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Vascular tissue that transports sugars and
amino acids throughout the plant
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The process of moving organic material
through the phloem
◦ Uses energy in the form of active transport to carry
organic material from source (location of synthesis)
to sink (location of use)
◦ Since there is active transport the tissue needs to
be living. Therefore phloem is alive and functional
at maturity.
 However it is hollow to facilitate the movement of
materials
Draw
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
Sieve Tubes (hollow)
Companion cells (house mitochondria and
nucleus which regulate products for both cell
types)
Connected by
Plasmodesmata
(channels)
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Draw


Sieve Tubes (hollow)
Companion cells (house mitochondria and
nucleus which regulate products for both cell
types)
Connected by
Plasmodesmata
(channels)

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Leaves of plants (photosynthesis)
Underground roots and stems - store
carbohydrates
◦ Bulbs, tubers, storage roots
◦ Act as the source but can also be sink
◦ Therefore translocation can occur in all directions
https://www.youtube.com/watch?v=M
xwI63rQubU
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Xylem and phloem lie adjacent to each other
Allows water to move easily
Sucrose typically moves into phloem
Osmotic gradient causes water to move into phloem
Organic materials move from source to sink from
areas of high concentration to areas of low
concentration
◦ Sucrose: transport sugar molecule
◦
◦
◦
◦
Draw
https://www.youtube.com/watch?v=I8ZijaOX9M
1:39 - 4
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The water pressure inside plant cells
Can also be called hydrostatic pressure
Stem
Root
Draw
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
Vascular bundle: Holds the xylem and phloem
Vascular cambium: located between the
xylem and phloem
◦ Made of undifferentiated cells to become either
xylem or phloem
Transpiration
Translocation
Passive: water diffuses into the xylem
and evaporates from the leaves
Active: sucrose and amino acids are
pumped into the phloem
Transports water and minerals
Transports sucrose, amino acids and
hormones
Consists of vessel elements and
tracheids
Consists of sieve tubes and companion
cells
Dead at functional maturity
Alive at functional maturity
Moves water and minerals from the
roots to the shoot (one direction of
travel)
Moves organic molecules from the
source (leaves or storage organ) to the
sink (growing plan structure: fruits,
seeds, roots)