Reboulia

1. REBOULIA

2. SYSTEMATICPOSITION
KINGDOM : PLANTAE
DIVISION : MARCHANTIOPHYTA
CLASS: MARCHANTIOPSIDA
ORDER: MARCHANTIALES
FAMILY: AYTONIACEAE
GENUS: REBOULIA
SPECIES: R.hemisphaerica

4. OCCURREANCE AND DISTRIBUTION
□ Plants are found in dense patches of overlapping thalli which are green
with purple margins .
□ This is a perennial liverworts consisting of a low mat of dichotomously
branched thalli.
□ Reboulia has one species, R. Hemisphaerica earlier very widely
distributed in himalayas, south india and central india, but is now
becoming depleted in these areas.
□ It is widely distributed throughout the world ,occurring on all continents except
antartica.
□ The native purple-fringed liverwort(R.hemisphearica)is widely
scattered throughout Illinois,where it is uncommon overall.
□ In Illinois ,habitats include the rock walls of cave entrance, sandstone walls of
rocky hollows,ledges and crevices along north facing sandstone and
limestone cliffs,moist shaded areas of sandstone outcrops in
woodlands,shaded muddy banks of creeks, rocky wooded hillsides,etc….
□ Reboulia comprises of only a single polymorphic species, Reboulia
hemisphaerica,

5. EXTERNALMORPHOLOGY
□ Plant body is gametophyte,It is pale green, dichotomously branched thallus
with slightly undulate margins and a distinct midrib.
□ An individual thallus has a relatively flat ribbon- like appearance, becoming
slightly wider towards it’s growing tip. ;the latter is often deeply notched.
□ Thallus differentiate into dorsal and ventral region.
□ The upper surface of the thallus is light green, yellowish green and relatively
smooth ,indistinct white air pores are visible near upper surface.
□ The lower surface of the thallus is primarily purple.
□ Midrib is thick
□ Rhizoids and scales are arise from the ventral surface.
□ The thallus bears smooth and pegged rhizoids and 2-ranked ventral scales
without appendages .
□ Scales are one cell thick ,purplish and are arranged in two rows one on each
side of midribs.
□ The body of thallus is differentiated into a lower colorless region of compact
elongated cells and an upper region of loose chlorophyllose tissue containing
large air chamber.

6. □ Air chambers are abundantly formed and
developed by centripetal splittings and are
arranged in several rows.
□ Pores are somewhat elevated with 3 to 5 (rarely
upto 8)concentric rings of 6 to 8 cells each
□ No chlorophyllose filaments are formed.
□ The formation of a definite oil cells from an ordinary
vegetative cell is a common features of the genus.
□ No gemmae are produced.

8. T.SOF THALLUS
❑ Dorsal epidermal layer
containing cells which are 4-6
angled and pores(a little
elevated).
❑ Dorsal air chamber present
❑ Parenchymatous cell zone
❑ Ventral surface layer with purple
scales in one on each side of
the midrib and rhizoids

10. REPRODUCTION
⚫ Reproduction by means of vegetative and sexual
methods.
⚫ Vegetative reproduction by progressive death and
decay of the thallus
⚫ Specialized asexual reproduction is absent.
⚫ Sexual reproduction is oogamous type.
⚫ Gametes are produced in the sex
organs(antheridia and archegonia)
⚫ It may be dioecious or monoecious(autocious).
⚫ Antheridia(male sex organ) and
archegonia(female sex organ)

12. ARCHEGONIUM
⚫ The archegonia are borne on receptacles which arise as dome like
areas at the growing point of thallus .
⚫ Archegonial receptacles become lifted up on a stalk only after
sporophyte are approaching maturity.
⚫ Their stalk remain surrounded at the base and the apex by
narrow scales with a singles rhizoid furrow.
⚫ Receptacles are conical or hemispherical divided to the middle into 4
to 9 obtuse lobes.
⚫ The species(R.hemisphaerica) is presumably named after the
hemispherical shape of its female reproductive
organ(archegonium).
⚫ Air chambers with compound pores are found on them.
⚫ Involucre arise on the underside of the lobes from the margins.
These are bivalve.
⚫ Each involucre encloses a single sporogonium .Perianth is not
found.

13. ⚫ Archegonium has a swollen portion ,the venter and
elongated part,the neck .
⚫ Mature archegonium contains 18-20 neck canal
cells,but only 4 are present at the time of division of the
ventral cell.
⚫ The neck in all cases shows 6 cells in cross section , as
among other marchantiales, in reboulia the neck canal
cell is 4.

15. ANTHERIDIUM
⚫ Antheridia occur in sessile lunate receptacles which are
sometimes irregular in outline and broken up into several
pieces.
▪ Receptacles is cushion-shaped and slightly raised
above the general level of the thallus.
▪ The male receptacles are usually located only 1-10 mm
behind each female receptacle on the thallus.
▪ The number of antheridia in a receptacles varies from 16 to
100.
▪ Usually 2 or rarely 3 groups of antheridia are
produced successively on the thallus before the
appearance of the archegonial receptacle.

16. ⚫ Water is essential for fertilization.
⚫ Anthrozoids from antheridia are
liberated to the surrounding water.
⚫ During fertilization the ventre canal
cells and neck canal cells of
archegonia disintegrate.
⚫ The sperm or the anthrozoids
enters through the neck canal
cell and reaches the egg cell.
⚫ Undergoes fertilization, results in
diploid zygote.
⚫ The first cell of sporophytic
generation

17. SPOROGONIUM
⚫ Sporogonium consists of relatively large foot ,short
stalk(seta) and a globulose capsule.
⚫ The wall of the capsule is unistratose.Capsule
dehisces irregularly at the apex.
⚫ A single capsule of R.hemisphaerica produces
around 3,000 spores ,which are viable for atleast five
month.
⚫ Spores are brown,spherical,reticulate-lamellate with
broad wing.Unicellular
⚫ Elaters have two to three spiral thickenings and are
coiled,long and rarely branched.

20. ⚫ After fertilization male receptacle become somewhat shrivelled,while
female receptacle become elevated on a stalk (seta) about 1-3 cm
high.
⚫ Depending on the environmental condition and maturity ,the stalk can be
white,light green,yellow etc..
⚫ The dome shaped head of the female receptacle
(carpocepalum)become more lobed as it matures.These lobes
partially separated from each other by downward-sloping
indentations.
⚫ 4-7 ovoid spore cases are present the undersise of female
receptacles ,which is having white memberanous covering.
⚫ Mature spore cases become dark purple or black in colour,where as the
immature ones are light green or yellowish green.

22. LIFECYCLE

23. THANKYOU