Quiz 3: Stems Flashcards
what are 4 characteristics of stems
- generally above ground
- must have buds (apical and or axillary )
- support for leaves, flowers ect
- conduits of vascular system
differences between vascular arrangement between monocot and dicot
- monocot: distributed through stem
- dicot: ring structure
what is a node? what are 3 different types of leaf distributions
- segment of the stem at which leaves and axillary buds are attached
1. alternate: 1 leaf/ node
2. opposite: 2 leaves / node
3. whorled: 3 or more leaves/ node
what is internode?
segment of stem between 2 nodes
what is petiole
‘stem’ - attaches the leaf blade to the actual stem
apical vs axillary
- apical at end of stem
- axillary where leaf meets the node of the stem
what are 6 factors that influence internode length
- fertility of soil
- season (time of year) - daylength
- vigour
- stress
- competition
- light levels
what is etiolation
- tissue that doesn’t have chlorophyll ( appears white)
apical bud
-bud at tip of stem
apical meristem
-region of actively dividing cells at tip of a growing root or stem
axil
angle between the upper surface of a leaf and the stem to which its attached
axillary bud
bud located at axil at the base of a leaf
axillary bud primordium
immature axillary bud
describe apical dominance
apical bud creates hormones that control growth of plant further down
- if removed = promoted growth further down/ branching
- further down a tree is the less influence the apical bud has ( pyramidal shape)
what is coppicing
- cut plant/ shrub close to ground in fall to get new, more shoots next season
what are 5 external features of stem that can help in plant ID?
- lenticels: small gas exchange opening in cork of a woody stem
- leaf scar: scar left on stem after leaf has fallen
- bud scales: terminal bud scales mark each years growth
- bundle scar: where vascular bundle enter leaf
- pith: spongy, central cylinder of tissue found inside stem
Secondary growth:
a) occurs in which plants
b) describe where occurs in trees and shrubs
a) gymnosperms and dicots, not usually monocots- palm tree exception
b) trees- one or few trunks to support tall leafy growth
shrubs- many woody stems that branch closer to the ground
advantages and disadvantages of woody growth
pros
1. exploitation of niche- reaching for sunlight
2. protection of tissue- vascular system protected from predators
3. support- branching over wide areas
4. longevity- up to 1000s of years
cons
5. costly- energy and time
6. flexibility- brittle susc. to wind damage
what does xylem mean in greek
wood