Chapter 6 - Stems Flashcards
STEMS:
Axillary buds are on the sides of the stem whereas __________ are at the tips/ends
Terminal buds
STEM MONOCOTS:
*Outermost tissue
*Single layer of compact parenchyma
* Covered with waxy cuticle
* Cell walls highly silicified
* Trichomes absent
* Stomata present in low number
* Layer persists for life of plants
Epidermis
STEM MONOCOTS:
Function: protection, conserve water, and gas exchange
Epidermis
STEM MONOCOTS:
*Just below epidermis
*Made of several layers of sclerenchyma
*Chlorenchyna present in some plants
Hypodermis
STEM MONOCOTS:
Function: support, protection, and photosynthesis
Hypodermis
STEM MONOCOTS:
*Below hypodermis
*_______ not differentiated
*Composed of cortex ONLY
*Made of large, loose parenchyma cells
Ground tissue
STEM MONOCOTS:
Function: food storage & support
Ground tissue
STEM MONOCOTS:
Describe vascular tissues/bundles
*Arranged in bundles
*VB are numerous and scattered in ground tissues
*Larger near the middle and smaller near the edge
*VB are conjoint, collateral, and closed
*Lack cambium (closed) - no secondary growth
STEM MONOCOTS:
Vascular element: two large vessels. Typically on the inside of VB
Xylem
STEM MONOCOTS:
Vascular element: only sieve tubes and companion cells. Typically on the outside of VB
Phloem
STEM DICOTS:
Layer of compact parenchyma w/ thick cuticle
Trichomes & stomate present
Herbaceous spp – EPI lasts life of plant
Woody spp – EPI replaced by periderm
Functions: like monocots, trichomes give extra protection
Epidermis
STEM DICOTS:
What are the 4 cortex zones?
~Hypodermis
~Outer cortex
~Inner cortex
~Endodermis
STEM DICOTS:
What is located below the epidermis?
The cortex
STEM DICOTS:
o Thin, compact layer just below epi
o Collenchyma with thick primary walls at the corners
o Chloroplasts usually absent
o Function: mechanical support
Hypodermis (80% sure its the cortex)
STEM DICOTS:
o Loosely packed chlorenchyma cells
o Function: photosynthesis
Outer Cortex
STEM DICOTS:
o Loosely packed parenchyma
o Function: carb storage
Inner Cortex
STEM DICOTS:
o Innermost layer of cortex
o Thin layer of compact parenchyma
o Usually indistinct
o Cell walls with Casparian strips
o High concentration of amyloplasts
o Function: carb storage, water flow contract (?)
Endodermis
STEM DICOTS:
What is the central cylinder of vascular tissue?
The Stele
STEM DICOTS:
What are the 4 Stele categories/parts?
~Pericycle
~Vascular Bundle
~Medullary Rays
~Pith
STEM DICOTS:
Part of the Stele
Layer several cells thick
Parenchyma and/or sclerenchyma
Pericycle
STEM DICOTS:
___ are fewer & arranged in a ring
open (woody only. Herbaceous are closed), conjoint, usually collateral
Xylem on the inside and phloem on the outside
x/p separate by cambium (woody)
Cambium for secondary growth
Vascular Bundles
STEM DICOTS:
Part of the Stele
Layer of parenchyma between VB
Cells elongated radially (laterally but its circular)
Medullary Rays
STEM DICOTS:
Tissue in center of stem
Loosely packed parenchyma
Function: food storage
Pith
STEMS:
*Describes growth in length of stems
*Stem apical meristem
*Give rise to all above ground organs
*Dense mass of cells at stem tips
*Protected by bud scales & leaf primordia (first order/step)
*SAM & scales & primordia called “bud”
*Bud dormant until growing season
Stem Growth - Primary
3 Primary Meristems?
- Protoderm (produces epidermis)
- Ground meristem (produces ground tissue: pith & cortex)
- Procambium (produces primary xylem & phloem)
STEMS:
What is the first recognizable development stage
Primordia
What are tiny baby leaves called?
Leaf Primordium
What does bud primordium produce?
axillary buds
Elongation of stems from apical meristems
Primary stem growth
Tunica (2) layer names
Epidermal & subepidermal
What does the corpus give rise to?
endodermis, vascular tissue, pith, and pericycle
STEMS:
Where are intercalary meristems located?
Base of each internode (internodes are like a section of bamboo. nodes are the bumps)
Are intercalary meristems monocot or dicots?
Monocots
Why is it good for intercalary meristems to grow from the bottom?
Herbivores, fire, and lawn mowers
STEMS:
Where is secondary stem growth found
Gymnosperms (naked seeds) and Woody dicots
What is the lateral meristem also called?
Cambium (vascular cambium)
STEMS:
What does the vascular cambium form from?
procambium (meristem layer) bundles & cortex cells between bundles
What is a conjoint vascular bundle?
Xylem and phloem together
What is an open vascular bundle?
Able to grow
What is a closed vascular bundle?
Cannot grow
What gives rise to secondary vascular tissue?
Vascular cambium
2 cambium meristem forms?
Fusiform initials and Ray initials
Talk about fusiform initials (orientation and production)
o spindle shaped
o Oriented vertically
o Produce X/P & new cambium cells
Talk about ray initials (orientation & production)
o Oriented horizontally
o Produce vascular rays
What is phellogen?
Cork cambium
STEMS:
Forms from permanent tissues
First from cortex walls, then secondary phloem
Gives rise to outer protective layers
cork cambium
STEMS:
* Cork tissue created outward
* Cells dead & infused with suberin
Phellem
STEMS:
* Living parenchyma created inwards
Phelloderm
STEMS:
Composed of phellogen, phellem, and phelloderm
Periderm
STEMS:
Replaces epidermis in secondary growth
Periderm
STEMS:
What is resins job?
It resists decay and darkens the wood. So the inside is darker and heavier
STEMS:
Barks outer protective layer
periderm, cortex, and secondary phloem
