Studied by 2 people
tree benefits to humans
increase health benefits (decrease human morbidity and mortality) temp decrease/shade for hotter cities
the major groups of plants
annual biennial perennial
annual plants
whole life cycle in one year just the seeds are left
biennial plants
whole life cycles in 2 years short in first year flowering in second year
perennial plants
continuous growth comes back year after year
life cycle types of plants that ONLY do primary growth
annuals biennials
life cycle type of plant that do BOTH primary and secondary growth
perennials
difference between evergreen perennial and deciduous perrenial
evergreen does not drop leaves all at one (individual leaves drop whenever needed) deciduous trees do drop all at once
two types of perennial plants
herbaceous perennials woody perennials
most __________ and _____________________ only have primary growth.
monocots herbaceous eudicots
Roots and stems of _______________________ and ____________________ have primary growth AND secondary growth
gymnosperms woody eudicots
secondary growth
growth in diameter resulting from lateral meristems lateral meristems form secondary tissues
primary growth
growth in length resulting from apical meristems apical meristems form primary tissues
secondary growth occurs in...
regions of a woody plant where primary growth has stopped
two lateral meristems
vascular cambium cork cambium
vascular cambium makes....
secondary xylem secondary phloem
cork cambium makes...
periderm
shape of lateral meristems vs apical meristems
apical meristems are at the tips of roots and shoots lateral meristems are formed in a ring in the innermost cortex
initials of cambium exist in 2 forms
ray initials fusiform initials
ray initials features
horizontally orientated slightly elongated or squarish
ray initial derived from...
meristematic cells from the interfascicular cambium
ray initials become
ray parenchyma cells
ray parenchyma cell function
storage lateral transport of H2O, inorganic and organic nutrients, gases
fusiform initials features
several to many times longer than wide appear flattened or brick-shape in transverse
fusiform initial derived from...
meristematic cells of fascicular cambium
fusiform initials become
secondary xylem and secondary phloem
the "cambial zone" composition
made of meristematic initials and undifferentiated derivatives
cells in vascular cambium can divide by...
periclinal and anticlinal division
periclinal division definition
producing cells to the inside and outside
anticlinal division definition
producing cells to the left and right
periclinal division produces...
derivatives (secondary xylem, secondary phloem, and ray cells)
anticlinal division produces...
more cambial initials
secondary growth enhances the two basic functions of vascular tissue:
transport of water transport of food, molecules, proteins, ions, etc...
rays definition (macroscopically)
lines radiating out from the middle to the outside
ray composition
composed of parenchyma cells
ray functions
storage lateral transport of water, inorganic and organic molecules, and gases
What happens to primary phloem and cortex after secondary growth begins?
new growth crushes and sloughs off older phloem and cortex
Some secondary phloem rays become _____________, forming __________________________
dilated triangular-shaped areas of parenchyma in cross-sections
causes of dilated phloem rays
added circumference prevention of the secondary phloem "popping" off
effects of increasing circumference
sloughs off primary tissue replaces with secondary growth
periderm replaces the ______________ during secondary growth
epidermis
True or false: the periderm originates from the epidermis.
False, the periderm originates from the endodermis in the cortex.
Why can't the epidermis continue to grow as a tree undergoes secondary growth?
Epidermis doesn't have meristematic tissue necessary to continue to grow with it new tissue from inside the cortex will need to push out
cork cambium differentiates into:
cork phelloderm
How does cork cambium initially develop into a cylinder in stems?
starts within single cell layer of cortex
Cork cambium originates from...
the endodermis
Dedifferentiation of ____________________ in a single cell layer in cortex form __________________________, which forms ___________________
parenchyma cells protoderm periderm
periderm consists of three parts:
cork cambium cork phelloderm
cork cambium definition
lateral meristem name
cork relationship to cambium
on outside of cambium
phelloderm relationship to cambium
on the inside of cambium
cork cambium
originates under epidermis in cortex
cork
dead at maturity cork cells lined with suberin and wax contains lenticels
cork fucntion
blocks passage of water and oxygen from suberin and wax
lenticels
allows gas exchange through the periderm
phelloderm
living parenchyma cells lacks suberin and wax layers
phelloderm function
storage
bark parts
inner bark outer bark
outer bark composes of...
all periderm (dead tissue)
inner bark composes of...
living innermost periderm secondary phloem
girdling
removal of outer bark usually caused by beetles, other animals or human-caused
Why does girdling slowly, but not quickly, kill a tree?
removes secondary phloem, so stored food and other molecules can still be used, but once they are used up, the cells slowly die off.
The first-formed cambium may persist for several years. Why is the cork cambium ultimately replaced every few years?
Cork cambium has periclinal, but no anticlinal cell division (meaning, it can only go outward, and not evolve with the added width from the growing secondary xylem)
How and where do new cork cambia develop?
Each new cork cambia arises from parenchyma cells of the cortex deeper in, then from parenchyma cells of the secondary xylem.
bark
all periderms, including the innermost living periderm and the secondary phloem
outer bark
all periderms (dead tissue)
inner bark
living innermost periderm secondary xylem
Why do trees only keep a few years of secondary phloem?
It's replaced by new growing tissue, mostly secondary xylem. It "cracks" the periderm to be sloughed off.
How is corked harvested from cork oak?
Only the outer cork is stripped off and harvested, unlike strip methods that are used for other trees.
Is harvesting the entire outer cork from a cork oak a sustainable practice?
Yes, cork has a large outer periderm, and leaves the inner living parts not damaged. This outer cork regrows in about a decade.
list of external features of a branch
terminal bud lateral bud/axillary bud leaf scar vascular bundle scars lenticels bud scales bud scale scars
terminal bud
the top most bud on a branch, furthest away from the connection point
lateral bud/axillary bud
buds that are on the side of the branch, grows directly from the branch
leaf scar
the horseshoe-like scar left behind where a leaf has falled off
vascular bundle scars
the circular scars within the leaf scar where the vascular bundles were on the leaf before falling off.
bud scales
modified leaves to protect the lateral meristem
bud scale scars
lateral lines where the modified leaves have fallen off also shows annual growth of a branch
How can you measure the age of a branch?
Count the areas between the bud scale scars, that amount is the years that have passed since the branch started forming.
growth rings
rings that are due to the periodic activity of the vascular cambium usually associated with seasonality
Difference of growth rings between temperate area trees and tropical area trees
Temperate area trees usually have one growth ring/year Tropical area trees lack clearly visible growth rings
earlywood
AKA spring wood large cells with relatively thin secondary cell walls seen as larger circles
latewood
AKA summer wood smaller cells with thicker walls seen as smaller circles with more space in between circles
annual rings reveal...
age of the plant artifacts
Width of the rings is a fairly accurate index of...
rainfall historic drought periods historic snow pack levels
Dendrochronology
study of tree rings to apply them to history of forests, the climate, and human civilization, and the connections among them
True or false: The terms "softwood" and "hardwood" do not refer to the density of the plant, but more about the life cycles of the wood.
True
softwoods include...
gymnosperms, conifers
softwood chracteristics
tracheids no fibers and vessels little wood parenchyma very small rays from the naked eye resin ducts
torus
thickened, central portion of the pit membrane
torus composition
middle lamella two primary cell walls
resin ducts definition
large intercellular spaces lined with parenchyma cells that secrete resin into the duct
resin duct function
protection from previous injuries
amber
actual fossilized resin may have parts or entire organisms within in, frozen in time
hardwoods include...
angiosperms
hardwood characteristics
vessel elements tracheids fibers parenchyma cells thicker rays that can usually be seen with the naked eye comes in ring porous and diffuse-porous wood
ring-porous wood
wood with mixtures of early and late wood clearly defined rings
diffuse-porous wood
still has rings, but not visible to the naked eye more common in tropical climates, or areas with more stable temperature/rainfall
heartwood
the older inactive central wood of a tree or woody plant usually darker and denser than the surrounding sapwood
sapwood
newly formed outer wood lying between the cambium and the heartwood of a tree or woody plant usually light colored
Can a tree live without heartwood?
yes
Note
Flashcard