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ROOT SYSTEM
ROOT IS AN underground cylindrical part of the plant which develops from radicle and grows vertically downward into the soil.
characteristics
Roots are cylindrical structures. Root is positively geotropic. Buds and leaves are absent. Root is colourless due to absence of
chlorophyll. Root cap is present over the apex.
Third Chapter Plant OrgansSection One Roots
Organ Ones that are formed by many kinds of
tissues , having certain external shape and inside structure and plant body component of carrying out certain physiological function .(review tissue)
vegetative organ (root ,stem ,leaf) Organ reproductive organ(flower ,fruit ,seed)
Tissue The source similar to the function is the same ,
shape structure and the cell group contacting each other closely is called the tissue.
Vegetative organ : Absorb playing , make and supply the body nutriment function of the plant , making the plant body grow , development with. Including the root , stem , leaf.
Reproductive organ :Play a role in breed the later generation and extend ethnicallying. Including the flower , fruit , seed.
absorb function transportation supportion Physiological function breeding preservation assimilation function
Medicinal value
Radix
Ginseng
Radix
Notoginseng
Radix
Astragali
Radix
Ophiopogonis
Part One Forms and Types of Roots
★Forms of Roots★ Root Types1 Main root and lateral root 2 Normal root and adventitious root
Types of Root system
tap root system and fibrous root system
4 Abnormal root storage root fleshy tap root
root tuber prop root aerial root climbing root water root parasitic root
1. Coniform root 2. columniform ~ 3. pelletly ~
4. Spindly root tuber 5. nubby root tuber
1.Prop root 2.aerial root 3.climbing root 4.5.parasitic root
Part Two Inner Structure of Roots Basic Structure of the Root Tip Root cap Region of Division Region of Elongation Region of Maturation
Basic Structure
of the Root Tip
1.Maturation zone
2.Elongation zone
3.Meristematic zone
4.Root cap
Primary Structure Epidermis
exodermis
Cortex cortex parenchyma endodermis casparian dots
passage cell
Primary Structure of Dicotyledon Radicle
1.Epidermis
2.Cortex
3.Endodermis
4.Pericycle
5.Protoxylem
6.Metaxylem
7.Primary phloem
8.Immature metaxylem
Ⅰ.solid view of endodermis cells ( show casparian strip )
Ⅱ.transverse section view of endodermis cells ( show casparian dots )1.Cortex cell 2.endodermis 3.casparian strip 4.pericycle
Casparian dots or casprian strip
Passage cell
Vascular cylinder pericycle
primary xylem (diarch , triarch ,
tetrarch,hexarch,polyarch,etc)
primary phloem ☆Definition : Exarch: The order of differentiation and maturation of
primary xylem of root is from the outside to inside, and is known as exarch.
Formation of Lateral Root
Transverse section
of horsebean root
1 、 endodermis
2 、 pericycle
Formation of lateral root
Secondary Structure of Roots
①Origin and Activities of the Vascular Cambium
Cambium secondary phloem
secondary xylem
Ⅰ.radicle ( dot and line show beginning place of cambium )
Ⅱ.cambium becomes consecutive tissue
Ⅲ.whole cambium make secondary structure
Ⅳ.cambium becomes a ring
1.Primary xylem 2.primary phloem 3.cambium
4. secondary xylem5.secondary phloem
The transverse section of MaDouLing
Ⅰ. ( 1.phellem 2.phellogen 3.cortex 4starch grain 5.secretory cell)
Ⅱ. ( 1.phloem 2.sieve tube gang 3.cambium 4.ray 5.xylem)
Ⅲ. ( 1.xylem 2.ray)
Secondary structure of root
②Origin and Activities of the Cork Cambium Phellogen phellem phelloderm
Periderm and lenticel1.Origination of phellogen 2.epidermis
3.phellogen 4.phellem 5.phelloderm 6.cortex parenchyma7.supplementary cell
Anomalous Structurethe model sketch of root anomalous structure
Ⅰ.shanglu root
Ⅱ.niuxi root
Ⅲ.chuanniuxi root
Ⅳ.heshouwu root
1.Phellem
2.Cortex
3.Phloem
4.Cambium
5.xylem
Symbiosis PhenomenonRoot Nodule and Mycorrhiza