Transcript Ground tissue

Anatomy, Morphology, & Growth
of Angiosperms – Ch. 5-8
Two plant groups: monocots & dicots
Cells
Muscle cell
Tissues
Muscle tissue
Organs
Heart
Systems
Circulatory
system
The Plant Cell
Fig 7.8
5 Differentiated Plant Cell Categories
1.
2.
3.
4.
5.
Parenchyma
Collenchyma
Schlerenchyma
Water-conducting cells of the xylem
Sugar-conducting cells of the phloem
1. Parenchyma
• thin and flexible cell walls
2. Collenchyma
• Usually grouped in strands to support young parts
of plants without restraining growth
• Flexible, elongate with growing shoots
3. Schlerenchyma
• May be dead at functional maturity – ???
• cell walls left behind as skeleton
4. Water conducting cells of the xylem:
• 2 types: tracheids & vessel elements
Tracheids
• Water flows from cell to cell (laterally) through
pits in cell wall
• Support function
Vessel Elements
• End walls are perforated for free flow of water
• More efficient as water conductors than tracheids
Fig 35.9
5. Sugar-conducting cells of the phloem
Sieve-tube members:
• Lack a nucleus, ribosomes, vacuole
• Cells separated by perforated sieve plates –
allow sugar movement
Fig 35.9
Three main
tissues:
Dermal,
Vascular,
Ground
Fig 35.8
1. Dermal tissue or epidermis
•
•
Root hairs are specialized epidermal extensions
Secretes waxy cuticle of the leaf
2. Ground Tissue
• fills the space between dermal and vascular
tissue systems.
• Diverse functions:
pith
In dicots:
cortex
3. Vascular Tissue
• function in transport between roots &
shoots, and structural support of plant
– Xylem:
– Phloem: Food transported to roots & nonphotosynthetic parts such as the flowers
Growth & Development
http://www.cneccc.edu.hk/subjects/bio/album/Chapter20/PLANT_GROWTH.html
• Development =
Three processes of development:
1. Growth =
2. Cellular differentiation = generation of different
cell types
3. Morphogenesis – creation of body form &
organization.
1. Growth
• Cell division no expansion
Growth
• = due to water uptake in the vacuole
Fig 35.24
Cell division
• Occurs in only in meristems!
Meristems
•
•
=
Two types of meristems:
1. Apical meristem –
2. Lateral meristems – extend lengthwise along the
axis of the stem & roots. Responsible for
growth in girth in older parts of the plant (called
secondary growth). Exist only in perennials
Fig 35.10
Arrangement of Primary Tissues in Roots
1. Epidermis –
2. Stele –
3. Ground tissue – mostly parenchyma cells of the
cortex – area between the stele & epidermis;
stores food & takes up minerals.
• Endodermis – single cell layer between cortex
& stele. Selective barrier for uptake of soil
solution contents into vascular system.
Eudicot/Gymnosperm root cross section
Epidermis
Endodermis
Cortex
Stele
xylem
phloem
Fig 35.13
Primary Growth of Shoots
• Bud = cluster of leaf primordia created by
meristem. No internodes
• Lateral branches arise from axillary buds
Fig 35.15
Primary tissue arrangement of stems
– Ground tissue = pith & cortex
Eudicot/Gymnosperm stem cross section
pith
phloem
cortex
xylem
epidermis
Fig 35.16
Schlerenchyma
cells
Tissue arrangement of leaves
•
3 parts:
1. Upper & lower epidermis – tightly interlocked
cells, secrete waxy cuticle. Contains stomata
flanked by guard cells
2. Vascular tissue –
3. Mesophyll – ground tissue between upper &
lower epidermis
Fig 35.17
Secondary Growth
•
Two lateral meristems:
1. Vascular cambium – produces secondary
xylem (= wood) & phloem
2. Cork cambium – replaces the epidermis with
cork: tough, thick cover for stems, roots.
Secondary growth of stems
• Vascular cambium – layer of cells between
primary xylem & primary phloem. Puts on
successive layers of secondary phloem to outside
& secondary xylem to inside =====> stem widens
• Wood = accumulation of secondary xylem. Dead
at maturity, contains lignin
What is bark?
• “bark” =
• Cork continually sloughs off
Fig 35.18
Fig 35.20
Three types of life cycles:
1. Annual –
2. Biennial – complete life cycle in two years (first
year = vegetative, second year = reproductive).
Some need a cold winter period to initiate
flowering from vegetative state. Ex. carrots
3. Perennial – live year after year, do not die after
reproduction. Examples: trees, shrubs, some
grasses. Causes of death = fire, disease