Roots (Quiz 2) Flashcards
Acacia koaia =
not on test
rare dryland Hawaiian tree
acacia koaia with
not on test
juvenile (pinnately compound) leaves & phyllodes (sickle shaped)
early plants with shoots =
& ex?
no vascular tissue or roots
ex: Aglaophyton
early plants (nonvascular/no roots) had (2)
- ) lateral shoot (below ground = “rhizome”, above ground = “runner”)
- ) rhizoids (one cell thick)
likely precursors to roots =
rhizomes
rhizoids homologous to
trichomes
Lycopodium =
basal vascular plant w/ roots
lycopodium had same body plan as
& whats the main difference between them?
Aglaophyton
& lycopodium exhibits microphylls (leaf with branching veins) and roots!
Lycopodium exhibited (2)
- ) dichotomous branching
2. ) reproductive structures at tips
2 basic types of roots:
- ) adventitious
2. ) Roots from other roots
adventitious roots evolved
& develop from
first
the shoots
adventitious roots can form
in any group of vascular plants
roots from other roots occur in
seed plants
roots from other roots develop from
the seed root
- radicle
- other roots develop from the original root
root function: (4)
- ) water & nutrient uptake
- ) anchoring
- ) storage
- ) photosynthesis (some orchids have shoots w/ only flowers & photosynthesize through roots)
root zones can be separated
into different zones of development
root zones:
& characteristics of them
- ) zone of cell division (bottom tip) (apical meristem and associative areas)
- ) zone of elongation (where growth occurs; some tissue differentiation & maturation)
- ) zone of differentiation (towards base of root) (maturation is where the stele matures and root hairs (aka trichomes) elongate)
root hairs function
help in nutrient/water uptake
ZOD is where
X, P, & root hairs/trichomes mature
root hairs are only found in
the ZOD
Root tip structures: (3)
RAM (root apical meristem)
Quiescent center
Root Cap
RAM functions
divides to the outside –> root cap
& divides to the inside –> body of the root
Root cap functions: (3)
- protection of RAM
- produces mucilage (to prevent desiccation)
- senses gravity (using statoliths)
Quiescent center has
dormant (non dividing) stem cells
Statoliths are located
in the columella of the root cap
statoliths are
specialized amyloplasts that signal the direction of gravity
steles are described by
of poles in X
2 = diarch 3 = triarch 4 = tetrarch 5 = pentarch 6 = polyarch
Endodermis =
innermost layer of the cortex
meta X =
proto X =
new X
old X
meta vs proto (transport)
meta cna transport more per cell than proto
cortex is made up of
parenchyma
endodermis function
produces casparian strip
casparian strip forms
on radial walls
casparian strip is comprised of
lignin & suberin (sometimes)
Types of water movement in steles: (2)
- ) Apoplastic –> movement along CW’s or intercellular space (can happen from root hairs to X in dicot)
- ) Symplastic –> movement through cytoplasm “cell - cell” (through channels or plasmodesmata)
Pericycle cells =
totipotent
Pericycle function: (3)
- produces lateral roots
- produces part of vascular cambium @ X poles
- produces cork cambium
roots branch…
endogenously (to protect meristematic tissue)
exogenous branching =
w/ axillary buds
most roots have no
pith
roots w/ pith =
monocots (corn, sugarcane)
roots w/ 2* growth exhibit (2)
loss of their cortex
1* P gets pushed out from OG position
root types (4)
- ) taproots –> usually from radicle (dandelion)
- ) fibrous roots (adventitious) –> usually not in woody plants (grass)
- ) prop roots (adventitious) –> corn (corn)
- ) aerial roots (adventitious) –> originated aboveground (orchid)
prairie plant roots
are deep, despite herbaceous shoots
some prairie plant roots
have long taproot systems
many prairie plant roots are
“fibrous”
roots produced by stems =
adventitious
red mangrove roots grow
down into soil after floating to good location for establishment
red mangrove roots can
also produces prop roots w/ loads of air canals (because red mangroves are closest to the ocean)
black mangrove roots produce
pneumatophores w/ air canals & lateral roots (to oxygenate roots below water level)
black mangroves grow
more inland
