Plants
Stems, Roots and Transport
(12.3-12.5)
Function of Stems…
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Connect vascular tissue in leaves to vascular
tissue in roots
Transports water and dissolved nutrients
Raise and support the leaves and
reproductive organs
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Raising leaves maximizes exposure to sunlight
Raising reproductive organs places them in the
ideal position for pollination
Storage- modified stems in cacti can store
large volumes of water
Structure
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Woody – contain wood and are relatively
hard, have bark, and do not usually carry out
photosynthesis.
Herbaceous- do not contain wood and are
relatively pliable, carry out photosynthesis,
and have a thin epidermis.
Monocots do not produce woody stems
All gymnosperms are woody
Herbaceous…
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The vascular tissue of herbaceous stems is
arranged in distinct vascular bundles in
ground tissue.
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A vascular bundle is a long, continuous strand
of vascular tissue that consists of xylem and
phloem.

In monocots, the vascular bundles are found
throughout the ground tissue of the stem. In
eudicots, the vascular bundles form a ring.
Woody Stems…
 Grow

thick because of vascular cambium
Vascular cambium is a layer of
meristematic cells in the vascular tissue that
divide to form new xylem and phloem cells.
 So
what we call “wood” is actually many
layers of xylem tissue
 Heart wood- old xylem that gets filled with
resin and no longer transports water.
Supports the tree
Bark…(protection-herbivores and water
loss)
 Bark
consists of all the tissues found
outside the vascular cambium. It includes
phloem, cork cambium, and cork.
 The phloem transports sugars made in the
leaves throughout the plant.
 The cork cambium is a layer of
meristematic tissue that produces cork,
the tough, outer layer of the tree that
prevents water loss from the stem.
Growth Rings…
 In
temperate regions growth happens
during spring and summer
 In spring growth is fast and light coloured
wood is produced
 In the summer growth is slower and dark
coloured wood is produced
Cell types
 Xylem
cells are thick walled and dead at
maturity.

rich in lignin, a carbohydrate that makes
the cells very strong.
 Phloem
cells are living at maturity and
contain cytoplasm.
 Both phloem and xylem cells may be
stacked to form long, continuous tubes.
Xylem…
 tracheid
an elongated, tapered xylem
cell with thick cell walls containing small
pits; tracheids overlap one another at the
ends to form continuous tubes from root
to shoot
 vessel element a shorter, blunt-ended
xylem cell with thick cell walls containing
small pits; vessel elements are stacked
end to end to form vessel tubes that run
from root to shoot
Phloem…
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Three types of phloem cells are found in vascular
plants: sieve cells, sieve tube elements, and
companion cells.
Sieve cells have narrow pores in all their cell walls
and contain all the organelles found in most cells,
including a nucleus.
Sieve tube elements have cytoplasm but lack
many cell organelles, including a nucleus. The end
walls of these cells are called sieve plates, which
are cell walls with perforations to allow sugar
solutions to pass to the neighbouring phloem cells.
Companion cell, which is always associated with a
sieve tube element. It has a nucleus and all the
other organelles that the sieve tube element lacks.
The sieve tube elements and their associated
companion cells form long conducting tubes
Cell Specialization…
 Not
all hold a plant upright
 Underground

Tubers, Rhizomes, Corms
 Above
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
modified include
ground modified stems
Stolons grow along the soil instead of upright
Vines
Human Uses…
What do roots do???
Function…
 Anchor
 Keep
upright
 Absorb water and nutrients
 Some roots store water and carbohydrates
for the plant
Types…
 Taproot-
a root system composed of a
large, thick root; can have smaller lateral
roots
 Lateral root- a smaller root that branches
from a larger root
 Fibrous root- a root system made up of
many small, branching roots

Both taproots and lateral roots are covered
with root hairs. A root hair is a microscopic
hair-like outgrowth from an epidermal cell.
Structure…
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Tip of root contains root cap and meristem
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Roots hairs  above the root tip ( S.A)
The root cortex is a region of parenchyma cells
beneath the epidermis.
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Root cap-slippery substance
Meristem- produces new cells for growth
The root cortex store carbohydrates and transport
water from the epidermis to the xylem.
Endodermis is the innermost layer of root cortex
are wrapped with a wax-like substance, forming a
continuous barrier called the Casparian strip
Vascular cylinder…
 Tissue
comprised of xylem and phloem.
 Central part off root
 Eudicots- X shapes vascular cylinder
 Monocots- parenchyma at center
Monocots vs. Eudicots
Root specialization…
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Mutualistic relationships-ex.
With micorrhizae(expand
roots system and perform
external digestion) and
nitrogen fixers
Parasitic- Strangler fig- seeds
are deposited on a host tree
by an animal, the roots grow
downward and strangle the
host tree
Tuberous rootscarbohydrate storage(e.g.
carrots)
Human Root Uses….
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Food- carrots, parsnips, turnips, beets, potato
Beverages-root beer from the sassafras root
Dyes- red(beets or madder), brown
(dandelion)
Pesticides- from rotenone
Medicine- ipecac(induce vomiting), kava
kava (reduce anxiety), valerian (sleep aid)
Erosion Control-forms mat that holds upper soil
layers together
Overall…
Monocots
Eudicots
Embryo with single
cotyledon
Embryo with two cotyledons
Pollen with single furrow or
pore
Pollen with three furrows or
pores
Flower parts in multiples of
three
Flower parts in multiples of
four or five
Major leaf veins parallel
Major leaf veins branched
Stem vascular bundles
scattered
Stem vascular bundles in a
ring
Roots are adventitious
Roots develop from radicle
 Adventitious
root- a root that develops
from somewhere other than the root
apical meristem
 Cotyledon- A cotyledon is a significant
part of the embryo within the seed of a
plant. Upon germination, the cotyledon
may become the embryonic first leaves of
a seedling.
 Radicle – part of root meristem