Please enable JavaScript.
Coggle requires JavaScript to display documents.
Leaves (Morphology and anatomy of other leaf types (bud scales (form tight…
Leaves
Morphology and anatomy of other leaf types
succulent leaves
permit plant to survive in desert
shape favors H2O conservation
very few air spaces->reduce evaporation
leaves of conifers
#
bud scales
form tight layer around stem tip
protect dormant apical meristems
most common modification of leaves
function in protection
spines
cacti leaves
protection from predators
leaves with Kranz anatomy
in plants with C4 photosynthesis
lack palisade and spongy
prominent bundle sheaths
arid environments
insect traps
in habitats poor in nitrate and ammonia
classified as active or passive traps
sclerophyllous foliage leaves
extended lifetime & prolonged productivity
hard
tendrils
grow indefinitely
modified leaf
cells sense contact
External structure
leaf blade
AKA lamina
may be simple or compound
simple leaf has blade of just one part
compound leaf has blade divided into several parts (leaflets)
light harvesting
flat
dorsal surface
blade's lower side
AKA abaxial side
veins protrude like backbones
ventral surface
AKA adaxial
smooth
petiole (stalk)
holds the blade into light
prevents self-shading
leaf with petiole is called a petiolate
leaf without petiole is called sessile leaf
leaf base wraps around stem instead
sheathing leaf base
#
extension called rachis
abscission zone
cells cut off leaf when no longer useful
in autumn
forms leaf scar
veins
bundles of vascular tissue
distribute H2O :
collect sugars produced by photosythesis :explode:
reticulate venation
netted pattern
in eudicots and angiosperms
Internal structure
epidermis
transpiration
water loss through epidermis :no_entry:
mesophyll
ground tissues interior to epidermis
palisade parenchyma (mesophyll)
main photosynthetic tissue :recycle:
intercellular spaces so CO2 dissolves slowly in cytoplasm
spongy mesophyll
lower portion of leaf
open, loose aerenchyma
CO2 diffuses rapidly from stomata to interior
vascular tissues
between palisade and spongy
minor veins <- lateral veins <- midvein
bundle sheath
fibers arranged around vascular tissues
protection
bundle sheath extentsion
rigidity
water transport from bundle to mesophyll
petiole
transition between stem and lamina
leaf traces diverge from vascular bundles to petiole
stipules
two small flaps of tissue at base of petiole
protect apical meristem
photosynthesis contribution in large plants
variation in arrangement of bundles
Initiation and development
basal angiosperms and eudicots
cells grow from apical meristem to form leaf primordium
leaf primordium extends upward as narrow cone
establishes bulk of midrib (midvein)
cells on either side initiation lamina
perennial plants
leaves initiated in summer or autumn
monocots
constant basal expansion
