Plant Anatomy and Physiology

Alternative planes of sectioning

Transverse Sectioning

Cross section, perpendicular to the long axis of the organ

Radial Sectioning

cutting parallel with the long axis of the organ

Tangential Sectioning  

Slicing just the surface of a leaf or bark

Scraping

scraping the surface to break off hairs and trichomes

Peeling

epidermal peels are made by breaking or tearing the structure until a piece of the surface tissue protrudes. The surface tissue is then torn away from the body of the structure and mounted in water for direct observation

Maceration

tissues can be mechanically or chemically teased apart so that individual cells are separated from one another

histological stains

the sections are mounted on slides and artificially colored to enhance detail

IKI stain composition

1 % iodine, 1 % potassium

Sudan 4 or Sudan black composition

saturated ca 0.25% dye in 70% ETOH

Phloroglucinol composition

1-2 % dye in 18% HCL

Phloroglucinol reactions

lignified walls- red

Fast green composition

0.5% dye in 95% ETOH

Fast green reactions

cellulosic cell walls - green

cytoplasm - green

primary cell wall

wall that is formed while a cell is actively growing in size (plasmodesmata)

secondary cell wall

(S1, S2, S3) (lignin) (pits)

what cell wall are plasmodesmata found

primary cell wall

What cell wall are pits found in

secondary cell wall

IKI stain reactions

Starch-blue

cellulosic cell walls-brown

cutin and cork-yellow,

callose- yellow

SUdan 4 or Sudan Black reactions

Suberized cell walls - red

Fats and oils- red

Cutin and waxes- red

Latex and resins - red

middle lamella

pectin

Apical meristem

the core of meristematic cells

Promeristem

the few cells at the central position that ultimately control the meristem, these cells are the least differentiated and give rise to the other cells in the apical meristem

Differentiation 

when a plant cell begins to specialize or show differences compared to Pro meristem cells

The three major transitional meristems

Protoderm

Procambium

Ground meristem

Protoderm

the cell layer that develops into the dermal tissue (epidermis)

Procambium

the cells that develop into the vascular tissue (xylem and phloem)

Ground Meristem

All cells included in the fundamental tissue system.

Parenchyma

Collenchyma

Sclerenchyma

Shoot Apical Meristem

the apical meristem of the leaves and stems

Two types of Shoot apical meristem organization

Cytohistological Zonation

Tunica-corpus layers concept

Cytohistological Zonation

Pro meristem (Central Zone)

Rib Zone (pith region)

Peripheral Zone (form leaves)

Tunica Corpus Layers Concept

Tunica - L1 and L2 (anticlinal divisons)

Corpus- L3 (periclinal divisions)

Leaf Primordia 

lateral outgrowths from the shoot apical meristem dome

Leaf base

the attachment to the stem

Leaf lamina

upper flattened part of the leaf

Root Apical Meristem 

the place of division and differentiation in the roots

Quiescent center

In the root apical meristem, cells divide slower than surrounding cells or do not divide at all