Download Trees

Sustainable Resources
11/12
Forestry Unit
Introduction to Trees
Structure and Function of Plants
Botany

Botany: is the science of plants
Plants have the following
characteristics:



1. cell wall
2. photosynthesize (breath in CO2,
breathe out O2, make their own food –
sugar)
6CO2 + 6 H2O + Energy  6O2 + C6H12O6
Introduction to Trees
Trees: are perennial woody plants with apical
dominance.
Apical dominance:
a single main stem
(trunk) that is
dominant over
all other stems.
Trees are Vascular
Vascular:

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vascular tissue is complex, formed of more than one
type of cell. The primary components of vascular
tissue are the xylem and phloem. These two tissues
transport fluid and nutrients internally.
Vascular plants tend to be tall
Types include:
a) cone bearing (gymnosperms = evergreens)
b) flower bearing (angiosperms)
Seed-Bearing Plants
1.
Gymnosperms:
conifers or
cone-bearing
evergreens.
2. Angiosperms: Flowering plants,
enclosed seeds.
Trees
1.

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Conifers:
Are cone-bearing woody trees with vascular
tissue.
Evergreen plants with needle-like leaves.
Dominate the boreal forest making them the
largest carbon sink (a natural reservoir for
the storage of carbon).
Examples of Conifers
A: Pine
Trees
B: Cedar
C: Douglas Fir
D: Hemlock
2. Deciduous trees:


‘falling off or tending to fall off’; these trees
have true leaves that fall off during the colder
and shorter days of the year
Trees lose their leaves to conserve water and
prevent against insect damage.
Examples of Deciduous Trees
A: Maple tree
B: Fruit Trees
C: Alder Trees
D: Birch Tree
E: Willow Tree
Plant Parts
1.
2.
3.
4.
5.
6.
Vascular tissues
Leaves
Stems
Roots
Flowers
Cones
Major Organs of Plants
Flower
Leaves
Fruit/Seed
Stem
roots
1. Vascular Tissue

Leaves, flowers, stems and roots are all
interconnected with a phloem-xylem network.
 Xylem: mainly water and nutrients from
roots.
 “Xy” to the sky
 Phloem” mainly sugar and water from
leaves
Xylem and Phloem
2. Leaves

Purpose: where photosynthesis occurs
(actually inside little, green organelles
called chloroplasts ).

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Cuticle (waxy layer): keeps water in so leaf
doesn’t dry out.
Epidermis: protection and strength
Guard cells = Stomata: air exchange and
control of water loss (“doors” that open when
there is lots of water, close when not).
Palisade Layer: contains chloroplasts to do
photosynthesis
Spongy Layer: also contains chloroplasts;
 Loose packing of mesophyll (middle) cells
facilitates gas exchange
Conifer Leaves

The leaves of many conifers
are long, thin and
have a needle-like
appearance.
Some have flat,
triangular scale-like
leaves.
3. Stems
Functions:

phloem

xylem

1. support leaves
2. movement of materials*
phloem

3. gas exchange and some photosynthesis (green
stems)
*Water moves up stems because of
“transpiration”.

Transpiration: water loss from the plant
through the stomata.

Water molecules are held together by a
cohesive force known as hydrogen bonding.
This is an attractive force that holds water
molecules close together, thus when
transpiration occurs water is pulled up the
stem.
Fact!
Giant redwoods have
been measured around
the trunk and they actually
have a smaller diameter on
hot summer days when
lots of water is drawn up.

Types of Stems:
A. “Herbaceous” (soft and green):
i) Monocot: bundles of xylem and phloem are
scattered throughout the stem.

No vascular cambium (cambium layer of
cells that produce vascular tissues), therefore
diameter is fixed (stem is long and thin)
Monocot
Epidermis
Cuticle (waxy):
prevent water
loss
Cortex: some
photosynthesis
Pith: food storage
Vascular bundle
xylem
phloem
ii) Dicot: vascular bundles arranged in a circle
Epidermis
Cuticle (waxy):
prevent water
loss
Cortex: some
photosynthesis
Pith: food storage
xylem
Vascular bundle
Vascular cambium:
reproduces X & P tissue
phloem
B. “Woody Dicot” (hard, long-lived) i.e. trees.
Ray: transport system
between phloem and xylem
Vascular cambium:
from bark
meristematic =
produces X & P tissue
pith
Sapwood : outer (living)
wood = xylem
Heartwood : inner (dead)
Inner bark = phloem
Outer bark = cork (dead):
contains suberin, waterproof
Functions of Woody Dicot Stuctures


Vascular Cambium: meristematic tissue, here
new xylem and phloem are produced.
Sapwood:
The wood that is formed first. Sapwood is the
younger, outermost wood; in the growing tree
it is living wood, and its principal functions are
to conduct water from the roots to the leaves
(xylem).
Functions of Woody Dicot Stuctures

Heartwood: Dead wood located in the center
of the tree.

Here it is the
darker wood.
Functions of Woody Dicot Stuctures

Inner Bark: part of the periderm (epidermal
meristem) consists of phloem.

Outer Bark: Part of the outer most periderm,
dead waterproof bark.

Pith: center of the stem, trunk or branch.
4. Roots

Functions:
Support the plant and anchor it in the
soil
 Uptake of nutrients and water
 Storage of food

5. Flowers

part of plant which is specialized for
sexual reproduction.
6. Cones

Reproductive structure in a conifer.
Assignment /30 marks

Create a vocabulary list for all of the words
that you have learned during this lesson.
Lots of these words are from the
Greenhouse Unit, put a star beside words
that appear in both the Greenhouse Unit
and the Forestry Unit. You will have a
Vocabulary Test in a few days. In order to
write the vocabulary test you must do a
vocabulary list separate than the notes. I
will be looking for both. 