Lecture 7: Famine and Slavery; structures and functions of stems Flashcards
What type of division do lateral roots do, and from where?
from the percycle; perclinal division occurs; that is division that is parallel to the meristem
Where are all the tissues of stems derived from?
the shoot apical meristem
What does the shoot apical meristem look like?
- a dome or cone at top of plant
- region of rapidly dividing cells
true or false; stems do have zones?
false, they do not
Are the cells further from the peripheral zone more mature?
yes;
Where does the main cell division occur?
the peripheral zone
L1 how doe sit divide?
anticlinal manner
How does L2 divide?
either anti or periclinal
Where do leaves begin?
leaf buttresses
Where is vasculature formed?
from the procambium
- this differentiated as the lead matures
What are the 3 basic types of stem structure
once differentiated
- ) a continuous cylinder eg. magnolia
- ) a discontinuous cylinder (vascular bundles) eg. bean
- ) in bundles scattered throughout ground tissue (monocots) eg. maize
What has continuous cylinders?
magnolids, conifers, eudicots
What do monocots stem structure look like?
vascular bundles (scattered)
true or false; gas exchange can occur in stems
true
What are stems made up of?
Cortex (outer region)
Pith (inner region)
- contain parenchyma, usually with chloroplasts
- intercellular air spaces
-periphery often contains collenchyma
- may contain starch, crystals, glands, laticifers (latex exuding),
- sclereids may be present
What do laticifers produce?
- latex; an emulsion that hardens in air
What are the functions of stems (6)?
- ) production and elevation
- ) Long- distance transport
- ) storage
- ) perennating organs
- ) Dispersion
- ) symbiosis
Describe production and elevation
- applies to leaves, flowers and fruit
- for light capture
- advertising to insects and birds
Describe long distance transport
- long distance transport of water, minerals, photosynthates, nutrients, signals
What happens when a caterpillar wounds a plant( a type of plant?)
wounding sends signals to the plant via signal transduction pathway (as the saliva of the caterpillar stimulates it); the phloem will release volatile attractants to the atmosphere which will signal to a parasitoid wasp to lay their eggs in the caterpillar.
What does it mean by stem storage
- short term (annuals)
- long term (perennials)
What does it mean by perennating organs
- eg. rhizome, tubers, corms, bulbs
- are usually modified vegetative parts of the body (can survive for more than one year)
what does it mean by dispersion function
eg. water plants, stems break apart, carried by water currents
What does it mean by symbiosis
eg. cow wheat and ants
- seeds develop to resemble ants’ cocoons; carried to ants nest
- sweet liquid is released from the underside of the leaf; and ants feed
