3. Introduction to spagnum
Sphagnum is a genus of approximately 380
species of mosses, commonly known as
sphagnum moss, also bog moss and quacker
moss.
Accumulations of Sphagnum can store water,
since both living and dead plants can hold
large quantities of water inside their cells;
plants may hold 16 to 26 times as much water
as their dry weight, depending on the species.
The empty cells help retain water in drier
conditions.
5. Structure of gametophyte of
sphagnum
◦ The gametophyte (the dominant generation) is differentiated
◦ into a stem carrying leaves.
◦
◦ In young leaves all the cells are alike, in most leaves , there
◦ are two kinds of cells:
◦
◦ 1)long narrow cells which remain alive and contain chloroplasts
and they are green photosynthetic cells.
6. .
(photosynthetic cells have regular reticulate arrangement with respect to one another)
2)large cells with spiral thickening in their wall which lost their potoplast and become
hyaline.
(Hyaline cells play an important role in the absorption and retention of water)
The stem is internally differentiated into a central medulla followed by a cylinder of
hadrome and a cortex.
The cortex at first is one cell in thickness but later it becomes
4-5 cells in thickness.
The cells of the cylinder (hadrome) are thickwalled and form
a supporting tissue.
9. Reproduction
In
Sphagnum
●Sphagnum is homothallic(monocious) or
heterothallic(dioecious) according to species.
●Antheridia gives sperm
&Archegonia gives egg cell.
●Fertilization takes place and the resulting zygote gives a
sporophyte which consists of a foot with haustoria, short seta
and capsule.
●The amphithecium gives The jacket and the archespoium of
the capsule.
.
10.
11. ●The endothecium gives the columella and in this
respect is 3
-
4
cells in thickness.
●When the sporophyte matures the tissues of the
gametophyte just beneath the foot develop into a
leafless stalk known as the pseudopodium.
