5. Both living and fossil forms
Members intermediate between eusporangiopsida and leptosporangiopsida
6. Resemblance with eusporangiate ferns
Eusporangiate development of sporangia
Massive sporangia wiyh large number of spores
Antheridia has many wall layers and produce
many antherozoids
Prothallus- thick, massive and long lived
Indistinct endodermis, presence of mucilage
canals near vascular bundles
Presence of stipule at the base of petiole
7. Resemblance with leptosporangiate
ferns
Tapetum originate from archesporial cells
Primitive type annulus
Thin walled stomium
Sporangial wall single layered
Projecting type antheridia and archegonia
Prothalus lack endophytic fungus and is of cordate type
Prone type embryo development- first division of
zygote vertical
8. Osmunda
Wide distribution- tropical and temperate
12-14 sps
In India- 5 sps- O.regalis, O.claytoniana, O.javanica, O.
japonica, O.cinnamomea
Grows in higher altitudes usually
Prefer shaded and cool habitats
Very much restricted in distribution- in isolated patches
9. Morphology
Medium sized ferns
A few- O.cinnamomea- 2-3 meters
Rhizome- wholly subterranean, upright, short, stumpy, sparingly
branched- dichotomous
Rhizome is profusely beset with older leaf bases which are
sclerenchymatous- additional strength to rhizome- are arranged in
close spirals- on entire surface
Near the base of leaves- adventitious roots arise from rhizome
Roots- hard and rough, black or brown, profusely branched and has
brown root hairs below their tips
Rhizome with leaf bases and tufts of roots- may reach a foot or so
in diameter
10. Circinate vernation present
Leaves pinnately compound- unipinnate or bipinnate, length- 2-3 meters
in some sps
Leaf base flattened to form stipule like expansion
Leaflets leathery, variously incised
Older lower leaflets – larger in size and gradually become smaller towards
the distal end- to give a conical appearance
Young leaves covered with unbranched multicellular hairs which fall off at
maturity
Leaves arranged in close spirals and form a basket shaped crown at the top
of rhizome
11. Leaves- monomorhic/dimorphic
Monomorphic-( O.regalis, O.claytoniana) only one type of leaves with
dimorphic pinnae- some pinnule sterile others fertile- segregation of
photosynthetic and fertile functions in the same leaf
Dimorphic- (O.cinnamomea, O.japonica)two types of leaves- sterile leaves
and fertile leaves. Fertle leaves- no green lamina- have only sporangia
directly borne on the branches of rachis
12. Anatomy
Rhizome-
No definite epidermis
Outer cortex- several layers of thick walled cells, outer boundary is irregular
due to persistent leaf bases
Cells are dead and black coloured
Numerous leaf traces present here
Leaf base vascular bundles are also seen
Gives mechanical strength
14. Inner cortex- few layered, thin walled cells fille with starch grains
Some leaf traces are also present
Leaf trace bundle- C shaped, has its own endodermis and 2-3 layered
pericycle
Phloem completely surrounds the central xylem strand
Xylem- horse shoe shaped
Protoxylem in the concave side as small masses
15. Endodermis-
Next to inner cortex- endodermis- has distinct casparian strips
Endodermis- completely surround the stelar region- uninterrupted
Pericycle- 2-3 layerd, parenchymatous next to endodermis
16. Stele – has many C- shaped xylem bundles surrounded by a continuos ring of
phloem elements
Protoxylem lies in the concavity of the xylem bundle
Number of xylem strands varies in different sps
Pith- conspicuous- parenchymatous or a few sclerenchyma strands may be
present
Stele- is said to be dictyoxylic as it can not completely fulfill the conditions of
a dictyostele
17. Petiole
Epidermis- single layered parenchymatous
Has simple multicellular hairs when young
Few layered sclerenchymatous hypodermis
Cortex- broad, parenchymatous
Vascular bundle single, horse shoe/ C shaped
Has a central xylem core surrounded by phloem on all sides
Protoxylem groups- several along the concave side
Metaxylem forms major part of the xylem tissue
Many mucilage canals present towards the concave side of the vascular
bundle
19. Leaflet
Has upper and lower epidermis- parenchymatous
Stomata- on lower epidermis
Mesophyll undifferentiated- has thin walled parenchyma cells with
intercellular spaces of varying dimensions
Cell contain chloroplast
Single concentric vascular bundle is present
20. Root
Endogenous in origin from rhizome
Distinct epidermis in young roots
Later it is replace dby outermost layer of cortex- exodermis
Next to epidermis- a few layered hypodermis of thick walled small cells
Rest of the cortex- parenchymatous
Endodermis- distinct
Pericycle- 2 layered and thin walled
Stele- usually diarch/ in some triarch
22. Two xylem bundles meet at the centre
Protoxylem- exarch
No pith
Phloem- as two patches on either side of the xylem masses
23. Reproduction
Sporophyte- homosporous
Fertile pinna arise as branches of the rachis
Clusters of sporangia are borne on these thinned out
leaflets- known as tassels of sporangia.
In some sps- lower parts of pinna – fertile and distal
parts sterile and photosynthetic
In some. Sterile pinna bear sporangia along the
margins
In O.claytoniana, fertile pinna restricted to the
middle of the leaf
Pinna bear many sporangial clusters- known as tassels
A sporangial tassel corresponds to a section of the
leaflet
Sporangia- naked- not covered by indusia or hairs
26. In O.claytoniana, an abnormal condition
was seen for the sporangia in one study
Some sterile pinnae were seen to possess
sporangia as sori on their abaxial surface-
may be a transition zone between sterile
and fertile pinnae
27. Sporangia
A mature sporangium – massive, short
stalked and pyriform structure
Stalk is many celled and varies in length
Capsule has- single layered jacket cells
Tapetum- 3 layered- do not disorganise to
form plasmodial fluid
But in O.claytoniana, tapetum is plasmodial
Tapetal layer is derived from primary
archesporial cell
Spore mother cells undergo meiosis to form
128-512 haploid spores
30. Mature sporangium develops a
transverse group of thick walled
cells on one side- annulus
A vertical row of thin walled cells
opposite the annulus represents
the line of dehiscence
As the annulus dries and shrinks,
sporangial wall is pulled apart
along the line of dehiscence to
liberate the spores
31. Sporangial development
Sporangia appear as a small protuberance on
the fertlie pinna
In each such protuberance, a single sporangial
initial becomes distinct by its larger size,
distinct nucleus and abundance of cytoplasm
Sorangial initial divides into an outer smaller
cell (primary jacket cell) and inner larger
cell(primary archesporial cell)
primary archesporial cell divides to form 3
peripheral cells enclosing a central primary
sporogenous cell
The 3 peripheral cells divide periclinally and
anticlinally to form the tapetal layers
In some sps the inner layer of tapetum is
derived from the primary sporogenous cell
32. Sporangial stalk is derived
from the surrounding cells
partially or fully – so the
devpt cannot be traced to a
single cell as in
leptosporangiate ferns- so it
is named as
protoleptosporangiate
development
34. Gametophytic generation
Starts with haploid spores
Spores- spherical, has adistinct triradiate mark
Spore wall- outer exine- thick ornamented
Inner- intine- thin
Has a central distinct nucleus surrounded by
cytoplasm and numerous chloroplasts
Remain viable for one week
35. Spore germination
Spore absorbes water, exine ruptures along the
triradiate mark, intine comes out as a small conical
papilla
It divides by transverse wall into primary rhizoidal cell
and large prothallial cell
Rhizoidal cell forms the first rhizoid
Prothallial cell has numerous chloroplast
It grows exactly opposite the first rhizoid- bipolar
germination
In some prothallial cell divides by a few transverse
walls to form a green filament
The terminal cell of the filament divides by two
36. The lower cells of the filament divide longitudinally
apical cell cuts off cells to its right and left sides in an alternate
walls, then each by vertical wall to form an outer cell and inner
cell
Inner cells divide by horizontal walls which add to the thickness
of the midrib
Outer cells divide rapidly, overgrow the apical cell giving the
prothallus a heart-shaped appearance
Apical cell may remain functional for a longer period and cut off
cells laterally and also to the dorsal and ventral sides
Finally an elongate heart shaped prothallus with a distinct cushion
below the notch is formed
Mature prothallus- 3-6 cms long
37. Mature prothallus- elongated, unbranched,
dorsiventral, green and cordate
Length 2-3 cm
Has a distinct midrib
Midrib- thick and cishioned below the notch
Rhizoids- arise from ventral side, usually
unicellular
Monoecious and protandrous, flat, ribbon like and
has smooth/ slightly wavy margin
Sometimes- prothallus may be unisexual
38. Sex organs
Antheridia- projecting type
Terminal/marginal/ even ventral in posotion
Large and globular
Stalk may or may not present
Has a single layered jacket. Jacket cells
contain chloroplast
A triangular opercular cell is present, which
will open to liberate the male gametes.
Spermatozoids- minute, coiled and
multiciliate structure
Has two coils- posterior coil slightly broader
than anterior one
39. Archegonium- produced on ventral side of
prothallus
Has a projecting neck from the median
cushion
Neck has 4 vertical rows of cells, each row
6 cells in height
Neck encloses a single binucleate neck canal
cell
Venter is embedded in the prothallus tissue,
41. Fertilization
Usual process, neck canal cell and ventral
canal cell disorganise and become
mucilaginous
It absorbes water swells up and forces the
apical tier of cells apart, making a passage
for the sperms to enter and fertilization
occurs and zygote (2n) is formed
42. Embryogeny
Dipoid zygote is established
It secretes a thick wall to form the oospore inside
the venter
It divides by a vertcal wall to form 2 equal cells
They divide by another vertical wall right angle to
the first vertical wall to form quadrant stage
the epibasl half form leaf and stem
Hypobasal half form foot and root.
No suspensor- so the development is exoscopic.
44. Quadrants divide to form octant by
another transverse wall formation
Further divisions are irregular
Root initial forms the primary root,
foot is haustorial
Young leaf appears as a conical
protuberance on one side
Stem apex appears on one side of the
leaf apex and grows into an
underground stem after the primary
root and leaf have established
45. Apogamy – from the prothallus the sporophyte
develop as a vegetative outgrowth in some sps
In O.javanica from the sporophytic tissue
production of antheridia has been reported
Economic importance- root and stem fibres
used for orchid cultivation
As ornamentals- for beauty of the foliage
Young leaves used as vegetable by some people