Tissues and Primary growth of stems Flashcards
How are flowering plants classified?
Magnoliophyta or Angiosperms
Magnoliophyta are divided into three groups, name them.
Basal angiosperms
Eudicots (dicotelydon- broad leaves)
Monodicots( monodicotyledon-narrow leaves)
What is the primary body?
It is the herbaceous body that is derived from shoot and root apical meristems.
What primary tissues make up the primary body?
Epidermis
pith (central part of stem, starch storage, intercellular gas exchange, transport of substances from vascular bundle to outer stem)
cortex (collenchyma (support), parenchyma (making food) and endodermis (storage), and others
What is the secondary body?
The secondary plant body is derived from meristems other than the apical meristems growth of secondary tissues in the vascular or cork cambia, it results in the development of wood and/or bark.
What are meristemic tissues in plants?
These are dividing tissues that help the plant grow and are restricted to three parts of the plant apical meristem (growing tips of roots and stems), Lateral meristems (cambium
What are the 3 classes that all cells are divided?
Parenchyma, Collenchyma and Sclerenchyma
What are parenchyma cells?
These are cells are thin walls and make up the soft portions of the plant. They remain metabolically active as they mature.
What are the types of parenchyma?
Chlorenchyma , Glandular cells and Transfer cells
What are chlorenchyma?
These cells are speciallised to do photosynthesis
- they have thin transparent walls that allow light to enter
-they contain chloroplasts for capturing sunlight
What kind of cells are pigmented cells?
Pigmented cells are parenchyma as the walls are thin enough to see the pigments.
What are glandular cells?
These are parenchyma with a lot of golgi apparatus and ER
What are Collenchyma?
These are cells that have unevenly thickened walls as it is only at the corners of the cell.
What do Collenchyma cells do?
These are cells that provide plastic strength to the cell allowing them to be flexible.
Where are collenchyma cells present?
- Under the epidermis of the plant
- Supporting the vascular bundle
- cortex
- leaves
What are sclerenchyma?
These have cell walls that are thick with lignin.
What do sclerenchyma do for the plant?
Elasticity allows for the plant to return to their original shape when deformed.
Strength provides the plant with support despite lack of turgor pressure
What are the types of Sclerenchyma?
Conducting and Mechanical
What are two types of mechanical Sclerenchyma?
Fiber and Sclereid
What are Fibers?
- Long and flexible
- Mostly found in areas that need strength to support but need elasticity to bend
What are Sclereids?
- Short and cuboidal
- Has strong walls that make it inflexible and brittle
- Forms hard, impenetrable
- small plasmodesmata remain free of secondary wall (lignin) become narrow pits
What are pit-pairs?
Pit pairs are plasmodesmata that are next to each other in the secondary wall.
What are conducting sclerenchyma?
Transports water
What are examples of conducting sclerenchyma?
Tracheary elements of the xylem (tracheids and vessel elements)
What is a shoot?
This is that part of the plant comprised of stem and leaves
What are nodes?
Part of the plant that the leaves attach to the stems at
What are internodes?
The regions between the nodes.
What is present above the node?
The axillary bud is present right above the node
It is a miniature shoot with a dormant apical meristem.
What is the terminal bud?
This is the active apical meristem present at the top of each stem
What does phyllotaxy mean?
The arrangement of leaves on the stem
Why is phyllotaxy important?
Determines the amount of sunlight a plant will get based on its position.
Prevents shading of leaves
What is Alternate phyllotaxy?
One leaf present at one node
What is Opposite phyllotaxy
Two leaves per node
What is Whorled phyllotaxy
3 or mores leaves per node
What do the buds above leaves turn into?
- Few turn into branches
- Some remain dormant
- Some produce flowers
Why are the apical buds needed?
They take over the role of the terminal bud if it dies or gets damaged
How do the apical buds remain dormant?
The terminal bud releases hormones from the apical meristem that enforces dormancy in the axillary buds
What is the difference between apical bud and auxillary bud?
POSITION!!!
Apical bud is the terminal bud while axillary bud is called the lateral bud.
Both monocot and dicot plants contain an apical bud at the topmost part of the shoot made up of apical meristem.
Only dicots consist of axillary buds, which remain dormant under the influence of the apical bud.
What are stolons?
A creeping horizontal plant stem.
Long and thin internodes allow for dispersal of daughter plants plants along the length.
What can shoots be used for?
Storage
What is a bulb?
A short stem with THICC fleshy leaves
What are corms?
Vertical, THICCC stems that have thin, papery leaves.
What are rhizomes?
Fleshy horizontal stems that spread underground
What are tubers?
Horizontal stems that grow temporarily
How does an axillary bud become an apical meristem?
If the apical meristem dies then it cannot produce any more hormones to keep the auxillary buds dormant so they will activate replacing it.
