Weed Biology and Identification-202 Target students: M.Sc. Students in Weed Science Lecture: Dr....
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Transcript of Weed Biology and Identification-202 Target students: M.Sc. Students in Weed Science Lecture: Dr....
Weed Biology and Identification-202
Target students: M.Sc. Students in Weed Science
Lecture:
Dr. Majid AghaAlikhani (Ph.D.)
Academic position :
Associate Prof. of Tarbiat Modares [email protected]
1
Basic Parts of the Plant
• Roots• Stems• Leaves• Flower
Sh
oot
syste
mR
oot
syste
m
Taproot
Lateral roots
Sh
oot
syste
mR
oot
syste
m
Taproot
Lateral roots
Leaves
Stem
Sh
oot
syste
mR
oot
syste
m
Taproot
Lateral roots
BranchLeaves
Stem
Sh
oot
syste
mR
oot
syste
m
Taproot
Lateral roots
Apical bud
BranchLeaves
Stem
Sh
oot
syste
mR
oot
syste
mLateral bud
Taproot
Lateral roots
Apical bud
Branch
Node
Internode
Leaves
Lateral bud
Stem
Node
Sh
oot
syste
mR
oot
syste
m
Roots
• 1. Anchor Plant• 2. Absorb water and minerals• 3. Translocate water and
minerals to stem• 4. Store Food
•Root
Structure
Anchorage and support
Storage
Stems
• 1. Translocate water, minerals and food to the leaves
• 2. Support the leaves and display them to light
• 3. Store Food
Woody Dicot Stem
Morphology
Transport and support.
Cactus stems store water, photosynthesize.
Stolons produce new individuals at nodes above ground.
Rhizomes produce new individuals at nodes below ground.
Tubers store carbohydrates.
Thorns provide protection.
Leaves
• 1. Make food through photosynthesis
• 2. Provide site of gas exchange• 3. Store food
Transport of water, sugar, and nutrients through vascular tissue
CO2
Sunlight
Water
Nutrients(such as N, P, K)
Shoot
syst
em
Root
syste
m
•Make food through photosynthesis
Vascular tissue
(b) Close-up of root tip
Ground tissue
Epidermal tissue
Apical mersitem
Sloughed-off root cap cells
Root cap
Root hair
Zon
e o
fC
ellu
lar
Matu
rati
on
Zon
e o
fC
ellu
lar
Elo
ng
ati
on
Zon
e o
fC
ellu
lar
Div
isio
nLateral root
(a) Longitudinal section of root segment
mucilage
Primary Growth
Flowers
• 1. Contain organs for specialized sexual production
• 2. Produce seeds and fruit
Different type of Roots
• A. Tap Root–Continuation of the primary root–Ideal for anchorage–Penetration is greater for water–Storage area for food made by
photosynthesis
ARE YOU PAYING ATTENTION?
• THERE JUST MAY BE A QUIZ!!!
Different type of Roots
• B. Fibrous Roots–Many finely branched secondary
roots–Shallow roots cover a large area
•More effective absorption of water and minerals
•Roots hold the soil to prevent erosion
Different type of Roots
• C. Aerial roots–Clinging air roots
•Short roots that grow horizontally from the stems
•Roots that fasten the plant to a support
–Absorptive air roots
Different type of Roots
• Adventitious Roots–Develop in places other than
nodes–Can form on cuttings and
rhizomes
Roots
• Root hairs: –Tiny one celled hair like extensions
of the epidermal cells located near the tips of the roots where vascular tissues have formed.
–Increase surface area–Absorb water and minerals from soil
Absorbing water and nutrients
Specialized Stems
• A. Corm (gladiolus, crocus)– underground–Solid, fleshy, scale covered
WAKE UP!!!!!!!!!!!!
• DON’T FALL ASLEEP• PAY ATTENTION!• THIS MEANS YOU!!!
Specialized Stems
• B. Bulb (tulips, lillies, onions)–Layers of fleshy scales that
overlap each other–Underground stem
Specialized Stems
• C. Tuber (potato, caladium)–Food storage area–Short, thick underground stem
Specialized Stems
• D. Crown (African Violets, fern)–Closely grouped stems or
plantlets–Just above ground or just below
Specialized Stems
• E. Spurs (pear and apple trees)–Short sems found on woody
plant limbs adapted for increased production of fruits
Specialized Stems
• F. Rhizomes (iris, lily of the valley)–Underground stems that produce
roots on the lower surface and extend leaves and flower shoots above the ground
Specialized Stems
• G. Stolon (Strawberry, airplane plant)–Stem that grows horizontally
above the soil surface
Principal Tissues of the Leaf
• Epidermis–Cuticle
•Waxy substance covers the leaves and stems
•Waterproof layer that keeps water in plants
Principal Tissues of the Leaf
• Epidermis (cont)–Stomata
•Openings in the epidermis mainly located on underside of leaves
•Exchange of gases
Principal Tissues of the Leaf
• Epidermis (cont)–Guard Cells
•Two cells located on each side of stomata
•Open and closes stomata
Principal Tissues of the Leaf
• Mesophyll layer–Palisade mesophyll
•Primary site of photosynthesis–Spongy mesophyll
•Contains air and chloroplasts•Site of photosynthesis and gas exchange
Principal Tissues of the Leaf
• Veins or vascular bundles–In spongy mesophyll–Phloem tissues conduct food from
photosynthesis to rest of plant–Xylem tissues conduct water and
minerals up to cells in leaves and stems
Parts of the Flower
• Sepals–Outer covering of the flower bud–Protects the stamens and pistills
when flower is in bud stage
Parts of the Flower
• Petals–Brightly colored–Protects stamen and pistills–Attracts pollinating insects
Parts of the Flower
• Stamens–Male Reproductive part–Anther-produces pollen–Filament-supports the anther
Parts of the Flower
• Pistil–Female reproductive part–Ovary
•Enlarged portion at base of pistill•Produces ovules which develop into seeds
–Stigma•Holds the pollen grains
Parts of the Flower
• Style–Connects the stigma with ovary–Supports the stigma so that it can
be pollinated
Complete and Incomplete Flowers
• Complete: have all four main parts–Sepals–Petals–Stamens–Pistils