Transcript Document

PLANTS
What is a plant?
•Eukaryotic
Multicellular
Autotrophic
Why are plants important?
•Food
•Oxygen
•Materials (building, paper, clothes)
•Aesthetics
•Shelter
•Medicine
Plant Tissues
•Vascular Tissue: interconnected cells that
make tubes for transport
Xylem: move water from the roots to the
leaves
Phloem: move sugar from roots to leaf
buds (Spring) or leaves to roots (Fall)
WATER-CONDUCTING CELLS OF THE XYLEM
Vessel Tracheids
SUGAR-CONDUCTING CELLS OF THE PHLOEM
Sieve-tube members:
longitudinal view
100 m
Pits
Companion cell
Sieve-tube
member
Sieve
plate
Tracheids and vessels
Vessel
element
Vessel elements with
partially perforated
end walls
Nucleus
30 m
15 m
Tracheids
Cytoplasm
Figure. 35.9
Companion
cell
•Storage Tissue: stores food as starch
Collenchyma – crunchy cells –
carrots and potatoes
•Support Tissue: gives strength to
tissues
Sclerenchyma – stick like
Xylem
•Protective Tissue: keep water in and
invaders out
Cork on stems
Epidermis on leaves – makes a
waxy layer called the cuticle
Prickle
Rose “thorns” are prickles  “A rose between two prickles.”
•Photosynthetic Tissue:
Parenchyma/Mesophyll: inside of
leaves
PARENCHYMA CELLS
COLLENCHYMA CELLS
80 m
Cortical parenchyma cells
SCLERENCHYMA CELLS
5 m
Sclereid cells
in pear
25 m
Cell wall
Parenchyma cells
60 m
Collenchyma cells
Fiber cells
Plant Organs
•Roots:
- hold plant in the soil
- absorb water and nutrients
- store food
- reproduction
(a) Prop roots
(d) Buttress roots
(b) Storage roots
(c) “Strangling” aerial
roots
(e) Pneumatophores
•Stems:
- support leaves and reproductive
structures
- can be specialized to store food or
water or reproduction (potato,
strawberry runners, bamboo shoots)
- modified for defense = thorn
Thorn
•Leaves:
- photosynthesis
- can store water (succulent)
- modified for defense = spine
(cactus)
- specialize for reproduction =
flowers
Spine
External Structure of Leaf
Leaves: External Structure
-
Blade
Petiole
Stipule
Axillary Bud
Veins
Internal Structure of Leaf
Leaf Mesophyll
Leaf Stomata
Leaf Modifications
(a)
Tendrils. The tendrils by which this
pea plant clings to a support are
modified leaves. After it has “lassoed”
a support, a tendril forms a coil that
brings the plant closer to the support.
Tendrils are typically modified leaves,
but some tendrils are modified stems,
as in grapevines.
(b)
Spines. The spines of cacti, such
as this prickly pear, are actually
leaves, and photosynthesis is
carried out mainly by the fleshy
green stems.
(c)
Storage leaves. Most succulents,
such as this ice plant, have leaves
modified for storing water.
(d)
Bracts. Red parts of the poinsettia
are often mistaken for petals but are
actually modified leaves called bracts
that surround a group of flowers.
Such brightly colored leaves attract
pollinators.
(e)
Reproductive leaves. The leaves
of some succulents, such as Kalanchoe
daigremontiana, produce adventitious
plantlets, which fall off the leaf and
take root in the soil.
Important Structures
Stoma: opening for gas exchange
Guard Cells: regulate size of stoma
Mesophyll: photosynthesis
Cuticle: protective waxy layer
Vascular Bundle: xylem and phloem –
vein of leaf
Types of Plants
•Non-vascular plants: No xylem or phloem –
can only move water and sugar by osmosis and
diffusion – keeps them small
Ex: Bryophytes: Mosses and the their
relatives (Liverworts, Hornworts)
- reproduce using spores – produced in
specialized structures called sporangia
- require water for reproduction – sperm
must swim to the egg
•Vascular Plants: Have xylem and phloem
•Types of Vascular Plants:
Seedless vascular plants: Reproduce
using spores
EX: Ferns – produce spores which
grow in sprorangia on the underside of
the leaf, which is called a Frond
•- spores land on ground and grow
into a separate plant which produces
the eggs and the sperm
- water hits this and allows the
sperm to swim to the egg and the
zygote grows into a new fern
•Other Types: Horsetails, Ground Pine
•Seed Plants: Produce specialized
structures (Cones or Flowers) that make
egg cells in an ovary and sperm cells
which are housed inside of pollen grains
- pollen is transferred to the cone or
flower by a pollinator (insects, birds,
bats) to make a new plant and a food
source which is protected inside of a seed
and the cone or the developing fruit
Types of Seed Plants
•Gymnosperms: “naked” seeds – seeds only
have a seed coat and are not protected by a
fruit
Ex: Conifers: cone bearing trees
• - produce two types of cones:
Male cones (make pollen) – very small
Female cones (make eggs) – egg is housed
in the scales of the cone
•pollen is blown by the wind from the male
cone to the female cone and fertilizes the egg
– cone scales close and protect the developing
seed – sperm and egg fuse to make the
embryo and other unfertilized eggs divide to
make a food source in the seed – after several
years the scale opens and releases the seeds –
some conifers require the heat and smoke
from fire to cause the cones to open and
release the seeds
•Angiosperms: “combined” seeds –
seeds that develop from flowers and
have a protective coating around the
seeds that is the mature ovary of the
plant  fruit
- Flowering Plants
Typical Flower Structure and Reproductive Cycle
•Reproduction: Ovary produces egg cells,
anthers produce pollen (houses the sperm and
a specialized cell called the tube cell)
- pollen is transferred to the stigma and
germinates releasing the tube cell and the
sperm cell
•Tube cell makes a path for the sperm cells to
the opening of the ovary
•One sperm fertilizes one egg to make the new
plant embryo and the other sperm fertilizes
two other egg cells to make the food source =
double fertilization
•The food source develops into the seed part
that we eat and the embryo develops into the
young plant
•At the same time the wall of the ovary begins
to grow and expand forming the fruit to
attract animals or help spread the seeds
•Types of Fruits:
- Dry fruits: sunflower seeds,
Maple tree helicopters, burrs,
dandelion tufts
- Fleshy fruits: Apples, bananas,
tomatoes, peppers, cucumbers,
avocado, peas, green beans
•Types Of Angiosperms:
Monocots and Eudicots – “cot” refers to
the cotyledon or the “seed leaf” in the
seed – the first leaf/leaves that emerge
from the growing embryo - embryonic
leaves
Characteristic
Seed Structure
Flowers Parts
Leaf Veins
Roots
Vascular Bundles in
Roots
Vascular Bundles in
the Stems
Secondary Growth
Monocots
One “seed leaf” – made of one piece
Eudicots
Two “seed leaves” – made of
two pieces
Characteristic
Monocots
Eudicots
Seed Structure
One “seed leaf” – made of one piece
Two “seed leaves” – made of
two pieces
Flowers Parts
In multiples of 3
In multiples of 4 and 5
Leaf Veins
Roots
Vascular Bundles in
Roots
Vascular Bundles in
the Stems
Secondary Growth
Eudicot Flower: multiples of 4 & 5
•
From:http://www.csdl.tamu.edu/FLORA/tfplab/rep68.jpg
• From:http://www.thes
eedsite.co.uk/brassica
ceae.gif
Monocot Flower: Multiples of 3
•
From: http://www.emc.maricopa.edu/faculty/farabee/biobk/monocot_flower.gif
Characteristic
Monocots
Eudicots
Seed Structure
One “seed leaf” – made of one piece
Two “seed leaves” – made of
two pieces
Flowers Parts
In multiples of 3
In multiples of 4 and 5
Leaf Veins
Parallel
Net pattern
Roots
Fibrous
Tap root
Vascular Bundles in
Roots
Vascular Bundles in
the Stems
Secondary Growth
Eudicot & Monocot Leaf Veination
• Eudicot – net venation
• Monocot – parallel venation
Eudicot & Monocot Roots - External
• Eudicot – tap root
• Monocot – fibrous roots
Characteristic
Monocots
Eudicots
Seed Structure
One “seed leaf” – made of one piece
Two “seed leaves” – made of
two pieces
Flowers Parts
In multiples of 3
In multiples of 4 and 5
Leaf Veins
Parallel
Net pattern
Roots
Fibrous
Tap root
Vascular Bundles in Xylem in a Circle
Roots
Vascular Bundles in
the Stems
Secondary Growth
Xylem in an “X”
Monocot Root Cross Section
•
From: http://www.inclinehs.org/smb/Sungirls/images/monocot_stem.JPG
Characteristic
Monocots
Eudicots
Seed Structure
One “seed leaf” – made of one piece
Two “seed leaves” – made of
two pieces
Flowers Parts
In multiples of 3
In multiples of 4 and 5
Leaf Veins
Parallel
Net pattern
Roots
Fibrous
Tap root
Vascular Bundles in Xylem in a Circle
Roots
Xylem in an “X”
Vascular Bundles in Scattered throughout – look like little
the Stems
faces
Along the outer edge
Secondary Growth
Monocot Stem Vascular Bundles
Xylem
Phleom
Monocot Stem Vascular Bundle
•
From: http://iweb.tntech.edu/mcaprio/stem_dicot_400X_cs_E.jpg
Eudicot Stem Cross Section
•
From: http://plantphys.info/plant_physiology/images/stemcs.jpg
Eudicot Stem Vascular Bundle
Sclerenchyma
Phloem
Xylem
Vascular Cambium
Characteristic
Monocots
Eudicots
Seed Structure
One “seed leaf” – made of one piece
Two “seed leaves” – made of
two pieces
Flowers Parts
In multiples of 3
In multiples of 4 and 5
Leaf Veins
Parallel
Net pattern
Roots
Fibrous
Tap root
Vascular Bundles in Xylem in a Circle
Roots
Xylem in an “X”
Vascular Bundles in Scattered throughout – look like little
the Stems
faces
Along the outer edge
Secondary Growth
Present – forms layers of new
growth each year – makes
rings of xylem tissue  Annual
Rings
Absent
•Life Cycles:
Annuals: live for one year and then die
Biannual: grow for one year but do not
flower – flower the second year and then
die
Perennials: live for more than two years
and up to thousands