Please enable JavaScript.
Coggle requires JavaScript to display documents.
Tissues & Primary Growth of Stems (5) (Stem Growth &…
Tissues & Primary
Growth of Stems
(5)
Types of
Cells & Tissues
Parenchyma
Most common
Cells
Only primary walls
Remain thin
Tissues
Mass of parenchyma cells
Constitutes soft part of plants
Soft Leaves
Petals
Fruits
Seeds
Collenchyma
Primary cell wall
Thin in some areas
Thickened in other areas
Corners
Important to its:
Function
Existence
Only in shoot tips and petioles
Stretchy
Must be short to be strong
Parenchyma needed for support
Sclerenchyma
Used for strength
Cell walls
Thin Primary
Thick secondary
Almost always lignified
Elastic
Developed from Parenchyma
External Organization
Stem
An Axis
Shoot
Stem
Leaves
Flowers
Flowers
Nodes
Where leaves attatch
Internodes
Space bt Nodes
Leaf Axil
Stem area above where leaf attaches
Axillary Bud
Within Leaf Axil
Miniature shoot
Dormant apical meristem
Several young leaves
Vegetative
Grows into branch
Floral
Grows into flower
Bud Scales
Modified Leaves
Smalll
Corky
Waxy
Terminal Bud
At extreme tip of stem
Internal Organization
EPIDERMIS
Outermost layer
Single layer of living Parenchyma cells
Differs from human epidermis
Thicker
Many layers of dead cells
Cutin
Encrusts outer tangential walls
Fatty substance
Makes wall impermeable to water
Cuticle
More/Less pure layer of cutin
Stoma
Guard cells
Stomatal Pore
CORTEX
Interior to epidermis
SImple
Homogenous
Composed of
Photosynthetic parenchyma
Sometimes collenchyma
VASCULAR TISSUES
Xylem
2 types of conducting cells
Tracheids
Vessel elements
Phloem
2 types of conducting cells
Sieve cells
Sieve tube members
VASCULAR BUNDLES
Xylem & Phloem together
Stem Growth & Differentiation
Apical Meristems
Cells divide by
mitosis
cystokinesis
Subapical Meristems
Right below apical meristem
cells also grow & divide
Produce cells for region below
Protoxylem
First xylem to appear
Metaxylem
has longest time for growth
Vascular Bundle
Exterior cells
protophloem
Cells closest to metaxylem
metaphloem
Protoderm
epidermal cells
early stages of differentiation
Provascular tissues
Young cells of xylem & phloem
Ground meristem
Young cells of pith and cortex
Protect delicate
organs inside
