Stems Flashcards
It is a large source of wood and has a wide variety of application.
Stems
Artificially uniting stems of related varieties of plants. It has been used by humans for centuries.
Grafting
Consists of an axis with attached leaves
Woody twig
if leaves are attached alternately.
Alternate
if attached in pairs.
Opposite
if in groups of three or more.
Whorled
It is the arrangment of leaves
Phyllotaxy
Area of stem where leaves are attached
Node
They are regions between nodes.
Internodes
Leaf has a flattened blade and is usually attached to the twig in stipules. True or false?
False, it is attached by petioles.
Angle between petiole and stem
Axil
_____ are in axil. It will become branches or flowers in flowering plants
Axillary buds
______ protect buds.
Bud scales
● Found at twig tips
● Growth makes twig longer.
Terminal buds
Number of groups of bud scale scars tells age of twig. True or false?
True
Paired, often leaflike appendages at base of a leaf. It protects the growing bud
Stipules
Plants that lose all leaves annually. They have dormant axillary buds with leaf scars below
Deciduous plants
Marks food and water conducting tissue within leaf scars
Bundle scars
● Contributes to increase in stem length
● Dormant before growing season begins
Apical meristem
Leaf primordia are tiny embryonic leaves that develop into mature leaves. While bud primordia are embryonic buds in the axils of the leaf primordia. True or false?
True
It gives rise to epidermis
Protoderm
It produces primary xylem and phloem
Procambium
It produces pith and cortex.
Ground meristem
Strands of xylem and phloem
Traces
Narrow band of cells between the primary xylem and primary phloem may become ___________
vascular cambium
It cuts off water and food to epidermis
Cork Tissue
Cork tissue is specially found in woody species which soon dies and is sloughed off. If the cork were to be formed as a solid cylinder covering the entire stem, vital gas exchange with the interior of the stem would not be possible. True or false?
True
Pith and cortex are both composed of schlerenchyma cells. True or false?
False, they are composed of parenchyma cells
● Also called phellogen
● Produces cork cells with suberin and phelloderm cells
● Reduces water loss and protects stem injury
Cork Cambium
In young stems, gas exchange takes place at _______
Stomata
Older stems develop _________. It is an alternate source of gases.
Lenticels
Central cylinder of primary xylem, primary phloem, and pith (if present)
Stele
● Solid core of phloem surrounding xylem
● Found in primitive seed plants, whisk ferns, club mosses and ferns
Protostele
● Tubular with pith in center
● Common in ferns
● No solid form
Siphonostele
● Type of siphonostele
● Discrete vascular bundles
● In flowering plants and conifers
Eustele
● Seed leaves attached to embryonic stems
● Store food needed by young seedling
Cotyledons
● Flowering plants that develop from seeds having two cotyledons
Dicotyledons
● Flowering plants that develop from seeds with a single cotyledon
Monocotyledons
Plants that die after going from seed to maturity within one growing season
Annual Plants
Most monocots are annuals, but many dicots are also annuals. True or false?
True
● Discrete vascular bundles arranged in a cylinder
● Vascular cambium arises between primary xylem and primary phloem.
Herbaceous Dicotyledonous
______ is secondary xylem.
Wood
Spring and summer wood alternate as light and dark rings. True or false?
True
Relatively large vessel elements of secondary xylem produced
Spring wood
Fewer, smaller vessel elements in proportion to tracheids and fibers
Summer wood
● Vessels and fibers absent
● Tracheids in spring larger than later in season.
Conifer Wood
● One year’s growth of xylem
○ Indicates age of a tree
○ Indicates climate during tree’s lifetime
Annual Rings
Vascular cambium produces more secondary phloem than xylem. True or false?
False, it produces more secondary xylem than phloem.
● Consist of parenchyma cells that function in lateral conduction of nutrients and water
● Xylem ray is part of ray within xylem.
● Phloem ray is part of ray through phloem.
Vascular Rays
________ is older, darker wood in center. Formed from Resins, gums, and tannins accumulate and darken wood
Heartwood
_________ is lighter, still-functioning xylem closest to cambium.
Sapwood
Heartwood supports the tree but cannot conduct materials. A tree cannot function after heartwood is removed. True or false?
False, a tree may still function after the heartwood is removed but it cannot function if sapwood is removed.
It is the wood of conifers.
Softwood
It is the wood of dicot trees.
Hardwood
● Tubelike canals scattered throughout xylem and other tissues
● Lined with cells that secrete resin
Resin Canals
Tissues outside the vascular cambium, including phloem
Bark
○ Inner bark consists of primary and secondary phloem.
○ Outer bark (periderm) consists of cork tissue and cork cambium.
True or false?
True
● Ducts found mostly in phloem that have latex-secreting cells
Laticifers
● No vascular nor cork cambium
○ Produce no secondary vascular tissues or cork
● Primary xylem and phloem in discrete vascular bundles scattered in stem
Monocot Stems
● Two large vessels with several small vessels
● First-formed xylem cells stretch and collapse.
○ Leave irregularly shaped air space
● It is surrounded by sheath of sclerenchyma cells.
Monocot Vascular Bundle
Horizontal stems that grow below-ground and have long to short internodes
Rhizomes
Horizontal stems that grow above ground and have long internodes. They form adventitious roots
Runners
Produced beneath the surface of the ground and tend to grow in different directions.
Stolons
Swollen, fleshy, underground stem, store food
Tubers
Large buds surrounded by numerous fleshy leaves, with a small stem at lower end. Made up of mostly leaves and has thin stem
Bulbs
Resemble bulbs, but composed almost entirely of stem tissue, with papery leaves. Made up of mostly stems
Corms
Flattened, leaf-life stems that photosynthesize.
Cladophylls
A very thin sheet of desirable wood glued to cheaper lumber.
Veneer
Used to make paper, synthetic fibers, plastics, and linoleum. It is second most widespread use of wood.
Pulp
More than 50% of timber is used as fuelwood worldwide. True or false?
True
