Transcript Plant Structure and Growth - Volunteer State Community College

PLANT STRUCTURE & GROWTH
Nancy G. Morris
Volunteer State Community College
Campbell, 5th edition, Chapter 35
Plant Tissues
• I. Meristematic Tissue
• II. Dermal, Surface, or Protective
• III. Ground or Fundamental
I. Meristematic Tissue
• A. Apical Meristems
• Primary growing tips of shoots & stems
• B. Lateral Meristems
• Produces lateral growth; increase in girth
•
1. Vascular Cambium
•
•
Between primary xylem & phloem
2. Cork Cambium
•
Between bark and phloem
II. Dermal, Surface, or Protective
•
A. Roots
–
–
•
root hairs for adsorption
no waxy covering
B. Stems
–
•
cork, cork cambium
C. Leaves
–
–
–
–
trichomes (multicellular leaf hairs)
waxy cuticle on epidermis
stoma on lower dermis
Special xerophytic adaptations
III. Ground or Fundamental
• A. Parenchyma
•
1. Storage Parenchyma
•
2. Chloroenchyma
• B. Collenchyma
• C. Sclerenchyma
•
•
1. Fibers
2. Sclerids
• D. Vascular Tissues
•
1. Xylem
•
•
•
a. tracheids
b. xylem vessels
2. Phloem
III. Ground or Fundamental
• A. Paraenchyma – Figure 35.11
•
•
•
•
•
•
unspecialized
living
primary cell wall thin & flexible
capable of dividing
metabolic synthesis
storage of starch in plastids
• Chlorenchyma – specialized parenchyma
•
photosynthetic
Paramechyma
III. Ground or Fundamental
• B. Collenchyma –
•
•
•
•
primary cell walls thickened at corners
grouped in strands or cylinders to support
living cells which elongate as plant grows
Figure 35.11
Collenchyma
III. Ground or Fundamental
• C. Sclerenchyma – Figure 35.11
•
•
•
•
•
•
•
dead cells
rigid, thick secondary cell walls of lignin
support for non-growing parts of the plant
fibers –
long, slender, tapered cells in bundles
sclereids – (pears: stone cells)
shorter, irregularly shaped cells
Fiber cells (Bundle cap)
Sclerids or Stone Cells
III. Ground or Fundamental
• D. Vascular Tissues
• 1. Xylem: water-conducting cells
secondary cell walls laid down in spiral/ ring
patterns (which allow stretching) growing parts
•
a. Tracheids – long, thin, tapered cells
with lignin walls and bordered pits
» Water flows from cell to cell through pits
» Also function in support
•
b. Xylem vessel – wider, shorter, thinnerwalled, less tapered (Figure 35.9)
» Aligned end to end to make an element
» Hollow tubes
Xylem
•
•
•
•
conducts water
tracheids evolved first
found in soft woods (balsam, pine)
hard woods have both tracheids &
xylem vessels
• thick walls
• dead at maturity
Pressure flow in a
sieve tube
Roles of
cohesion &
adhesion in
the ascent of
xylem sap
III. Ground or Fundamental
• D. Vascular Tissues – Figure 35.9
• 1. Phloem – food-conducting cells
•
•
•
•
•
•
•
living
thin-watery cytoplasm
sieve-tube members transport sucrose
sieve plate -perforated end wall
callose slime plugs prevent leakage
companion cells provide nuclear control
Phloem
•
•
•
•
alive at maturity
non-nucleated
nuclear control by Companion Cells
sieve-tube members are the sugartransporting cells
• possess sieve plates between adjacent cells
• slime plugs of callose prevent leaking when
damaged
35.9 Food-conducting cells of the phloem
Vessel Elements
Anatomy of
an
Angiosperm
The Angiosperm Body
Roots & shoots are adaptations to living on land!
• Roots functions:
– 1) anchor the plant on land
– 2) absorb & conduct water & minerals
– 3) store food (tap root)
• Root types:
– 1) tap root – carrots, turnips, sweet potatoes
– 2) fibrous root – primarily in monocots
• Root features:
– 1) root hairs – increase surface area
– 2) mycorrhizae – symbiotic root fungus
– 3) adventitious roots – above ground –prop roots
Root Structure
(Figure 35.14 )
Root tip
Roots hairs
Lateral Root
Dicot Root
Monocot and Dicot Root Comparison
Casparian Strip
Shoot System: vegetative & floral shoots
• Stem morphology:
–
–
–
–
1) nodes – where leaves are attached to stems
2) internodes – space between leaves
3) axillary buds – bud in leaf axil
4) terminal buds – bud on shoot tip
• Stem modifications:
– 1) stolons (strawberry runners)
– 2) rhizomes (horizontal underground stems, irises)
– 3) bulbs (vertical, underground shoots with leaf bases
modified for food storage,onions)
– 4) tubers (potatoes- swollen ends of rhizomes)
– Figure 35.6
Iris rhizomes
Figure 35.4
Stem
Morphology
Stem Anatomy
Stem Anatomy
Production of Secondary Vascular Tissue
Anatomy of
stem:
Secondary
Growth
All
wrapped
up!
Shoot System: vegetative & floral shoots
• Leaf functions:
• Absorption of light energy for photosynthesis
–
–
–
–
–
Other modifications:
1) support
2) protection
3) storage
4) attract pollinators
• Leaf modifications: (Figure 35.8)
–
–
–
–
1) tendrils – cling for support
2) spines – protection
3) succulents – storage of water
4) color – attraction of pollinators
Figure 35.20 Anatomy of a Leaf
Cross section of a mesophytic leaf
Gas Exchange through the stoma:
Transpiration
Simple vs. Compound
Comparison of Monocots & Dicots
Uptake of
nutrients
Angiosperms produce
•Flowers
•Fruits
•Seeds
Anatomy of a Flower
Anatomy
of a
Seed
Germination:
Hypogean &
Epigean
Plasmodesmata