork
cambium and
cork.
 Older phloem is
pushed outward


Annual Growth Rings are xylem tissue formed by the
vascular cambium during one growing season (1 year)
 Environmental conditions during the growing season affect xylem
 Springwood – large and thin-walled cells (cooler, wet climate)
 Summerwood – narrow and thick-walled cells (hotter, dry climate)