Bryophytes are non-vascular plants that include mosses, liverworts, and hornworts. Riccia is a genus of thallose liverworts commonly found growing terrestrially or aquatically. It has a flat, lobed gametophyte thallus with dichotomous branching and a midrib furrow containing its sexual organs. Riccia reproduces both vegetatively through thallus fragmentation and sexually through the fertilization of archegonia by antheridia-derived sperm. This results in a sporophyte embedded in the gametophyte that produces haploid spores through meiosis. The spores germinate to form new gametophyte plants,

1. Riccia
Bryophytes

2. What are bryophytes
Bryophytes are a group of plants
that include mosses, liverworts and
hornworts.
They are the non-vascular plants.

3. Riccia taxonomic classification
Division Bryophyta
Class Hepaticopsida
Order Marchantiales
Family Ricciaceae
Genus Riccia

4. Habitat and examples
Majority of the members of this genus are terrestrial but some species are aquatic, and
they are forund growing in water.
The following seven species have been commonly reported in
Riccia robusta; R. melanospora; R, cruciata; R. sanguinea,’ R. himalayansis;
R.pathankotensis, Riccia robusta; R sanguinea and R. pathankotensis
These species are found in Punjab plains , river beds, bank of river and canals, and along
the streams

5. Species found in punjab

6. Vegetative structure
( notch, furrow, lobes)
 It is a thalose liverwort.
 The plant body is gametophyte and generally it
appears as rosette because of extensive growth of
thallus lobes. ( it shows repeated dichotomy)
 The thallus grows flat on the ground and each lobe
has a notch at the apex , which has at the growing
point .
 Lobes are thicker in middle and thinner from
margins
 A deep cleft or furrow is present at the mid of each
lobe.
 The sex organs are embedded in this furrow
 In some aquatic species like R. fluitans have narrow
ribbon like furrow having repeated dichotomous
branches .

7. Rhizoids
 Rhizoids are also present on the
ventral surface of the thallus
 The rhizoids are present on the
middle and are of two types
1. Smooth and tuberculate e.g
Marchantia

8. scales
 the scales are also present on
the ventral side
1. In older parts they are arranged
in 2 rows
2. While in younger parts they are
arranged in 1 row.

9. Internal structure of thallus
 It is made up of
parenchymatous cells , that
are bound of upper and lower
epidermis
 There are 2 regions
1. Upper assimilatory region
(photosynthetic region)
2. Lower storage region

10. Upper assimilatory region
 It is made vertical rows of cells
 They are 6 to 8 cells in height and
contain large air spaces
 They are rich in chloroplast and form
photosynthetic tissue
 In the upper epidermis the spaces
work as air pores for exchange of
gases
 Uppermost cells of these vertical rows
of chlorophyll-containing cells remain
devoid of chloroplast and thus form a
hyaline discontinuous layer of upper
epidermis.
 Continuity of the upper epidermis is
broken by many air pores.

11. Lower storage region
1. Lower storage region ( compact
parenchyma cells contain few
chloroplast, mostly colorless) but
rich in starch .
2. Sometime also store water
3. They are without intercellular
spaces
4. They have closely packed
parenchyma cells
5. these lower storage region cells
from scales and rhizoids

12. Transverse section of thallus

14. REPRODUCTION
 multiply vegetatively by the decay or death of
the Older parts which results in the separation of
younger branches, each of which grows into an
independent plant
 In certain species (R. fluitans) small adventitious
lateral branches may be produced from the
ventral side of the thallus, these adventitious
branches on detachment give rise to new plants,
 Formation of vegetative reproductive gemma-like
multicellular bodies at the apices of rhizoids have
also been reported in certain species.

15. SEXUAL REPRODUCTION
 Riccia plants may be monoecious or
dioecious depending upon the species
 Both the male (antheridia) and
female (archegonia) reproductive
organs are produced in acropetalous (
equal) order on the dorsal side of the
thallus in the median furrow.
 In the monoecious species the
antheridia are generally produced
earlier than the archegonia.

16. Antheridium:
Antheridium is present in a cavity on the dorsal surface called antheridial
chamber.
2. Antheridial chamber has a narrow opening or pore on the apical side.
3. A mature antheridium is a stalked, club-shaped or pear-shaped body.
4. Antheridial stalk is multicellular.
5. It remains surrounded by an outermost layer of one- celled thick sterile
jacket.
6. Inside the jacket layer are present many small, cubical androcyte mother
cells.
7. Each androcyte mother cell contains dense cytoplasm and large nucleus. It
divides diagonally into two androcytes.
8. Each androcyte metamorphoses into a single structure, variously called
antherozoid, spermatozoid or sperm.
9. Each antherozoid is a minute, uninucleate body containing two long flagella
at its anterior end.
10. Lower flagellum is slightly larger than upper one.
11. Dehiscence of antheridium takes place in the presence of water.

17. Archegonium:
 The archegonium remains embedded in the archegonial cavity
on the dorsal surface of the gametophyte.
 Upper part of the neck of archegonium generally protrudes out
of the cavity.
 An archegonium is a flask-shaped structure made up of a long,
elongated neck and a globular venter.
 Venter is sessile and surrounded by a one-celled thick layer,
made up of 12 to 20 cells.
 Neck consists of 4 to 6 neck canal cells, and remains surrounded
by six vertical rows of cells.
 Each longitudinal row consists of 6 to 9 cells.
 At the tip of the neck are present four cover cells or lid cells.
 Venter contains an upper, small ventral canal cell and a lower,
large egg cell.
 At the time of fertilization all the cells, except the egg,
disintegrate and form a mucilaginous liquid, which gives entry to
the spermatozoids. The ultimate product of the fertilization is
zygote.
 The ultimate product of the fertilization is zygote.

18. Archegonia

19. Sporogonium:
 It is simple and made up of only capsule or
spore-sac
 Foot and seta are absent.
 It remains embedded in the gametophyte,
and it is a non-green structure, thus
depending entirely on the gametophyte for
food.
 Inside sporogonium are present many spore
mother cells which remain surrounded by a
capsule wall and two-layered calyptra.

20.  Spore mother cells divide reductionally, and each
of them thus forms four haploid spores, arranged
tetrahedrally.
 6. Prior to the formation of spores, the wall of the
sporogonium as well as the inner layer of calyptra
dissolve, and thus only a single-layered calyptra is
present outside the spores.
 7. Elaters are absent .
 8. Neck of the long archegonium may remain
outside for some time but it ultimately withers.

21. Spore
 It is the first cell of the gametophytic generation.
 Shape of the spore is rounded or pyramidal.
 Each spore is surrounded by a thick, black or sculp-
tured wall.
 Wall of the spore consists of three layers: outermost
exine or exosporium, which is thick and sculptured;
middle thin mesosporium and: innermost, thin intine or
endosporium
 Spores are unicellular and uninucleate structures.
 In the cytoplasm are present many oil globules.
 Spores germinate into gametophyte.

22. Germination of spore

23. Life cycle