Transcript phylum_bryophyta

Kingdom Plantae
• They include familiar organisms such as trees, herbs, bushes, grasses,
vines, ferns, mosses, and green algae. The scientific study of plants, known
as botany, has identified about 350,000 extant species of plants, defined as
seed plants, bryophytes, ferns and fern allies.
•In the process known as "photosynthesis ", plants use the energy of the
Sun to make food and oxygen. This complex chemical reaction provides
nearly all the oxygen in Earth's atmosphere and all the food required by
living things. Although some protists and bacteria are capable of performing
photosynthesis, plants do most of the photosynthesis on Earth.
•The ancestors of modern plants evolved in the seas nearly 700 million
years ago. These primitive plants did not have many the structures we tend
to associate with plants in general, such as roots, stems, and leaves. The
evolution of these structures only occurred after plants appeared on land
some 265 million years later. Many scientists believe that the evolution of
these specialized structures and the wide variety of forms they can assume
largely accounts for the success and diversity of land plants we see now.
Phylum Bryophyta

Bryophytes include Liverworts, Hornworts and Mosses. Although most prefer
a moist environment, some bryophytes will colonize bare ground. Together
with lichens, they are the first plants to appear in a lifeless area.

Though enormously successful in their large number of species distributed
throughout the world, Bryophytes are all low-growing plants because they
lack the internal food and water-conducting tissues plants need in order to
grow to a large size.

There are about 14,000 different species of Mosses, grouped into three
main subclasses. Two of these are fairly small, Peat Mosses (Sphagnobrya)
and Andreaeobrya. The third is the much larger subclass of the Eubrya
which contains most of the world's Mosses. Mosses have stems and leaves
but no true roots and no internal plumbing systems.
 (Gr. bryon: moss; phyton: plant)
 A phylum of simple plants possessing no vascular
tissue and rudimentary rootlike organs (rhizoids). They
grow in a variety of damp habitats, from fresh water to
rock surfaces. Some use other plants for support.
 Mosses show a marked alternation of generations between
gamete-bearing forms (gametophytes) and spore-bearing forms
(sporophytes): they possess erect or prostrate leafy stems (the
gametophyte generation, which is haploid); these give rise to
leafless stalks bearing capsules (the sporophyte generation, which
is diploid), the latter being dependent on the former for water and
nutrients. Spores formed in the capsules are released and grow to
produce new plants.
6 classes of Bryophyta:
 Takakiopsida - The genus Takakia was established by Hattori and
Inoue in 1958 when the gametophyte of T. lepidozioides was found in Japan. In 1963，
a species described by Mitten in the hepaticae genus Lepidozia，L. ceratophylla，was
transferred to this genus by Grolle.
 Sphagnopsida - class of the plant division Bryophyta containing
plants commonly called peatmosses. The spongelike plants grow as perennials in soft
cushions or lawns in wet habitats (rarely they grow submerged).
 Andreaeopsida - A class of the plant division Bryophyta
distinguished by longitudinal splitting of the mature capsule into four valves;
commonly known as granite mosses.
 Andreaeobryopsida - is a genus of moss with a single
species Andreaeobryum macrosporum, endemic to Alaska and
western Canada.
 Polytrichopsida - is a common family of mosses.
Members of this family tend to be larger than other mosses with a
thickened central stem and a rhizome. The leaves have a midrib that
bears lamellae on the upper surface.

Bryopsida - constitute the largest class of mosses,
containing 95% of all moss species. It consists of approximately
11,500 species, common throughout the whole world.
Takakiopsida
Sphagnopsida
Andreaeopsida
Andreaeobryopsida
Polytrichopsida
Bryopsida
Moss growth
 Mosses form the largest
class of the bryophytes.
A magnifying lens can
reveal the beauty of
some of these tiny
plants that have made
the transition from
water to land. A Moss
plant that starts life as a
spore grows first into a
simple filament or
thallus. Then upright
leafy branches develop
with little rhizoids to
anchor the plant and
the Moss spreads over
the ground, trees or
rocks on which it is
growing.
Moss sex
 Like other Bryophytes,
Mosses reproduce sexually,
and fertilised eggs develop
into sporophytes which can
be seen sprouting from the
mother plant. Their little
stalks are topped by
capsules in which the spores
develop. Fertilisation takes
place only when there is
enough water around for the
sperm cells to swim to the
eggs. Look for the spore
capsules of Mosses in the
rainy season.
Class Psilopsida

whisk ferns; comprising the family Psilotaceae or
Psilotatae: vascular plants with no roots, partial if any
leaf differentiation, and rudimentary spore sacs.
 A subdivision or class of *vascular plants containing
two living genera, Psilotum and Tmesipteris, that
together constitute the order Psilotales.
 Psilotales - lower vascular plants having
dichotomously branched sporophyte divided into aerial
shoot and rhizome and lacking true roots.
Whisk Ferns
Whisk ferns (Psilophytes)
are an echo of the past and
they represent a great step
in the evolution of higher
plants. 420 million year old
fossils show that
Psilophytes flourished at
that time though very few
remain today. One species
of the genus Tmesipteris is
found in the islands of the
Pacific and two species
of Psilotum grow in
tropical and sub-tropical
countries throughout the
world.
Psilotum
Ancient Psilophytes had
branched green stems with no
true roots or proper leaves, but
they developed an internal
system of tubes to carry water
and foodstuffs. This made it
possible for plants to grow much
bigger than the little groundhugging bryophytes. This picture
is a section through the stem of a
modern whisk fern showing the
internal tubes.
Whisk Fern Spores
Whisk Ferns produce spores
which grow into small
underground masses of
tissue that develop sex
organs. The picture shows a
section through the spore
sacs of a present-day whisk
fern. The main plant can be
compared to
the sporophyte stage of a
moss. True ferns which show
a similar alternation of sexual
and spore-forming
generations almost certainly
evolved from primitive Whisk
Ferns.