Marchantia
a. Morphology of Thallus
b. W.M. rhizoids and scales
c. V.S. thallus through gemma cup
d. W.M. gemmae
Permanent Slides
a. V.S. antheridiophore
b. V.S. archegoniophore
c. L.S. sporophyte
Classification
Division-Bryophyta. (1) True roots absent and instead are
present rhizoids, (2) No true vascular strand.
Class-Hepaticopsida. (1) Mostly thalloid, (2) Rhizoids without
septa, (3) Chloroplasts without pyrenoids, (4) Columella
absent from capsule.
Order-Marchantiales. (1) Scales present, (2) Two types of
rhizoids.
Family-Marchantiaceae. (1) Sex organs borne on stalked
receptacles, (2) Air pores barrel-shaped, (3) Elaters in capsule.
Genus-Marchantia. (1) Assimilatory filaments branched, (2)
Scales ligulate and appendiculate both, (3) Gemma cup not
crescent-shaped.
• Cosmopolitan in distribution.
• Genus Marchantia has 65 species ww.
• Grows best in cool, moist and shady places.
• Marchantia polymorpha grows as a pioneer in the
burnt forest soil after fire.
• 11 species in India, growing mainly in the Himalayas
and the South-Indian hills.
• Marchantia palmate : eastern Himalayas. Reproductive
phase during February & March in the Hiamalayas and
during October-November in South Indian hills.
A. VEGETATIVE STRUCTURE:
1. Morphology / External Structures:
• The vegetative plant represents the gametophytic plant
body.
• Prostrate, dorsiventral and dichotomously branched
thallus.
• Distinct midrib, marked on the dorsal surface by a
shallow groove.
• Ventral: Rhizoids and Scales
• Rhizoids hyaline () and unicellular.
• Scales are multicellular & violet in colour. (anthocyanin
pigments).
• Gemma Cups: contain specialized, multicellular, asexual
reproductive bodies/granules called Gemma
2. Anatomy / Internal Structures:
i. Epidermal Region:
Outermost region: upper and lower
Numerous air pores analogous to the
stomata in higher plants;
Rhizoids and scales on lower epidermis.
ii. Photosynthetic Region:
Just beneath the upper epidermis.
Simple or branched photosynthetic filament s.
Composed of Chlorophyll containing cells.
iii. Storage Region: .
Just below the photosynthetic region.
Compact zone of several layers of polygonal
parenchymatous cells.
Achlorophyllous without intercellular spaces.
Mostly contain starch or protein granules,
mucilage and oil.
1. Outline is goblet-shaped with an outer wall and central cavity.
2. The outer wall shows outer photosynthetic region and inner storage
region.
3. The internal structure of photosynthetic region and storage region is
similar to that of thallus.
4. From the floor of the central cavity arise numerous discoid gemmae.
5. Intermingled with gemmae are many mucilage hairs or cells.
6. The gemma cup arises as a part of the thallus. It remains attached
with the thallus by its base.
7. Gemmae is one-celled, stalked structure. The stalk keeps gemma
attached to the base of the gemma cup.
8. The discifonn gemma has two shallow notches on both the lateral
sides. Each notch possesses a row of apical cells.
9. Towards the periphery of the gemma colourless oil cells are present.
Inner to them are the rhizoidal cells.
10. All the cells of gemma except the oil cells and rhizoidal cells contain
chloroplast.
B. REPRODUCTIVE STRUCTURES:
1. External Structures:
The main thallus represents the Gametophyte.
It reproduces sexually through gametes.
Marchantia is heterothallic or dioecious.
Gametophores develop at the distal end of respective thallus (apical
notch)
Antheridia: on Antheridiophore.
Archegonia: on Archegoniophore.
They are terminal.
Marchantia. Disc of archegoniophore as seen
from lower side.
2. Internal Structures:
Ontogenically, the gametophores are the extension of the vegetative thallus.
Therefore, they show the characteristics of the vegetative thallus, i.e., their anatomy
shows the presence of air chambers, air pores and photosynthetic filaments all over the
upper epidermis and storage region just beneath them.
• i. Antheridia:
The air chambers on the upper surface are alternated with numerous
flask-shaped cavities, called the Antheridial Chambers.
The antheridial chambers open externally by a pore, called Ostiole.
Each antheridial chamber contains a single Antheridium.
The mature antheridium is a globular structure, attached to the floor of the
antheridial chamber by a multicellular stalk.
The antheridium has a single layered sterile jacket, enclosing a mass of
androcytes, which eventually metamorphose into antherozoids (minute,
rod-like biflagellate male gametes).
ii. Archegonium:
Archegonia are found in uniseriate fertile pockets along the ventral ridges
of radiating discs, near the stalk.
They are enclosed inside a mass of sterile tissue, called Perichaetium.
The mature archegonium is pendant and attached to the ventral ridges of
the radiating disc by a short stalk.
It is an inverted flask-shaped structure, with a basal swollen Venter and an
elongated Neck.
The venter is surrounded by a single layered sterile Jacket and contains
a large egg and a relatively smaller Venter Canal Cell.
The neck consists of 6 vertical rows of cells, called the Neck Cells, which
enclose a narrow canal with 4-8 Neck Canal Cells.
The tip of the neck has a rosette of four
Cover Cells.
Sporophyte of Marchantia
Marchantia. A. L.s. of nearly mature sporophyte. B. Spore. C. An elater.
Sporophyte of Marchantia
Foot
• The basal portion of the sporophyte is the foot. It is multicellular, broad, bulbous
or anchor-shaped.
• The foot is embedded in the tissue of the archegoniophore (female gametophyte)
and consists of parenchymatous cells. It helps in the anchorage of sporophytes
and the absorption of water and nutrients from the gametophyte for the
developing sporophyte.
Seta
• The seta is a slightly enlarged stalk that connects the capsule with the foot. It
contains numerous vertical rows of parenchymatous cells.
• At maturity, due to several transverse divisions, the seta elongates rapidly and
ruptures the calyptra.
Capsule
• The upper part of the sporophyte is the capsule. It is yellow-coloured, with an
oval or spherical structure.
• The capsule has a single-layered wall (sterile jacket wall) that encloses
numerous spores and sterile elaters. It also contains calyptra, perigynium, and
perichaetium, which collectively form a protective covering around the capsule.
Spore
• The spores are haploid, uninucleate, and spherical in shape. They are very
small, 0.012 to 0.03 mm in diameter.
• Each spore remains surrounded by two wall layers: the outermost exospore or
exine, and the innermost endospore or intine. The outermost exine is thick,
smooth, and slightly reticulate, while the innermost intine is thin.
• A tiny mass of granular cytoplasm is present inside the spore wall. It consists of
a single nucleus and some reserve food material.
Dehiscence of the Capsule and Dispersal of Spores
• As the sporophyte matures, the seta elongates rapidly and ruptures the
calyptra. It pushes the mature capsule into the air through the perigynium and
perichaetium.
• Hygroscopic movement in the elaters assists in the dispersal of spores.
• The elaters are hygroscopic. They coil and uncoil with the changes in the
moisture of the surrounding air. In dry weather, elaters lose water and become
coiled. When the atmosphere is wet, they become uncoiled and cause the
jerking action.
• Due to the jerking action, the spore mass loosens. Finally, the spores are
thrown into the air and dispersed by air currents.
