3. Habitat
• Distributed world wide
• Grows in shady and moist areas of
tropical and temperate regions
• About 200 species, and in Pakistan 3
common species are found in
Himalayas
1. Anthoceros himalayensis
2. Anthoceros erectus
3. Anthoceros chambensis
4. Vegetative morphology
Thallus
• The plant body is gametophyte and
consist of small, dark green, prostrate
thallus
• It is rosette like, and with lobes of
whose margins are divided into small
lobed segments
• Dichotomous system is present
• Surface of thallus is smooth, velvety ,
and contains ridges and spines
• Numerous thread like rhizoids are
present on ventral surface of thallus
6. Internal structure of thallus
• There is no internal differentiation
• Parenchymatous cells are present
• Each contain single lens shaped
chloroplast
• Deep cells contain 2-8 chloroplasts
• Each chloroplast contains single
pyrenoid
• There are two surfaces, upper and
lower epidermis
• Lower epidermis contains mucilaginous
cavities that opens through a pore
called slime pore
• In these cavities blue green alga
resides.
9. Vegetative reproduction
1. Death of older plants: Vegetative reproduction takes
place by the death of older parts. Younger parts
form new thallus.
2. Tuber: Some thallus forms tubers. These tubers are
rich in stored fats and proteins. These tubers
germinate to on the margin of the lobes. They can
survive long periods of drought. Tuber detach and
from new plants.
10. Vegetative reproduction
1. Gemmae: Gemma are also produced
on short stalks on the upper surface of
the thallus. These are also act as
vegetative reproductive bodies.
2. Persistent apices : in some species the
thallus dies except the apices , there
are called persistent apices , they
remain buried in soil and develop into
new plant body during favorable
conditions
12. Antheridia
Antheridia develops on cavities called antheridia
chamber
Present on the dorsal surface
1 to 25 antheridia may develop in each antheridial
chambers
Mature antheridium consist of an ovoid body with
stalk.
There is a mass of spermatogenous cells
surrounded by jacket of sterile cells
14. Dehiscence:
At maturity, the roof of the antheridial
chamber ruptures, exposing the
antheridia. The apical cell of the
antheridial wall, on absorbing water,
ruptures by apical aperture. The
antherozoids are now liberated to the
covering film of water.
The antherozoids:
The antherozoid is spindle like and
biciliate. The cilia are attached to the
anterior end of the body. Sometimes
just near the attaching point of the
flagella to the body, the blepharoplasty
( flagellated cell or basal body) is visible.
The antherozoids swim in the water by
the lashing moment of their flagella.
15. Archegonium
• Archegonia are produced
close to the growing point.
Archegonia are embedded
in the tissue of the thallus.
• Each archegonium
consists of an egg and a
ventral canal cell four neck
canal cells. The canal of
the archegonium is closed
at the top by four cover
cells.
• These cells project slightly
above the general surface
of the thallus.
Development of
Archegonium
16. Fertilization:
• Water is essential for fertilization. In the
mature archegonium, the venter canal cell,
neck canal cells disintegrate and form a
mucilaginous mass.
• It absorbs water, swells up and becomes out
of the archegonial neck by pushing the cover
cells apart.
• This mucilaginous mass becomes continuous
with the mucilage mound and in this way an
open passage down to egg is formed.
17. Fertilization
The mucilaginous mass consists of
chemical substances.
Many antherozoids caught in the
mucilage enter in the archegonial
neck because of the chemotactic
response, reach up to the egg,
and fertilization is effected. Prior
to fertilization, egg enlarges and
fills the cavity of the venter.
Fusion of both male and female
nuclei results in the formation of
diploid zygote or oospore.
Fertilization ends the
gametophytic phase.
18. Sporophyte
The sporophyte of Anthoceros has certain
unique features.
Sporogonium is borne on the gametophyte.
But mature sporogonium does not totally
dependent on the gametophyte.
The mature sporophyte consist a bulbous
foot and a smooth, slender, erect, cylindrical,
structure called capsule. Capsule varies in
length from two to fifteen centimeter in
different species. The Sporogonium appears
like a ‘bristle’ or ‘horn’, hence, the species
are called ‘hornworts
It has following parts
1: foot
2: seta
3: capsule
19. Structure of sporophyte
The Foot:
It is the basal part of the sporophyte which is a
rounded bulbous structure deeply embedded in
the tissue of the thallus .
The lowermost cells of the foot are haustorial
which absorb water and mineral nutrients from
the gametophyte for the developing
sporophyte.
20. Meristematic zone
The Intermediate Meristematic Zone:
This is a narrow zone of meristematic cells located
in-between the foot and the capsule .
It regenerates the capsule from the base, thus the
capsules are always in different stages of growth.
21. Capsule
The Capsule:
The capsule forms the major and conspicuous part
of the sporophyte.
It is a slender smooth upright cylindrical structure
that slightly tapers at the apex.
It consists of
1. capsule wall,
2. sporogenous tissue
3. collumela
22. Capsule Wall:
The capsule wall is made up of 4-6 layers of
parenchymatous cells. The cells of the outermost layer,
which form the epidermis, are heavily cutinised,
vertically elongated and interrupted by the stomata.
Below the epidermal layer is the green parenchyma-
tous, photosynthetic tissue containing chloroplasts.
Thus, the sporophyte is capable of manufacturing their
own food by photosynthesis, except for the water and
minerals for which it depends upon the gametophyte.
23. Sporogenous Tissue
The sporogenous tissue (archesporium) of
Anthoceros is
situated in between the jacket and the
collumela.
At maturity it differentiates into
1. spore mother cells
2. pseudoelaters.
24. Collumela
Collumela: the central part of capsule is
collumela. It contains 4 rows of elongated
vertical cells.
But layer it becomes 16 rows of cells
In transverse section, the columella appears to
be a solid square.
The columella provides mechanical support to
the capsule.
It also helps the spores to disperse and is
associated with the conduction of water and
minerals.
25. Dehiscence of the Capsule:
At maturity, the tip of the capsule loses water. In fact, the
loss of water from the capsule walls greatly favors the
dehiscence.
After drying of the capsule, a slit appears just below the
tip which gradually widens downwards and eventually
the capsule wall splits into two to four valves.
The hygroscopic ( to absorb moisture) movement of the
pseudoelaters releases the spores to a distance by air
current and at this stage the apical portion of the
capsule looks twisted.
The tip of the collumela projects out like a flagellum.
