exam 1 slide 5 and 6 Flashcards
Complex Tissues
Comprised of More
than one Cell Type
complex tissue types
a. Epidermis
b. Xylem
c. Phloem
d. Periderm
e. Secretory
a. Epidermis
-where is it
-how large is it
-are there hairs if there are what type of hairs
– Outermost layer of cells on plant organs (e.g.
leaves, roots, stems)
– Usually one cell thick
– Hairs are often present
* Trichomes
.Root hairs
Trichomes
hairs on stems, leaves and other above
ground structures that are projections of epidermal
cells or a number of epidermal cells
Root hairs
extensions of epidermal cells
Upper Epidermis of Tobacco Leaf
-whats on it and what are there functions
Waxy Cuticle on Surface
* Epidermal Cells
* Stomatal Guard Cells
– Water and gases pass
through stomates
* Hairs = glandular trichomes
Tradescantia Leaf Epidermis
have what
.Trichomes
* Regular epidermal
cells
* Guard cells
* Subsidiary cells
Xylem
roles
– Water and mineral conduction (transport)
* Transport is upwards and sideways
– Support
– Some storage
Components of Xylem:
-Xylem parenchyma cells
-fibers
-conducting components
-vessels
-tracheids
rays of parenchyma in wood
fibers in xylem is used for
support
the xylem parenchyma cells are used for
storage
what make vessels diffrent from tracheid
-Long tubes made up of
vessel elements (cells)
* Can be open-ended or have
bar-like strips at the end
walls = perforation plates
* Can have pits in side walls
what makes tracheids diffrent form
.Narrower
* Tapered at the ends
* Pits in end walls and
side walls
what do Vessels and Tracheids both have
- Both have primary and secondary walls
- Both have lignin in the secondary walls that
stains red with phloroglucinol-HCl - Both are dead at maturity
- At maturity, the cells have no cytoplasm and
are empty - Both have pits or ring-like thickenings or other
patterns of lignin in secondary walls
Phloem
what do they do
-Transport of dissolved “food” = carbohydrates
* Direction of transport is up & down and sideways
* Source sink relationships determine direction of
transport in phloem
From a source of
carbohydrate
-Photosynthesizing leaves
* Other sites of
photosynthesis
* Underground storage
structures that are
exporting (e.g. bulbs in
spring)
* Mature structures that are
exporting
To a sink for carbohydrates
- Growing leaves
- Growing fruits
- Growing flowers
- Growing buds
- Developing roots
- Developing, importing
underground storage
structures
Components of Phloem:
-Phloem parenchyma cells = storage
* Fibers for support
* Conducting components
– Sieve tube cells
– Companion cells
* Rays of parenchyma in wood
both Sieve Tube Cells and Companion Cells
- Both have primary walls only
- They do not stain red with phloroglucinol-HCl
- Both are alive at maturity
Sieve tube cells (elements) are diff because
-Lack a nucleus
* Wider in diameter
* Sites of transport
* Have sieve plates at end
walls
Companion cells are diffrent bcuz
-Have a nucleus
* Narrower in diameter
* Aid the transport process
Xylem in
Cone Bearing Trees (Gymnosperms)
Xylem = tracheids only, no vessels, no fibers
– Cone-bearing trees = softwoods
only diff in phloem from xylem in gymnosperm
Phloem has albuminous cells instead of
companion cells, but is otherwise similar to xylem
Periderm where to find them
outer bark of woody plants
Periderm is made of what and what are some of its roles
-Phelloderm
* Cork cambium (phellogen) = source of cells
* Cork cells
how do cork cells work in periderm
– Dead at maturity
– Have fatty suberin in cell walls for waterproofing
Secretory tissue that releases
-Nectar (from flowers and leaves)
– Oils (e.g. citrus oils)
– Resins (e.g. from conifers)
– Waxes
– Poisons
– Latex (e.g. Norway maple, Poinsettia)
– Enzymes
– Mucilage (glue) e.g. Sundews
gymnosperm are diff cause
- “Naked” seeds
- Have seeds but not in fruits
- Seeds often in cones
- No flowers
Angiosperm diff cause
-“Vessel” seeds
* Seeds are in fruits
* Flowers
-monocot
-dicots
Monocots (monocotyledonous)
one cotyledon (one seed “leaf”)
Dicots (dicotyledonous)
two cotyledons (two seed “leaves”)
Node
the site on the stem where one or more
leaves is attached.
Internode
the region in between two nodes
Bud scales
Protect the bud; bud scales leave scars
when they fall off
From one set of bud scale scars to the next, is one year’s
growth
Lenticels
*Loosely arranged pockets of parenchyma cells that protrude
through the surface of periderm (outer bark).
*On woody stems that no longer have an epidermis and no
longer have stomates.
*Allow for gas exchange.
Typical Monocot Vascular Bundle
-Some large vessels with
several small vessels
* First formed xylem cells
stretch and collapse leaving
air space
* Phloem consists of sieve
tubes and companion cells.
* No vascular cambium
* Closed vascular bundles
Closed vascular bundles
vascular bundles are
surrounded by sheath of
sclerenchyma cells.
Monocot Stem
- Scattered vascular bundles
- Ground or fundamental tissue of parenchyma
cells instead of pith and cortex - No vascular cambium in vascular bundles
- Closed vascular bundles
- Do not form true wood
- Do not form cork (no cork cambium)
herbaceous
dicot stem
-herbaceous dicots have discrete vascular bundles arranged in
a cylinder or ring
* Vascular cambium arises between primary xylem and primary
phloem (the xylem and phloem in the original bundle).
– Adds secondary xylem and secondary phloem
Dicot Stems
-Vascular bundles in a ring
* Pith and cortex of parenchyma cells instead of
fundamental or ground tissue
* Vascular cambium in vascular bundles
* Open vascular bundles
– NOT surrounded by bundle sheath
* Can form true wood (depends on the species)
– Wood = secondary xylem
Secondary (Thickening) Growth
Vascular cambium:
Vascular cambium produces secondary xylem and secondary phloem where
Produces secondary xylem to the inside
– Produces secondary phloem to the outside
Vascular Rays
Vascular Rays consist of parenchyma cells that
function in lateral conduction of nutrients and water
vascular rays and xylem rays
Xylem Ray - Part of ray within xylem
–Broad xylem ray
–Narrow xylem ray
vascular rays and phloem rays
Phloem Ray - Part of ray through phloem
–Broad phloem ray (continution of broad
xylem ray)
–Narrow phloem ray (continuation of narrow
xylem ray)
Spring wood is formed
early in the season and
has wider diameter vessels than summer
wood. It is also lighter in color.
Summer wood
has thicker walls and is darker in color. has a tinner diameter vessesls
When summer wood of the previous season is
next to spring wood of the next season
a line
can be seen between them and this is the
annual ring.
Earlywood
Spring wood
Latewood
Summer wood
Heartwood and Sapwood similarties
(Both are dead; all wood is dead)
Resins, gums, and tannins
accumulate, and darken wood,
forming heartwood.
Heartwood
Older, darker wood in center
* No longer functions in transport
* Still provides support
sapwood
-Lighter, closest to cambium
* Still transports
* Provides support
One year’s growth of the xylem are called
and what creates the ring
annual ring
Vascular cambium produces more secondary xylem
than phloem
Bulk of tree trunk consists of annual rings of wood.
what does it indicate and reflect
– Indicates age of a tree
– Reflects growth conditions during tree’s lifetime
– e.g. precipitation, forest fires
Woody Pine Stem have what and what type of wood is it
Resin canals
The wood is tracheids only
and is a softwood
Resin canals
Secrete resin or “pitch” for protection after
wounding. Turpentine evaporates and leaves rosin.
woody pine stems wood is tracheids only
-No vessels
– No fibers
Removal of Wood
-Heartwood supports the
tree but cannot conduct
materials.
– A tree may still function
after heartwood is
removed.
* It is possible to remove
portions of sapwood
without destroying the tree.
– Coastal redwoods of
California
Specialized Stems
Rhizomes
runners
tubers
bulbs
corms
thorn
rhizomes
Horizontal stems that grow below-
ground; have nodes and internodes
irises
runners
Horizontal stems that grow
above ground and have long internodes.
e.g. Strawberry
Tubers
Swollen, fleshy,
underground stems
– Store food
– e.g. Potatoes – Eyes of potatoes are
nodes
Bulbs
Stem and leaves
– Store food
– e.g. Onions, hyacinths, tulips
corms
Mostly stem tissue with
papery leaves
– Store food
– e.g. Crocus and gladiolus
