Exam 2 Notes Flashcards
shoot
stem and leaves, flowers and buds
stem
an axis for stalks with no side structures attached, used for support and conduction
function of stems
conduction of xylem and phloem
support of leaves and other above ground parts of plants
storage
photosynthesis
origin and growth of primary tissues of stems
organization of short apical meristem amore complex than root
reason of primary growth in stems
formation of leaves
node of stem
site of attachment of leaf on stem
internode of stem
area of stem where no leaves are attached
3 basic types of organization of seed plants
- primary vascular tissues develop as a cylinder of discrete strands separated from one another by ground tissue
- primary vascular tissues appear as a more or less continuous hollow cylinder with ground tissues
- vascular bundle scattered throughout the ground tissue
pith in stem
ground system
pith in root
vascular system
what does vascular cambium give rise to in the 2 organization of stems
wood
does all 3 stem organization have a pith or cortex
no
leaf trace
extensions of vascular bundles from vascular system in stem toward the leaves
leaf gap
regions of ground tissue in vascular cylinder above area where leaf traces extend toward leaves
modifications of stems
1 stolons or runners- reproductive 2 tendrils 3 thorn 4 succulent stem 5 rhizomes 6 bulbs 7 corms 8 tubers
rhizomes stem modification
reproductive, below ground
bulbs stem modification
storage structure, mostly leaf
corms stem modification
storage mostly stem
tubers
storage below ground
secondary growth in stems
at start of each growing season primary growth occurs from apical meristem
additional secondary tissues are added via secondary meristems
is secondary growth in stem dicot, monocot, or both
dicot only
what are the secondary meristems
cork cambium and vascular cambium
vascular cambium
ring of meristemic cells that adds girth to stem
cell division to the outside produces secondary phloem and to the inside is secondary xylem (wood)
vascular rays
produced by vascular cambium
mostly parenchyma cells
pathways for lateral movement
storage areas
wood sections
cross section
radial section
tangential section
cross section of wood
right angle to long axis of stem or root
growth rings are arranged in concentric circles
rays radiate from center
radial section of wood
longitudinal cut that goes through center of stem
growth rings appear as parallel lines oriented perpendicular to rays
rays appear as sheets of cells
tangential section of wood
longitudinal cut that does not go through the center of stem
growth rings arranged in large irregular patterns of concentric “v’s”
cut at right angle to rays, reveals width and height of rays
2 sections of bark
outer bark
inner bark
outer bark
all tissues outside cork cambium
non living cork
inner bark
tissues between cork cambium and vascular cambium
tissues are living,
secondary phloem, cortex, phelloderm
conifer wood
soft woods homogenous in appearance (same) few cell types (tracheids) no vessel elements rays only 1 cell wide
angiosperm wood
hard woods
heterogenous in appearance (different)
many cell types (tracheids, vessel elements, fibers, parenchyma)
rays in TS can be more than 1 cell wide
function of secondary phloem
little secondary phloem is involved in transport of food
older sieve elements become crushed
newer sieve elements replace them
periderm
replaces epidermis as the outer protective layer formed by cork cambium
cork cells
inner walls lined with suberin and wax
highly impermeable to water and gases
at maturity cork cells are dead
phelloderm cells living at maturity
lenticels
inner tissues of stems need to exchange gases with surrounding air
accomplished by lenticels
lenticels definition
holes through periderm
bark
all tissues outside of vascular cambium
leaf
structure subtends the bud
phyllotaxy (leaf arrangement)
whorled
opposite
alternate
whorled phyllotaxy
3 or more leaves per node
opposite phyllotaxy
2 leaves per node
alternate phyllotaxy
1 leaf per node
simple leaf
blade in one piece or section
complex leaf
blade in several pieces or sections (leaflets)
function of leaves
usually the most conspicuous organ of plant
photosynthesis
what is the primary function of leaves
photosynthesis
expose large amounts of surface area
mesomorphic leaf
standard leaf
hydromorphic leaf
grow wholly or partially submerged in water
large air spaces present (aerenchyma)
thin cuticle
xeromorphic leaf
adapted to arid habitat features to conserve water thick cuticle sunken stomata often multiple epidermis, trichomes
leaf epidermis
cells compactly arranged and transparent
covered with waxy cuticle to reduce water loss
stomata can occur on both surfaces, but usually more numerous on lower side
scattered stomata on leaf
dicot
rows of stomata on leaf
monocot
mesophyll
ground tissue in leaf interior of leaf between epidermis layers large numbers of intercellular spaces large number of chloroplasts in cells area specialized for photosynthesis
palisade parenchyma
mesomorphic leaf
cells into column
long axis of cells at right angle to epidermis
usually on upper side of leaf
area for capturing light
spongy mesophyll
mesomorphic leaf
cells are irregular in shape and arrangement
generally on lower side of leaf
much intercellular space facilitates gas exchange
xeromorphic leaves
palisade parenchyma can occur on both sides of leaves
grass leaves
mesophyll cells are very similar and usually not in palisade or spongy layers
dicot leaf venation
netted
monocot leaf venation
parallel
leaf veins
both xylem and phloem extend to end of vein
phloem on lower side and xylem on upper
kranz (wreath) anatomy
“warm season”
C4 photosynthesis
large bundle sheath cells that are full of chloroplasts and closely spaced veins
C3 photosynthesis
“cool season”
smaller bundle sheath cells with few chloroplasts and widely spaced veins
epidermis of grasses
several types of cells
bulliform
bulliform
large inflated epidermal cells rolling and unrolling of leaves
sun and shade leaves
environmental factors, especially light, can have substantial effects on the size and thickness of leaves
sun leaf
small and thicker than shade leaves
due to greater development of palisade parenchyma
often multiple layers of palisade cells
shade leaf
large and thin
have fewer well defined mesophyll layers
have fewer chloroplasts than sun leaves
leaf abscission
normal separation of leaf from stem
preceded by the structural and chemical changes near base of leaf petiole
results in abscission zone
2 layers of leaf abscission
separation layer
protection layer
separation layer
on leaf side
cells swell and become gelatinous
protection layer
on stem side
composed of heavily suberized cells
leaf modifications
tendril- support spines- defense food storage leaves of bulb cabbage "head" celery leaves and leaf stalk bracts insectivorous reproductive leaves water storage arid leaves bud scales flower pot leaves window leaves
cabbage “head” leaf modification
consists of short stem with many thick overlapping leaves
celery leaves and leaf stalk leaf modification
petioles become fleshy and very thick
bracts leaf modification
floral like leaves that from at the base of flowers or inflorescence
insectivorous leaf modification
insect trapping leaves
reproductive leaves leaf modification
asexual
water storage leaf modification
leaves are succulents and specialized for water storage