chapter 36 Flashcards
2 groups of Angiosperm—not taxonomic categories
Tissues are the same but they are arranged differently in the
roots, stems and leaves
Monocots
herbaceous—do not form wood; only have primary tissues flowers—parts are in threes or multiples of threes
leaf veins are parallel
Eudicots
herbaceous and woody (have secondary tissues)
flowers—parts are in fours or fives or multiples of fours
or fives leaf veins are net-veined
Plant Body Organization
A vascular plant consists of
Root system
Anchors the plant
Used to absorb water and ions
Shoot system
Consists of supporting stems, photosynthetic leaves, and reproductive flowers
Iterative unit consists of internode, node, leaf, and axillary bud
3 basic tissue types
Dermal – outer protective cover
Ground – function in storage, photosynthesis, and secretion
Vascular – conducts fluids and dissolved substances
Tissues consist of one or more cell types
Meristems –areas of active cell division
apical meristems—extension of shoot and root
shoot meristem—tips of stems
root meristem—tips of roots
lateral meristems produce an increase in shoot and root diameter vascular cambium cork cambium
Apical meristems—give rise to primary tissues which are collectively called the primary plant body
Apical meristems composed of delicate cells that need protection
Root cap protects root apical meristem
Leaf primordia protect shoot apical meristem
Lateral meristems
Found in plants that exhibit secondary growth
Give rise to secondary tissues which are collectively called the secondary plant body
Woody plants have two types
Cork cambium produces outer bark
Vascular cambium produces secondary vascular tissue
Secondary xylem is the main component of wood
Secondary phloem
Plant Tissues
Three main types of tissue
Dermal (epidermis)
On external surfaces that serves a protective function
Ground (cortex, pith, mesophyll (leaves))
Forms several different internal tissue types and can participate in photosynthesis, serve a storage function, or provide structural support
Vascular (xylem, phloem)
Conducts water and nutrients
Dermal Tissue
Forms the epidermis
One cell layer thick in most plants
Forms the outer protective covering of the plant
Covered with a fatty cutin layer constituting the cuticle
Contains special cells, including guard cells, trichomes, and root hairs
Guard cells
Paired sausage-shaped cells
Flank a stoma – epidermal opening
Passageway for oxygen, carbon dioxide, and water vapor
Trichomes
Cellular or multicellular hairlike outgrowths of the epidermis
Keep leaf surfaces cool and reduce evaporation by covering stomatal openings
Some are glandular, secreting substances that deter herbivory
Roots hairs
Tubular extensions of individual epidermal cells
Greatly increase the root’s surface area and efficiency of absorption
Should not be confused with lateral roots
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Ground Tissue(cortex, pith, mesophyll)
3 cell types Parenchyma Function in storage, photosynthesis, and secretion Collenchyma Provide support and protection Sclerenchyma Provide support and protection
Vascular Tissue
Xylem
Principal water-conducting tissue, conducts
inorganic ions and supports the plant body
Tracheids
Dead cells that taper at the end and overlap one another
Vessels—vessel members (elements) tend to be shorter and wider than tracheids
Continuous tubes of dead cylindrical cells arranged end-to-end
More efficient at transporting water
Xylem
Transpiration – diffusion of water vapor from plant
Phloem
Principal food-conducting tissue in vascular plants
Contains two types of elongated cells
Sieve cells (seedless vascular plants and gymnosperms) and sieve tube members (elements) (angiosperms)
Living cells that contain clusters of pores called sieve areas or sieve plates
Sieve-tube members are more specialized (more efficient)
Associated with companion cells
Roots
Simpler pattern of organization and development than stems Four regions are commonly recognized: Root cap Zone of cell division Zone of elongation Zone of maturation
Casprian strip
strip of wax, that regulates what goees into the cel
pericycle
form secondary roots
Modified Roots
Most plants produce either/or:
Taproot system – single large root with small branch roots
Fibrous root system – many small roots of similar diameter
Some plants, however, produce modified roots with specific functions
Adventitious roots arise from any place other than the plant’s root
Stems
Like roots, stems contain the three types of plant tissue
Also undergo growth from cell division in apical and lateral stems
Shoot apical meristem initiates stem tissue and intermittently produces primordia
Develop into leaves, other shoots, and even flowers
Node – point of attachment of leaf to stem
Internode – area of stem between two nodes
Blade – flattened part of leaf
Petiole – stalk of leaf
Axil – angle between petiole/blade and stem
Axillary bud – develops into branches with leaves or may form flowers
Terminal bud – extends the shoot system during the growing season
In woody eudicots, a vascular cambium develops between the primary xylem and phloem
Connects the ring of primary vascular bundles
In monocots, there is no vascular cambium – no secondary growth
Rings in the stump of a tree reveal annual patterns of vascular cambium growth
Cell size depends on growth conditions
In woody eudicots and gymnosperms, the cork cambium arises in the outer cortex
Produces boxlike cork cells on outside and parenchyma-like phelloderm cells on inside
Collectively called the periderm
Cork cells contain suberin–waterproofing
Periderm – cork cambium, cork, and phelloderm
Forms outer bark—suberized cells
Lenticels – Cork cambium produces unsuberized cells that permit gas exchange to continue
Bulbs – swollen underground stems, consisting of fleshy leaves
Corms – superficially resemble bulbs, but have no fleshy leaves
Rhizomes – horizontal underground stems, with adventitious roots
Runners and stolons – horizontal stems with long internodes that grow along the surface of the ground
Tubers – swollen tips of rhizomes that contain carbohydrates
Tendrils – twine around supports and aid in climbing
Cladophylls – flattened photosynthetic stems resembling leaves
Leaves
Initiated as primordia by the apical meristems
Principal site of photosynthesis
2 different morphological groups
Microphyll
Leaf with one vein branching from the vascular cylinder
of the stem and not extending the full length of the leaf
Phylum Lycophyta
Megaphylls
Several to many veins
Most plants
Most eudicot leaves have a flattened blade
Slender stalk called petiole
Leaf flattening increases photosynthetic surface
Leaves may have stipules
Outgrowths at base of petiole
May be leaf-forming or modified as spines
Veins
Vascular bundles in leaves
main veins are parallel in most monocot leaves
Veins of eudicots form an often intricate network
Simple leaves contain undivided blades
May have teeth, indentations, or lobes
Compound leaves have blades that are divided into leaflets
The leaf’s surface is covered by transparent epidermal cells
Most have no chloroplasts
Epidermis has a waxy cuticle—prevents drying out
Different types of glands and trichomes may be present
Lower epidermis contains numerous stomata flanked by guard cells
Most eudicot leaves have 2 types of mesophyll
Palisade mesophyll – usually two rows of tightly packed chlorenchyma cells—primary site of photosynthesis
Spongy mesophyll – loosely arranged cells with many air spaces in between
Function in gas exchange and water vapor exit
Monocot leaves – mesophyll is usually not differentiated into palisade/spongy layers
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Modified Leaves
Floral leaves (bracts) – surround true flowers and behave as showy petals Spines – reduce water loss and may deter predators Reproductive leaves – plantlets capable of growing independently into full-sized
Shade leaves – larger in surface area but with less mesophyll than sun-lit leaves
Insectivorous leaves – trap insects
Pitcher plants have cone-shaped leaves that accumulate rainwater
Sundews have glands that secrete sticky mucilage
Venus flytrap have hinged leaves that snap shut
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