2 ... 13 - Roots Flashcards
Major root functions?
anchorage
absorption
conduction
storage
Main forms of root structures?
fibrous system
tap root system
Describe tap root system
one prominent main root with small, lateral roots branching from it
Describe fibrous root system
many adventitious roots of ~equal size, arising from stem base
Monocots typically have ___ root systems.
fibrous
Eudicots typically have ___ root systems.
tap
RAM…
root apical meristem
Three zones of growth in root?
- zone of cell division (includes meristem… ‘bottom’)
- zone of elongation (cell expansion… middle)
- zone of maturation (cell differentiation… top)
Describe root cap
covering of cells over root tip that protects delicate meristematic tissue directly behind it
Define root hair
extension of epidermal cell of root that greatly increasing absorptive capacity of root (maturation zone)
Basic root structure, inside out?
Vascular tissue
Endodermis
cortex
root cap/epidermis
Describe eudicot roots
xylem and phloem form solid mass in center known as vascular center (surrounded by pericycle and endodermis)
Describe monocot roots
pith in center, surrounded by ring of vascular tissue
Function of epidermis?
protects root, … hairs help absorb water and dissolved minerals
Function of cortex?
stores starch, consists of parenchyma cells
Describe endodermis
innermost layer of root cortex, prevents water and dissolved minerals from simply entering xylem… forces everything to enter by passing between cells
Two ways of moving water in root cortex?
- symplasticly
2. apoplasticly
Symplastic water movement
intracellular, through cells (cytoplasm) … casparian strips
Apoplastic water movement
interconnected cell-wall spaces
Describe casparian strips
band of waterproof material around cell walls of endodermis… ensures water and minerals enter xylem ONLY by passing THROUGH endodermal cell interior
Describe pericycle
layer of cells just inside endodermis of root (outermost layer of vascular tissue)… where lateral roots emerge
Describe adventitious roots
roots that develop from stem… thicker, provide extra support. aka prop roots
other ways roots can absorb water and nutrients from soil?
- mycorrhizae
2. nodules
Describe mycorrhizae.
mutualistic fungi/root relationship. helps absorb minerals from soil… increases surface area
Describe nodules.
small swelling on root in leguminous plant… N-fixing bacteria live here
