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Vascular Tissue -- Xylem and Phloem
Ground Tissue
-thin-walled and capable of photosynthesis when they contain chloroplasts.
-have thicker walls for flexible support (celery strands).
-are hollow, nonliving support cells with secondary walls.
-forms the bulk of the plant.
SCLERENCHYMACOLLENCHYMA
• Thin cell wall
• Storage & photosynthesis
• Uneven cell wall
• Flexible support
• Thick cell wall
• Strength and support
PARENCHYMA
Plant Ground Tissues
Two Kinds of Plant Vascular Tissue• Xylem
• Phloem
- Upward movement.
- Dead at maturity.
- Carries H2O, dissolved nutrients.
- Carries products of photosynthsis.- Up and downward movement.- Alive at maturity
- Vessel Elements- pitted cell wall. Water pipeline
- Tracheids - pitted
-Sieve tube - perforated end walls
- transport sugar
- Companion Cells- swirl cytoplasm to push sugar up or down
Vessels Tracheids
Sie
ve-t
ub
e
Companion cells
Vascular TissueVascular Tissue
• Two types of vascular (transport) tissue:
• Xylem transports water and minerals from roots to leaves and contains two types of conducting cells: tracheids and vessel elements.
• Phloem transports organic nutrients from leaves to roots and has sieve-tube elements with companion cells, sieve plates.
Xylem structureXylem structure
Xylem transports water and minerals from roots to leaves
Contains two types of conducting cells: tracheids and vessel elements.
Wat
er
Roots
Leaves
Tracheids lie along side other tracheids, over-lapping extensively, so that water can flow out of the pits of one cell into an adjacent cell. This allows long range transfer of water and solutes, although (since the cells are dead) the flow has to be passive, pulled by an external force.
Water Flow (passive flow)
The driving force for this flow is hydrostatic pressure, coming partly from root pressure (pushing up wards) but mainly from the suction pressure created by water being evaporated from leaves. Passive water flow in plants is upwards.
Softwoods (conifers) – tracheids only Hardwoods – note the
larger bore of the vessel elements
Vessel element, here with a open end (simple perforation plate).
Tracheids
A perforated (scalariform) perforation plate
In Angiosperms - Vessel elements, idealised
Phloem structurePhloem structure
Transports organic nutrients from leaves to roots
Has sieve-tube elements with companion cells
cells at sieve plates.
Leaves
Roots
Org
anic
nu
trie
nts