Intro Flashcards
Monocots vs Dicots
-depends on how many “seed leaves” or cotyledons are present in the developing plant
-single leaf: monocot
-two leaves: dicot
Meristematic tissue
-apical
-lateral
-composed of immature cells and are regions of active cell division
-small, have thin walls and dense cytoplasm (few vacuoles if any)
-apical meristems: increase length
-lateral meristems: adds girth. Not all plants have these, but in those with secondary growth. “Tree rings”
Primary meristems
- Protoderm
- Ground meristem
- Procambium
Eventually gives rise to three types of permanent tissues
Protoderm gives rise to
Epidermis in first growth
Cork cambium (in some plants), cork, phelloderm in second growth
Procambium gives rise to
-primary xylem and phloem in first growth
-fasicular cambium->vascular cambium->secondary xylem abd phloem in second growth
Ground meristem gives rise to
-Pith and cortex in first growth
-interfasicula and cork cambium in second growth
Permanent tissues in plants
-surface
-fundamental
-vascular
-epidermis
-periderm
-parenchyma
-collenchyma
-sclerenchyma
-endodermis
-xylem
-phloem
The epidermis holds the cuticle which is….
A layer that provides a waxy, water resistant covering
Parenchyma
Houses chloroplasts in leaves (chlorenchyma)
-found in roots, stems and leaves
-relatively unspecialized
-may take on cell division or undergo specialization and form other cell types
-alive at maturity
-have thin primary walls of cellulose
-Single, large vacuoles surrounded by a peripheral layer of cytoplasm
-loosely packed cells
-in stems and roots, function as storage of carbs, water and nutrients
-provides support
Collenchyma
-Functions in support and flexibility especially in young plants
-alive during most of functional existence
-elongate and thicker walls then parenchyma
-irregular thickening of cellulose deposited on inside
Sclerenchyma and it’s types
-specialized support cells
-more specialized then collenchyma
-at functional maturity, most are dead and very thick
-heavily lignified secondary cell wells give strength to the plant
-the lumen of the cell has been almost obliterated
Types: fibres and sclereids
Endodermis
Fundamental tissue that is the modified innermost layer of the cortex.
-surrounds vascular tissue in roots and less frequently in stems
-has lignin and suberin
-young endodermal cells are similar to parenchyma cells but have a band of thickening on radial and transverse side consisting of lignin and suberin and is called the casparian strip
Vascular tissues
-conductive tissue if derived terrestrial plants
-constitute the majority of photosynthetic biomass in many terrestrial ecosystems
-provide humans with almost all of their cultivated, food producing crops
-movement of water and solutes between roots and leaves
-allows for growth and larger size
Xylem
Vascular tissue that Transports water and dissolved substances UPWARD through tracheids
-forms continuous pathway running through the roots, stems and appendages of stems.
Phloem
Complex tissue that contains conducting cells as well as supportive fibres and parenchyma
Steles and types
Xylem+phloem
-Protostele (circle)
-actinostele (blob)
-Plectostele (scratches)
-siphonsteles (include a pith
-Amphiphloic siphonostele (pith and two phloem layers)
-Dictyostele (random vascular bundles)
-Eusteles (regular vascular bundles
-Atacrostele (vascular bundles in pith)
Phylum names end in
phyta
Class names end in
Opsida
Order names end in
ales
Family names end in
aceae
Latin plural ending changes
-a
-en
-ex or ix
-is
-itis
-on or oan
-um
-us
-ae
-ina
-ices
-es
-itides
-a
-a
-i or es
Non vascular plants are relatively undifferentiated, and the cells are mostly
Parenchyma
All plant tissues can be divided into two major categories:
Meeistematic tissues and permanent tissues
Permanent tissues
Composed of more mature, differentiated cells.
May revert to meristematic activity under certain conditions
Meristems
Cell division becomes restricted largely to certain undifferentiated tissues in localized regions known as meristems
Where are meristematic tissues
Growing tips, roots and stems
Fundamental tissues
Tissues that are neither surface tissues or vascular tissues
Ex: parenchyma cells or pith and cortex, collenchyma cells in the angles of stems and sclerenchyma cells that form sheath on outside of vascular bundles
Schlerenchyma cells are customarily divided into two categories
Fibers and sclereids
Fibres:
-elongated cells with tapered ends
-stronger but less flexible then collenchyma
-common in flax and hemp stems
Sclereids:
-variable shapes
-Unbranched sclereids called stone cells; common in nut shells
-asteiscleteid: star shaped sclereids that are flexible, floating in aquatic plants
Casparian strip
Band of thickening running on transverse and radial ends of endodermis consisting of lignin (for strength) and suberin (water-proofing)
-continuous in each endodermal cells and is not permeable to water
-can regulate water and solutes to pass the cell membranes
Complex tissues
Consist of more than one type of cell
-xylem
-phloem
Flowering plant xylem
Xylem contains tracheids and vessel elements
Xylem contains which fundamental tissues
Parenchyma and sclerenchyma
-especially fibres
-parenchyma are the only living cells in functioning xylem
-cytoplasm and nuclei or tracheids, vessel elements and sclerenchyma cells disintegrate at maturity, leaving the thick cell walls.
-schelenchymal fibres in xylem tissue function as support, particularly at aerial part of plant.
Primary xylem
Formed during primary growth from Procambium and includes protocol em and metaxylem
Protoxylem
-first part of the primary xylem that matures and these cells are usually smaller than the metaxylem
Metaxylem
Develops after the protoxylem, but before secondary xylem. Has larger vessels and tracheids.
Tracheids of primary xylem
-stretched during lengthwise growth which causes their secondary walls to be formed in rings or spirals.
Secondary walls of secondary xylem develop after
All length-wise growth has ceased in that organ. Therefore secondary walls are more continuous, and tracheids are connected to one another by numerous pits
Pits location
Pits occur anywhere in the cell wall but they are often particularly numerous on the tapered end of the cell where it abuts with the adjacent cell.
Water and dissolved substances move upwards from _____ to _____ through the ____
Tracheid to tracheid
Pits
Vessel elements
Conductive cells that are more highly specialized than tracheids.
-characteristic of flowering plants (anthophyta)
-not in gymnosperms (conifers)
-have pits and perforations along their sides, through which some lateral movement of substances may take place
-materials move upward or downward through their ends.
-ends are perforated or may be entirely open
-vessel elements are stacked one on top of other to form continuous tube.
Vessel
Vertical series of vessel elements
Difference if tracheid and vessel elements
Tracheids have only pits (no perforations) which are thin areas in the cell walls.
Sieve elements
Principle vertical conductive elements in phloem and are arranged in a vertical series to form structures called a sieve tube. These tubes retain their cytoplasm at maturity unlike tracheids and vessels in xylem. However their nuclei disintegrate.
-elongated cells with specialized porous areas in their cell walls called sieve plates
Sieve elements are connected by?
Strands of protoplasm connect the contents of one cells with those of the next through sieve plates. Food materials located in the cytoplasm can move from one cell to the next by cytoplasmic streaming.
Companion cells
Specialized, elongated parenchymatous cells which are closely associated with the sieve elements in most flowering plants. Derived from the same original cell associated sieve element. Mature companion cells retain both their cytoplasm and their nuclei.
-controls its own cytoplasm and cytoplasm of adjoining sieve element
Protosteles
-simplest and most primitive type
-solids core of xylem surrounded by a cylinder of phloem.
-3 configurations of this type:
- Haplostele: xylem core is a solid cylinder
- Actinostele: xylem has radiating cog-like protuberances
- Plectostele: xylem is cylindrical by phloem is inter spread within it.
Siphonostele
Xylem and phloem form concentric cylinders around a central pith. Has two configurations
- Ectophloic siphonostele: phloem is restricted to the outer surface of the xylem
2.Amphiphloic siphonostele (solenostele) phloem is found both external and internal to the xylem cylinder.
Dictyostele
Stele appears as discrete strands or bundles in cross section. Each bundle has a central core of xylem, which in turn is surrounded by a cylinder of phloem and an endodermis.
Eustele
Discrete bundles arranged around a central pith. The xylem usually forms the inner portion of each bundle and the phloem is oriented towards the outside. The bundles are usually arranged in a single ring, occasionally there are two or more rings around the pith.
Atactostele
Shows a scattered arrangement of discrete bundles throughout the stem.
In plant embryos, the radical, epicotyl, and cotyledon are all _____
Meristems
Radical-roots
Epicotyl-stem
Cotyledon-leaves
The epidermis becomes the _____ in secondary growth
Periderm
Fibers
Schlerechyma category that are very Elongated cells with tapered ends
Sclereids
Schlerenchyma shape that are variable
