IT IS A DESCRIPTIVE PRESENTATION ON TYPES OF SPORES AND SPORANGIA FOUND IN PTERIDOPHYTES

1. TYPES OF SPORANGIA
AND SPORES IN
PTTERIDOPHYTES
Submitted & Presented by-
Shreyasi Dey
Roll No.08, 2nd Semester
Department-Botany, N.B.U

2. BRIEF HIGHLIGHTS
• Sporangium-the spore case
• Orientation
• Variety through modification
• Evolution through Variation
• Principal types of sporangium
• KEY Features
• Development pattern
• Affinities of Protoleptosporangium
• Gender of sporangium
• Spores variety
• Gender Inequality
• Spore- The unit of Reproduction

3. SPORANGIUM-The Spore Case
• Vascular cryptogams are an assemblage of seedless
vascular plants that have successfully invaded the
land and reproduce by means of spores.
• It is an enclosure in which spores are formed
• Can be composed of a single cell or can be
multicellular
• Most primitive sporangial types are stalk less, or
sessile. If a stalk is present at all, it is merely a
slightly raised multicellular area at the base of the
sporangial capsule.
• The trend in sporangial evolution is evidently from
solitary large capsules to increasingly elaborate
groupings of smaller sporangia.

4. ORIENTATION
• The leaves in most of filicophyta serve a dual purpose
of photosynthesis and reproduction.
• In the common ferns like Adiantum, Pteris ,Dryopteris
any leaf or leaflet can bear sori on its under surface.
• There is no distinction between fertile and sterile
leaves
• There are however some ferns that exhibit segregation
of photosynthetic and reproductive function.
• Their position vary in different groups, viz.
• Cauline –Psilotum, Rhynia; Adaxial Leaf surface-
Lycopodium, Selaginella; Leaf axil- Ophioglossum

5. VARIETYTHROUGHMODIFICATION
SYANANGIUM: a group of FUSED sporangia in which spores develop
SPIKE: sporangia borne on an outgrowth-The fertile SPIKE projecting from the
adaxial leaf surface. Sporangia found on the margins of spike
SPOROPHYLL: sporangia containing fertile leaves
STROBILUS: sporophylls grouped in definite areas
SORUS: sporangia are aggregated in clusters. Sporangia and especially sori have traditionally provided the
most important characters for fern classification.
SPOROCARP: sporangia present within specialized structure. Mostly oval or bean shaped biconvex, flattened
structure. It is green and soft when it is young but at maturity it becomes very hard and brown in colour.

6. EVOLUTUON THROUGH VARIATION
Simple Sorus
All sporangia originate and mature at the same time
All sporangia are at the same stage of development
Example- Osmunda, Ophioglossum
Gradatae Sorus
Sporangia develop over a period of time
Mature sporangia at Center and the younger ones at peripheral sides
Example-Marsilea, Cythea
MixedSorus
• Mature and Immature sporangia of Different ages are arranged in
Irregular Fashion
• Exampe- Pteris, Adiantum

7. PRINCIPAL TYPES OF SPORANGIUM
• On the basis of sporangial development they are classified as 3 types.
• The Advanced Leptosporangium and Primitive Eusporangium
• The Transition type- Protoleptosporangium intermediate between the EUSPORANGIAUM and
LEPTOSPORANGIUM
• But they should in no case can be regarded as phylogenetic links between them. They have a
long evolutionary history and were represented in the Permian, the living members of this type
can be regarded as LIVING FOSSILS.

8. KEY FEATURES
Eusporangium
1. Several cells are concerned in its
initiation
2. Mature sporangium has a short and
thick stalk
3. Sporogenous cells are sometimes
cubical
4. Annulus is less developed and is
present on only one side of the
sporangium
5. Number of spores is comparatively
large
6. Presence of cholorophyll in the
spores is sometimes observed.
Leptosporangium
1. Conical shape of sporangial initial
2. Wall is one or two layered
3. Tapetum orogiantes from the outermost
sporogenous cells
4. Presence of a thin walled Stomium
5. The spore case itself is few celled, and
the outer wall is only one cell thick at
maturity.
6. The number of spores produced usually
only 128, 64, or 32, most commonly 64.
7. Most leptosporangia have a bow or
annulus made up of strongly modified,
thickened cells

9. DEVELOPMENT PATTERN
Sporangium develops from GROUP of superficial
cells.
These cells divide periclinally into primary wall
layers and inner primary sporogenous cells.
The outer wall layers form the wall of the
sporangium while inner sporogenous cells divide
meiotically and form spores
Arises from a SINGLE superficial cell
Divides transversely to form an outer and inner
cell. While inner cell forms the stalk, the entire
sporangium develops from outer cell.
Sporogenous tissue divides meiotically to give rise
to HAPLOID spores

10. AFFINITIES OF PROTOLEPTOSPORANGIUM
Similarities with Eusporangium
• 1. Large number of spores
are produced .Sporangia
massive and not arranged in
distinct sori.
• 2. Structure and
development of the
archegonium
• 3. Antheridia large in size and
have many wall cells and
produce many spermatozoids
• 4. Internal structure of the
petiole. Presence of stipule like
expansions at the base of
petiole
Similarities with Leptosporangium
• 1. Origin of tapetum from the
archesporial cells
• 2. Presence of a primitive type of
annulus in the sporangia
• 3. Presence of a thin walled
tapetum
• 4. Wall of archegonium is single
layered
• 5. Antheridia and archegoinia are
of projecting type
• 6. The prothallus lack endophytic
fungus and is of cordate type
• 7. Embryo development is of prone
type i.e the first division of zygote is
vertical

11. GENDER OF THE SPORANGIUM
• Depending on the gender of spore content,
Sporangium is 2 types-
• Microsporangium and Megasporangium
a) Microsporangium- it is the producer of microspores which are small
spores, numerous in number and give rise to male gametophyte
b) Megasporangium- produces big spore called megaspores, fewer in number
and give rise to female gametophyte
• Depending on the type of spores, Sporangium is –
• either Homosporous or Heterosporous
a) Homosporous-all spores are alike.
• In homosporous Pteridophytes prothalli are monoecious
a) Heterosporous- micro and megaspores are produced separately.
• In heterosporous species prothalli are always dioecious.

12. SPORES VARIETY
Depending on the presence of chlorophyll-
Green/Chlorophyllous and Non green/Non chlorophyllous
Green Spores
• First, they exhibit a clear tendency to a quick
germination, which is in mean of 1.5 days.
• Second, their germination ability is very rapidly lost,
with a mean viability of around 48 days.
• Green spores, in a state of active respiration with a
higher water content and with chlorophyll present in
an active state, can germinate almost immediately
after sowing.
• Do not enter into a period of dormancy characteristic
of non-green spores.
• The constant physiological activity of the green spore
utilizes the storage compounds in an apparently
short period of time.
• As the storage compounds are totally used up, the
spores become non-viable. Water loss may also play a
part in reducing the length of viability in green spores.
Non-Green Spores
• Great majority of ferns have non-green spores, i.e., which are
without evident chloroplasts at the time of dissemination.
These spores do possess proplastids.
• The length of time between sowing and germination in non-
green spores is variable, from four to six days or even to 210
days
• Must absorb additional water and produce chloroplastids
from proplastids before germinating.
• This difference in activity would account for the differences in
germination rate
• In contrast to green spores, non-green spores remain viable
for extremely long periods, up to 48 years in Asplenium.
• The absolute record to date of spore viability is reported
within the heterosporous genus Marsilea: megaspores
obtained from 100-year-old sporocarps of M. oligospora
germinated forming rhizoids and archegonia (Johnson 1985).

13. GENDER INEQUALITY
• The gender of a pteridophyte is based on the
spore
• Microspore ensures the Male plant body as
after fertilisation it produces the Male
Gametophyte only
• On the other hand Megaspore is the Female
spore which gives rise to Female Gametophyte
• DEVELOPMENT PATTERN

14. SPORES : THE UNIT OF REPRODUCTION

15. THANK YOU