Chapter 2 Flashcards
Meristematic tissues
Cell division or constant growth=meristematic tissue
-primary (apical). Apical meristems
•shoot
•root
•crown (i.e. Turfgrass)
-secondary (lateral). Lateral Meristems
•Vascular Cambium (veins)
•Cork Cambium (bark)
Permanent tissues
-simple (one cell type)
•parenchyma
•sclerenchyma
•collenchyma
-complex (more than one cell) •xylem •phloem •epidermis •cork
Primary Growth tissue
Happens in APICAL MERISTEMS
- occurs when length is added to a stem or root due to cell division approximately 1/10 inch from root to shoot tip
- occurs in ALL PLANTS -woody and herbaceous
- vertical “lengthening”= Apical meristems
Secondary growth tissue
- secondary growth tissue happens in lateral meristem tissue
- horizontal growth contributes to the wood in trees or shrubs
- happens only in woody roots and stems
- thickening or widening= Lateral Meristems
Primordia
*waiting for mitosis. Undetermined meristatic tissue.
- Primordia is a group of cells that represents the initial stages in development of a plant organ (plural, primordium)
- On stems, nodes containing leaf and axillary bud primordia form at regular intervals alternating with internodes (space between nodes). Primordia develop later into a leaf & auxiliary bud.
Permanent Meristem Tissues
*arise from apical or lateral meristem
•all initial growth comes from the meristem. BUT some cells differentiate to become either permanent
- simple tissues (parenchyma, sclerenchyma, collenchyma)
- complex tissues. (Xylem, phloem, cork)
3 types of permanent meristem tissue
1) Protoderm(complex) hence “derm”
2) Ground (simple)
3) Procambium (complex)
- each type is responsible for different functions of the plant
- simple tissues are made up of one cell type in a mass. Complex tissues have a mix of cell types
Protoderm (type of permanent meristem tissue). THINK DERM
Complex
Matures to form epidermis
-flattened irregular layer covers roots, shoots and leaves
Some of these epidermal cells specialize to become
- guard cells-help is gas exchange. Found in lower epidermis of leaves
- root hairs-emerge from the epidermal cells just above root tip and help absorptive surface of root
Epidermis
A single layer of cells on exterior of leaves stems, flowers and roots
•exudes a waxy material that reduces water loss
- Leaf epidermis cells may form hair
- root epidermal cells form root hairs
Ground (type of permanent meristem tissue).
Simple
•makes up the pith of stems and roots
*differentiates into cork cambium that makes cork aka bark for woody plants
•Ground tissue is the storage cortex inside of roots
•provides cushioningC support and fill for the plant.
Parenchyma (cell type in plant)
- makes up cortex of stems & roots
- makes up mesophyll layers of leaves, contains chloroplasts
- Always mesophyll
- LIVING CELLS
- Stores starches, oils, water, other sudstancds
•WOUNDS ARE FILLED WITH PARENCHYMA CELLS. PLANT PROVIDES A SEAL TO WOUND
Collenchyma (cell type in plant)
- living cells, dead at maturity
- cell walls thickened with cellulose
- They lack the hardening agent lignin
- often occur just under epidermis and often are found mixed with parenchyma cells to make up cortex
- provides flexible support for herbaceous stems, petioles, & leaves
Sclerenchyma (cell type in plant)
- tough thick walls usually reinforced with the polymer lignin
- normally dead at maturity. The cell walls harden after dying for extra strength=wood
•common in stems or bark, may occur elsewhere (protective function)
•two forms of protective
-sclerids-can protect seeds (peach pit)
-fibers-long thin cells that provide structural support. (Rope)
Procambium (type of permanent meristem)
Complex
THINK VEINS/ VASCULAR
•primary phloem (herbaceous and woody)
•primary xylem (herbaceous and woody)
•Vascular cambium (woody plants only)
*gives rise to lateral meristem which consists of
-secondary phloem
-secondary xylem
•Cambium is found wherever there are veins-leaves, stems and roots.
Function of roots
- Anchor the plant
- absorb water and minerals
- food and storage
- All roots perform similar functions
•angiosperm monocot, angiosperm dicot and gymnosperms roots do have internal structural layouts that differ slightly
