Lecture 5 - Shoot Structure And Development Flashcards
What is the Shoot
Above ground part of plant
What does the shoot consist of?
Stem and leaves
Stem function
Structural support
Conduction of water and nutrients
Leaf function
Capture light
Photosynthesis
What dues Herbaceous mean
Stems die back to ground
Annuals
Live for one growing season
Biennials
Leaves first growing season, flowers an fruit second season, die
Perennials
Live 3+ years
Woody plants live for:
Persist for several seasons without dieback
Woody plant classifications
Tree, shrub, liana
Tree
Dominant vertical trunk, > 5m tall
Shrub
Multiple branches with near ground origin, <5 m tall
Liana
Large woody vine, climbs other plants
Deciduous
Lose leaves annually
Evergreen
Foliage throughout the year
Name the Stem parts
Nodes, internodes, buds
What are Nodes
Origin of leaves and branches
Where are Internodes located
Region between nodes
What are Buds
Undeveloped stems, leaves, and flowers
Bud types
Terminal buds, axillary (lateral) buds, adventitious buds
Where are Terminal buds
Occur at branch tips
Where are Axillary (lateral) buds
In leaf axils
Where do Adventitious buds develop
Develop at locations other than branch tips or leaf axils
Shoot growth consist of:
Primary and secondary growth
Primary growth in shoot is:
Addition of tissue to the shoot by the shoot apical meristem
Primary growth process is:
Repetitive addition of phytomeres
Phytomeres consist of?
Node, lateral organ, Axillary bud, internode
Lateral organ
Leaf
Shoot growth: axillary bud location
At base of leaf
Shoot growth: internode location
Below the leaf
Shoot apical meristem cells are:
Dome shaped cells at stem tip
Shoot apical meristem functions
- directs daughter cells to differentiation
- Site of pattern formation of leaves
What is the shoot apical meristem?
Region in flowering plants responsible for the growth of new shoots
Shoot apical meristem organization
Tunica-corpus
Tunica location
Outermost layer of cells
How do tunica cells divide?
Anticlinally
Corpus location
Body cells under the tunica
How do corpus cells divide?
Periclinally and anticlinally
Protoderm origin
Outermost tunica layer
Where is the procambium and part of the ground meristem derived from?
Peripheral zone
Where is the rest of the ground meristem derived from?
Pith meristem
Primary meristems (3)
Protoderm, ground meristem, procambium
Protoderm primary tissue
Epidermis
Ground meristem primary tissues
Ground tissues (parenchyma, collenchyma, sclerenchyma)
Procambium primary tissues
Primary Xylem and primary phloem
Leaf primordia is produced in:
Continually produced by:
Describe their initial internode elongation
Produced in precise geometric patterns
They are continually produced by the meristem
Initially have little internode elongation
Phyllotaxy
Precise geometric patterns
What happens as new leaves displace old ones?
Internodal elongation
Leaf primordial processes lead to what?
Repetitive phytomeres
Internode elongation advantages
Captures more sunlight by reducing leaf overlap
Grows taller than competition
Internode elongation disadvantages
Lodging, hollow pith, protoxylem lacuna occurs in monocots
How does stem growth occur?
By cell enlargement in the internal region
What develops in older leaf primordia axils?
Bud primordia
Apical dominance
Terminal bud inhibits lateral bud growth
What happens if the terminal bud is removed?
A lateral bud develops and becomes the terminal bud
What happens as the lateral buds get further from the terminal bud?
They will develop
Dicot stem procambium distribution
Isolated small cylinders, distributed in a regular pattern- eustele
Dicot stem innermost ground tissue is called?
Pith
Dicot stem external ground tissue is called?
Cortex
Dicot stem vascular bundles are called?
Fascicles
Dicot stem ground tissues between the fascicles are called?
Interfasicular regions or pith rays
Dicot stem Xylem is usually in?
Inner portion of the vascular bundle
Dicot stem phloem is usually in?
The outer portion
Dicot stem bundles is usually in?
A single ring
Monocot stem vascular bundle organization
Scattered-atactostele
Atactostele
Scattered vascular bundles
Eustele
Vascular bundles in a ring
Describe a monocot stem
Stem covered in epidermis, with stomata and thick cuticle. The rest is parenchyma with embedded vascular bundles.
Where are monocot small and large vascular bundles?
Smaller vascular bundles in outer stem, larger ones in Center
Do monocot stems have a pith?
No
Monocot stem Xylem location
Inner part of vascular bundle
Monocot stem phloem location
Outer part of vascular bundles
Monocot stem vascular bundles are surrounded by?
Bundle sheath
Monocot stem phloem organization is?
Highly organized
Monocot stem: Large metaxylem vessels and smaller protoxylem is:
Xylem
Monocot stem elongates rapidly which leads to what?
Protoxytem lacuna
Describe the structure of vascular tissue in the stem and leaf.
Individual vascular bundles that run separately through the stem.
Define leaf trace.
A vascular bundle that diverges from the axial bundle in the stem and enters a leaf
Where are leaf traces produced?
At nodes
Each leaf trace equals how many vascular bundles?
One vascular bundle
Dicots: the axial bundle forms how many bundles at what location?
3 bundles at the node
Dicot: What does the central bundle become?
The leaf trace
Dicot: The other 2 bundles unite where? What do they reconstitute?
Unite above the node, reconstitute the axial bundle
Modified stems
Rhizome, stolon, tuber, corm, thorn, cladophyll
Describe rhizome
Underground stem, usually horizontal that has nodes and internodes
Describe stolon. What kind of roots does it produce?
Horizontal stem, produces adventitious roots
Describe tuber.
Develops underground- enlarged, short, fleshy
Describe corm. Starch is usually?
Swollen base of stem enclosed in dry scale-like leaves. Starch is usually accumulated.
Describe thorn.
Short, sharp point
Describe cladophyll. What is it specialized for?
Flattered stem specialized for photosynthesis
