Download Plant Tissues

Plant Tissues
Plant structures are composed of 4 main tissues.
They are:
Epidermis – outer layer of cells which protect the
plant from water loss and from fungi and
bacteria
Vascular Tissues – transport water, sugars and
other materials through the plant
Ground Tissues – tissues that the vascular tissue
is embedded in…. usually storage cells
Meristematic – cells that divide
Plant Tissues
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Meristematic- growth
Epidermal- protection
Parenchyma- storage
Sclerenchyma- strengthen and support
http://www.lima.ohioVascular- transportation
state.edu/biology/image
– xylem = water + nutrients s/zeaxs.jpg
– phloem = plant products in solution
Plant Tissues
In Most Plants
• Glucose is produced in the leaves
through photosynthesis.
• The glucose is converted to sucrose
(by dehydration synthesis) for
transportation.
• The sucrose is converted to starch and
stored.
Roots
Roots have many functions.
1. anchor the plant
2. bind soil… stops erosion
3. absorb water and minerals
4. store food (usually as starch)
Root Types
Taproots
• look large and fleshy,
• are mostly found in plants
with two seed-leaves
(dicots),
• grow deep into the
ground to search for food,
• are able to store food,
which is particularly
necessary for perennial
plants during periods of
dormancy.
Fibrous roots
• lie close to the surface of
the soil,
• are mostly found in plants
with one seed-leaf
(monocots)
• collect precipitation before
it sinks deep into the
ground,
• can often be found growing
side by side with taprootsthe two types of roots
combine efforts to
maximize efficiency.
Adventitious roots
• are common in both
dicots and monocots
• develop to help the
plant climb: for
example, ivy
• help develop
modified
underground stems,
such as bulbs
Aerial Roots
modified to absorb water from the air
Aerial roots of an Orchid
Orchids in bloom
Root Hairs
are actually epidermal cells
adapted to absorb water
Root Hairs
* Water enters the cells by Osmosis
* Minerals enter by Active Transport
Regions of the root tip
• Region of Maturation - Most cells
differentiate into various distinctive cell
types.
– Root hairs form.
• Region of Elongation - Cells become
several times their original length.
– Vacuoles merge
• Region of Cell Division - Composed of
apical meristem in the center of the root
tip.
– Most cell division occurs at the edge of
the inverted cup-shaped zone.
• Root Cap - Thimble-shaped mass of
parenchyma cells covering each root tip.
– Protects tissue from damage.
– Function in gravity perception.
The Root Tip
The Function of Root Tissues
• Epidermis – outer layer of cells, provide protection from drying
out, water loss and infection.
• Cortex – area made up of parenchyma cells. Parenchyma
cells are usually storage cells
• Endodermis – regulates materials entering the center of the
root.
• Pericycle –the outermost layer of cells of the stele
• Xylem – transports water
• Phloem – transports sugar
• Stele – Also known as the “Vascular Cylinder”…… made up of
the xylem and phloem
• Pith – tissue located in the center of the stem
• Apical Meristem - (Meristematic Tissue) – tissue that in a
constant state of growth… apical means “located at the tip”
• Meristem accounts for the increase in length of the roots and
stems.
Dicot Root X-section
Monocot root X-section
Dicot root X-section
Most Dicot roots have an “X” of xylem cells in the center of the root.
The Casparian Strip
regulates the movement of water into the root
Stele