Bio 101 LABBio 101 LAB

Post lab Discussion

Ex. 6‐10Ex. 6 10

Exercise 6Exercise 6

EpidermisEpidermis

‐ Outermost layer of tissues

Cl l h d d id f i ll l‐ Closely attached; devoid of intercellular spaces

MULTIPLE EPIDERMIS—O: protodermp

HYPODERMIS– O: ground meristem

EpidermisEpidermis

• Ordinary epidermalOrdinary epidermal cells – devoid of intercellular spaces

• Cells with special structure, form or content

• Cells connected with stomata

• Appendages

Stomatal ComplexesStomatal Complexes

Eudicot MonocotEudicot• Anomocytic

Monocot• Type I

• Anisocytic

• Paracytic

• Type II

• Type IIIParacytic

• Diacytic

Type III

• Type IV

• Actinocytic

MONOCOT STOMATATYPE IV= anomocytic

Type IType III

Type IIType IType I

Exercise 9Exercise 9 

Primary tissuesa y t ssues‐ Products of primary meristems

OBSERVE THE TISSUE ORGANIZATION OF STEMS IN PRIMARY GROWTH

Dermal tissue systemGround tissue systemyPith regionVascular systemVascular system

Exercise 10Exercise 10

• Secondary tissuesSecondary tissues

‐ Tissues dervied from vascular cambium and cork cambiumcork cambium

Vascular cambium

• Secondary xylem and secondary phloem (fusiform initials)

• Vascular rays (ray initials) 

• Cork cambium / phellogenCork cambium / phellogen

‐ Cork cells /phellem and secondary cortex/ phellodermphelloderm

SECONDARY VASCULAR TISSUES

a. Axial systemy

b. Radial system

• Conifer rays y(gymnosperms)

‐ One cell wide ( ) h(uniseriate) except with resin ducts

a Ray tracheidsa. Ray tracheidsb. Ray parenchyma

HOMOCELLULAR or HETEROCELLULAR

• Angiosperm rays

‐ 1 to many cell wide

‐ One type of cell: ray parenchyma but varies in shape

a. procumbent

b. upright

HOMO or HETERO

• Name all the secondary tissues and identify:Name all the secondary tissues and identify:

‐Location, function, origin

C i k bi b i idi i l• Correction: cork cambium being unidirectional

• Bark

=  consists of 

a Inner bark – living; secondary phloema. Inner bark  living; secondary phloem

b. outer bark (rhytidome)‐ dead

Ex. 7 LaticifersEx. 7 Laticifers

• Cells or Series of cells containing fluid (latex)Cells or Series of cells containing fluid (latex)

A. Simple/ non articulated‐ single cell

C d/ i l d i f llB. Compound/ articulated‐ series of cell

Latex

Articulated laticiferArticulated laticifer

• Non anastomosingNon anastomosing

‐ Long, cell chains or compound tubes not connected with each other laterallyconnected with each other laterally

• Anastomosing

‐ Form lateral anastomoses (network) with similar chains or tubes forming a reticulum

Non articulated laticiferNon articulated laticifer

• UnbranchedUnbranched

h d• Branched

‐

LatexLatex

• Clear (Nerium oleander, Araceae)C ea ( e u o ea de , aceae)• Milky (Euphorbia, Ficus)• Contents: CHO, organic acids, salts, sterols, fatsContents: CHO, organic acids, salts, sterols, fats and mucilages

• Terpenoids (rubber), cardiac glycosides,  alkaloids p ( ), g y ,(morphine, codeine), sugar, protein

• Starch grains(Euphorbiaceae, Apocynaceae)• Crystals• Enzymes (papain, cellulase, pectinase etc)

Function of laticifersFunction of laticifers

• Food conduction?Food conduction?

• Food storage?

bb b li ill• Rubber– a metabolic overspill

• Sequester toxic secondary metabolites—protection against herbivores