Chapter 6 Flashcards
Stems
Grafting
Artificially uniting stems or parts of stems
Indeterminate Growth
Plants can grow indefinitely
A woody twig consists of
an axis with attached leaves
Alternately arranged
Occurs when the leaves are attached to the twig alternately or in a spiral.
Opposite arrangement
If the leaves are arranged in pairs
Whorled
Groups of 3 or more leaves
Node
The area or region of a stem where a leaf or leaves are attached
Internode
Stem region between nodes
Blade
Flattened part of leaf
Petiole
A flexible stalk made of collenchyma cells that attaches leaf to stalk
Each angle between a petiole and the stem contains a
bud
The angle is called an
axil
Axillary Bud
the bud located in the axil
Angiosperms
flowering plants
Axillary buds may become
branches
or, axillary buds may develop into
the next season’s flowers
Most buds are protected by
bud scales
Where is the terminal bud often located?
At the tip of each twig
Terminal buds do not become
separate branches
Meristems within the terminal bud
Produce tissues that make the twig grow longer during the growing season
Bud scale scars
left behind when the scales fall off of a terminal bud
What can you determine by counting the bud scale scars?
Age of twig
Stipules
Paired, often leaflike appendages that remain throughout the life of the leaf.
Stipule Scars
are left behind if the stipules fall off of a twig.
Deciduous trees and shrubs
lose their foliage annually
Deciduous plants’ axillary buds
often remain dormant with leaf scars below them after the leaves fall
Bundle scars
mark the location of xylem and phloem, usually visible within leaf scar
Apical Meristem
Tissue in which cells actively divide, found in the tip of each stem.
Primordia/Primordium
Embryonic leaves that will develop into mature leaves after the bud scales drop off and growth begins
Protoderm
gives rise to the epidermis, outermost of the three meristems developed from mitosis in the apical meristem
Epidermis
typically one cell thick, usually becomes coated with a thin, waxy, protective layer called the cuticle.
Procambium
Interior to the protoderm, Produces water conducting primary xylem and primary phloem cells that have several functions, including transportation of food.
Ground Meristem
Produces two tissues composed of parenchyma cells
Pith
Made up of the parenchyma tissue in the middle of the stem
Cortex
Closer to the outside of the cell, eventually forms bark as it is pushed out
Both the pith and the cortex function in
storing food, or if chloroplasts are present, manufacturing it.
Primary tissues
Epidermis, primary xylem, primary phloem, pith and cortex
As primary tissues are produced
the leaf primordia and bud primordia develop into mature leaves and buds
Trace
A strand of xylem and phloem branches off from the vascular tissues cylinder, extending up or down the stem and entering the leaf or bud
Each trace leaves a little thumbnail shaped gap in the cylinder of vascular tissue called
leaf gaps and bud gaps, both are filled with parenchyma tissue
Vascular Cambium/Cambium
Cells in this area divide indefinitely.\
The secondary tissues of the vascular cambium add to
girth
Cells produced by the vascular cambium become
tracheids, vessel elements, fibers, or other components of secondary xylem
Functions of the secondary tissues
Same as those of their primary counterparts, conduct food and water
Cork Cambium/Phellogen
produces box like cork cells
Cork cells become impregnated with
Suberin
Suberin is a
waxy substance that makes cells impervious to moisture
the cork cells are produced
annually in cylindrical layers, die shortly after formed.
Phelloderm cells
Produced towards the inside of the cork cambium, parenchyma like cells.
As woody stems age,
LENTICELS are formed underneath the stomata
Stele
made up of primary xylem, primary phloem, and the pith
Protostele
simplest form of stele, consists of a solid core of conducting tissues in which the phloem usually surrounds the xylem
siphonosteles
tubular with pith in the center, common in ferns
Eusteles
found mainly in present day flowering plants and conifers.
Cotyledons
Seed leaves
Dicotyledons
two cotyledons
Monocots
Single cotyledon
Annuals
die after one growing season, generally have green herbaceous stems
Vascular bundles
comprised of patches of xylem and phloem
Heartwood
Older, darker wood at the center of tree
Sapwood
Lighter, still functioning xylem closest to the cambium
Bark
All tissues outside of the cambium, including the phloem
Laticifers
specialized ducts or cells found in about 20 families of herbaceous and woody flowering plants
What do laticifers do?
form extensive branched networks of latex secreting cells originating from rows of meristematic cells
Dicot stem cross section
more like a pie, big vascular bundles evenly spaced, identical cuts.
Monocot stem cross section
Chocolate chip cookie, spaced out small vascular bundles surrounded by water storing parenchyma cells.
Rhizomes
Horizontal stems that grow below ground, often near the surface of the soil
Runners
horizontal stems that differ from rhizomes because they grow above ground, generally at the surface. They have long internodes
Stolons
similar to runners but produce beneath the surface of the ground and tend to grow in different directions, usually not horizontally.
tubers
internodes at the tips of stolons that swell from the accumulation of food.
Bulbs
large buds surrounded by numerous fleshy leaves with a small stem at the lower end. stores food
Corms
Similar to bulbs but have a papery outside, Gladiolus and crocus are examples
Cladophylls
flattened and appear leaf like.
Cacti
Thorns
an example of a modified stem
Tendrils
Climbing parts of the stem that use anything they can touch to their advantage
Density of wood
weight per unit of volume
Durability
the ability to withstand elements and decay
Knots
the bases of lost branches that have become covered over time.
Adaxial
Upset surface of leaf
Abaxial
Bottom surface of leaf.
aBaxial-Bottom
