This lectures on the principals of plants anatomy for level 1 of biology students

1. Plant Anatomy
First stage
Lecture 2
By
Asst. prof. Dr. Luma H. Abdulqadir

2. Plant growth
Meristems - actively growing regions of plant
Primary meristems
Root apical meristems and Shoot apical meristems
Meristems activity:-
cell division-
cell elongation-
cell differentiation

3. Cell differentiationResults in different cell and tissue types
Epidermal cell-
outer layer of all plant organs- in land plants, protected by
outer cuticle- cuticle helps to prevent dessication.
parenchyma• - living at maturity• - involved in metabolic reactions.
Collenchyma
cells living.
elongate.
cell walls unevenly thickened, rich in pectins [pectin - complex polysaccaride,mainly
of galacturonic acid units]
functions in structural support(while stem is still elongating).

4. sclerenchyma- cells dead at maturity-
thick, secondary, lignified cell walls- functions in structural support.
2 cell types:
fibers - very long, thin, tapered.
sclereids - variable in shape, mostly isodiametric.
Xylem
function: conduction of water and minerals.
consists of:– parevesselsnchyma– fibers– tracheary elements.
2 types: tracheids and vessels. actual conductive cells dead at
maturity joined end to end, form pipe-like conduits lignified
secondary cell walls with pits.

5. phloem
function: conduction of sugars.
consists of:parenchyma fibers sieve elements.
2 types: sieve cells or sieve tube members.
actual sugar-conductive cells- semi-live at maturity (lose
nuclei, but have cytoplasm).
primary cell-wall only- have callose-lined pores (making up a
sieve plate or sieve area), through which sugar solution passes

7. Classification of Meristems
1- Based on origion

9. 2- Based on position:
Apical meristem
The meristems which occur at the tips of roots and shoots and
produce primary tissues are called apical meristems.
Root apical meristem occupies the tip of a root while the shoot
apical meristem occupies the tip of the stem axis.
Intercalary meristem
The meristem which occurs between mature tissues is known as
intercalary meristem.

10. They occur in grasses and regenerate parts removed by the grazing
herbivores.
Lateral meristem
Meristems present at the sides of the plant organs are called lateral
meristems.
E.g., Fascicular cambium, Interfascicular cambium and Cork
cambium.
Responsible for producing the secondary tissues.