2. CLASSIFICATION
Division : Filicophyta
Class : Leptosporangiopsida
Order : Filicales
Family : Polipodiaceae
3. DISTRIBUTION
It is a cosmopolitan fern distributed almost all geographical region.
It is represented by about 250 species that grown abundantly in the
tropical and sub tropical regions of the world.
Common species in India : P.vitata , P. cretica L, P.stenophylla wall, P.
wallichiana etc.
4. HABITAT
It is usually grown in well drained places or crevices of rocks.
It is common along slopes of hills and seen 1200m above sea level.
They are a terrestrial genus inhabiting shady and moist forests and hilly areas.
5. Morphology
The main sporophytic plant body is differentiated into,
- Root
- Rhizomatous stem
- Leaves
6. ROOTS
Roots are black, slender and wiry arising from the underside of the Rhizome.
The primary root is ephemeral, and is replaced by a large number of adventitious roots
developed all over the surface of the rhizome.
The roots are small and branched.
7. RHIZOMATOUS STEM
The rhizome or stem may be creeping (P. grandiflora) or erect (P. cretica, P. vittata) which may or
may not show branching.
The rhizome is differentiated into nodes and internodes and its entire surface is covered with
scales.
The growing point of rhizome is covered with ramenta.
8. LEAVES
The leaves are borne on the upper surface of the Rhizome.
Leaflet is rough, has a midrib from which lateral veins with dichotomous branching
arise. Venation is open dichotomous venation.
When young the leaves are spirally coiled and show circunate vernation that is typical
of true ferns.
The leaves are unipinnately or multipinnately compound or decompound with a long
rachis.
Developed leaves are called fronds.
9. Petiole is covered with scales and hairs
The pinnae are sessile. The pinnae are small near the base as well
as towards the apex, while they are large towards the middle.
Leaf apex is occupied by an odd leaflet.
Leaflet is rough, has a midrib from which lateral veins with
dichotomous branching arise. Venation is open dichotomous
venation.
Each pinna is transversed by a central midrib which gives off lateral
veins that bifurcate near the tip.
10.
11. Leaf bears reproductive structures called sori, along the ventral margin of their pinnae.
Sori are continuous along the margin , except the apices.
13. 1. Rhizome
Rhizome is differentiated into epidermis, cortex and stele.
Epidermis
Single layered and invested with a hard and protective cuticle around.
In some growing young parts, it may be covered by ramentum.
Cortex
Multilayered
It forms main bulk of the Rhizome .
14. It is differentiated into,
1. Outer cortex
2. Inner cortex
Outer cortex is sclerenchymatous and it forms the hypodermis.
Inner cortex is parenchymatous.
Endodermis is uniseriate
15.
16. Stele
Stelar organization of the Rhizome varies with species.
- Solenostelic
- Dictyostelic
A stele in which the protostele is medullated or with pith at the centre is
Known as siphonostele.
In siphonostele , pith is found with one leaf gap.
Siphonostele that is broken into a network of separate vascular strands are
called dictyostele. This breaking is due to the presence of large number of
leaf gaps.
Each separate vascular strands is called meristele.
17. Stele
Stele consists of number of meristeles usually arranged in two rings inner and outer.
Meristele is embedded in the parenchymatous ground tissue.
Each meristele is elliptical with single layered endodermis having casparian strips in its radial walls.
1- 2 layered thin walled pericycle is present below the epidermis and surrounding the phloem.
Phloem has only sieve cells and phloem parenchyma. It completely surrounds the xylem.
Xylem is present at the centre of the meristele. It shows central protoxylem surrounded on either side by
metaxylem.
18. 2. ANATOMY OF PETIOLE
It is differentiated into epidermis, ground tissue and vascular bundle.
Epidermis
Single layered with narrow quandrangular cells covered by thick cuticle.
Some epidermal cells give rise uniseriate bicellular hairs called as ramenda
Ground tissue
It has multi layer sclerenchymatous hypodermis followed by parenchymatous tissue in which the vascular bundle is
empeded.
19.
20. Vascular bundles
It is ‘ V’ or ‘ U’ shaped
It resembles meristele and has single layered endodermis with casparian strips.
Pericycle is 1 or 2 layered and parenchymatous.
Xylem is at the centre with mesarch condition surrounded by phloem.
21. ANATOMY OF LEAF
Anatomically leaves has three main parts namely upper epidermis , lower
epidermis and mesophyll.
Epidermis
The cells of the upper epidermis are large with thick outer walls while those of the
lower epidermis are small and thin walled.
Stomata are restricted to the lower epidermis.
Mesophyll
It is either homogeneous or differentiated into upper pallisade and lower spongy
with broader intercellular spaces.
22. Midrib region has a single concentric type of vascular strand with the distinct
endodermis.
Bundle sheet extensions are prominent and they occur as groups of thick wall
the cells below the upper and above the lower epidermis.
Palisade and spongy tissues are absent around the midrib
23.
24. ANATOMY OF ROOT
Root has 4 main anatomical parts namely epidermis, cortex, endodermis and stele.
Epidermis
It is single layered with thin walled cells.
A few cells form root hairs
Cortex
It is multilayered and differentiated into paranchymatous outer cortex,
sclerenchymatous inner cortex and single layered endodermis with casparian
thichenings
Endodermis is single layered.
25. Stele
It has single layered thin walled pericycle
Exarch or diarch xylem
Protostele
28. VEGETATIVE REPRODUCTION
Death and decay of older portion of Rhizome.
When did decay reaches the branching regions the two branches separate and
grow us individual plants.
29. SPORE PRODUCING ORGAN
Pteris is a homosporous fern
The sorus of pteris is called coenosorus.
Coenosorus are marginal , born continuously on
sporophyll margins.
30. The coenosori are protected by the reflexed margin ( the false
indusium) of pinnae.
Sori are intermingled with many sterile hairs in between the
sporangia
31. Structure of a mature sporangium
A mature sporangium has a long stalk that terminates
in a capsule.
The jacket or wall of the capsule is single layered but
with three different types of cells.
32. 1. A thick walled vertical annulus
incompletely overarches the
sporangium.
2. A thin walled radially arranged
stomium.
3. Large parenchymatous cells with
undulated walls.
33. The sporangium dehisces transversely along the stomium due to
the shrinkage of annular cells
The spores are dispersed through air to a moderate distance.
34. The capsule contains many spores. All spores are structurally and functionally alike ; hence pteris
is a homosporous pteridophyte.
Spores are triangular in shape with the trilete aperture, bounded by two walls , exine is variously
ornamented.
The spores germinate after falling on a suitable subtractum. Initially the spore wall ruptures and the
inner contents come out in the form of a germ tube and subsequently by a transverse division in
the germ tube forms the first prothallial cell. From that the complete gameatophyte is orginated.
35. GAMETOPHYTE
Green , heart shaped with many rhizoids on the under side for
the absorption.
The prothallus is made up of parenchymatous cells which are
single celled thick towards the margin and many celled thick
towards the centre
The growing point are located in the apical notch.
The prothallus is monoecious.
Antheridia appear first and are confined to the basal central or
lateral regions among the rhizoids
Archegonia develop near the apical notch.
36. ANTHERIDIUM
A mature antheridium consists of two ring cells, one or two cover cells and a
central mass of coiled and multinucleate antherozoids.
The antheridium at the maturity absorbs water and swells.
Due to the increase in pressure within the antheridium the cover cells split apart
releasing the antherozoids in a thin film of water present on the surface of the
prothallus.
37. ARCHEGONIUM
It consists of a swollen base called Venter and a
projecting short and slender neck.
A mature archegonium of pteris consists of a 5-6 celled
projecting curved neck , a neck canal cell, a ventral canal
cell and an egg.
38. FERTILIZATION
At this time the ventral canal cell, the neck canal cell and the neck cell at the top
disintegrate forming an open passage for the antherozoids to come towards the
egg and eventually one of the antherozoids fuses with the egg to form the zygote.
39. New sporophyte ( Embryo)
In pteris the first division of zygote is vertical followed by a second transverse
division resulting in the formation of a quadrant. Further a 32 celled embryo is
formed due to further divisions of the quadrant.
The differentiation of embryo begins at this 32 celled stage. No suspensor is formed
the hypobasal cells form stem apex and foot, while epibasal cells form cotyledon and
root.
