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PLANT KINGDOM
ALGAE
Algae are chlorophyll bearing, simple autotrophic
aquatic organisms.
Occurrence
Moist stones, soils & wood or in association with
fungi & animals.
Form & size
 Microscopic unicellular forms -Chlamydomonas
 Colonial forms -Volvox
 Filamentous forms-Ulothrix,spirogyra
 Massive forms-Kelps
Reproduction
1.Vegetative reproduction – by fragmentation.
2.Asexual reproduction – by production of spores
called zoospores.
3.Sexual reproduction – by fusion of gametes.
a.Isogamous – gametes are similar in
size.eg:Chlamydomonas,Spirogyra
b.Anisogamous – gametes are dissimilar in size.
eg:Some species of chlamydomonas.
c.oogamous-One large,static gamete(female) &
other small motile gamete(male).
Significance
1.Increases the level of oxygen in the environment,
2.Many species are used as
food.eg:sargassum,chlorella,spiruillina.
3.Agar obtained from Gelidium & Gracilaria in used
in the preparation of icecreams & jellies.
4.Algin(brown algae) & carrageen(red algae) are
used commercially as hydrocolloids.
Class
Chlorophy
ceae
(Green
algae)
Major
pigments
Stored
food
Cell wall
Flagellar
Habitat
Position,
Position
of insertion
Chlorophyll
a&b
Starch
Cellulose
2-8,equal,
Apical
Fresh wa
ter ,brac
kish &
Salt
Mannitol,
Laminarin
Cellulose &
algin
2,unequal
lateral
cellulose
Absent
Phaeophy Chlorophyll
ceae(Brow a & c,
n Algae)
Fucoxanthin
Rhodophy
ceae (Red
algae)
Chlorophyll Floridean
a & d,
starch
Phycoerythri
n
“
“
Asexual reproduction
 By vegetative reproduction-fragmentation &
budding.
 By the formation of specialised structures called
Gemmae.Gemmae are green,
multicellular,asexual buds which develop in
small receptacles called gemma cups located on
the thalli.The gemmae detaches from the plant
body & germinate to form new individuals.
Sexual reproduction
 The main plant body of bryophyte is called
gametophyte which produces gametes.
 The male sex organ is called antheridium &
female sex organ is called archegonium.
 The biflagellate antherozoids produced from
antheridium is released into water & comes in
contact with archegonium.
 The antherozoid fuses with egg forming zygote.
 Zygote develops into a multicellular body called
sporophyte which produces spores.
 Spores germinate to produce plant body.
Significance
1.Species of sphagnum provide peat which is used
as hydrocolloid.
2.Provide food for herbaceous mammals, birds &
other animals.
3.They decompose rocks making the substrate
suitable for the growth of higher plants.
4.Prevent soil erosion.
5.Mosses along with lichens are the first to
colonize rocks & hence of great ecological
importance.
Bryophytes are divided into liverworts & mosses.
1.Liverworts (Marchantia)
The thallus is dorsiventral & closely appresed to the
substrate,they have leaf like appendages in two rows on
the stem like structures.
2.Mosses (Funaria,Polytrichum,Sphagnum)
Life cycle has mainly two stages –
stage 1- Protenema
Creeping green branched stage which directly develops
from the spore.
stage 2 – leafy stage
Develops from protonema as a bud.They consist of slender
axes bearing spirally arranged leaves,attached to the soil
through rhizoids.This stage bears sex organs.
Pteridophytes
These are first terrestrial plants to possess
vascular tissues- xylem & phloem.Usually
grown as ornamentals.Seeds were first
seen.
Occurrence
Generally found in cool,damp, shady places.
Form
The main plant body called sporophyte is
differentiated into true root ,stem & leaves.
Reproduction
 The sporophyte possess leaf-like structures called
sporophyll which bear sporangia.
 Sporangia produce spores by meiosis.
 Spores germinate to photosynyhetic thalloid
gametophytes called Prothallus.
 Prothallus bears antheridia & archegonia.
 Fusion of gametes results in a zygote.
 Zygote develops into a well differentiated plant body.
Based on the size of spores, there are two types of
reproduction
1.Homosporous reproduction- spores are of similar
kinds.eg:Most of the pteridophytes.
2.Heterosporous reproduction-spores are of dissimilar
size- megaspores & microspores.
Eg:Selaginella,Salvinia
Gymnosperms
Gymnosperms are plants in which the seeds are
naked. gymnos-naked & sperma-seeds.
Occurrence & form
They are well adapted to extremes of
temperature,humidity & wind & therefore is
widely distributed.Gymnosperms include
medium-sized trees or tall trees &
shrubs.Sequoia is one of the tallest tree
species.Roots in some are in association with
fungus in the form of mycorrhiza(pinus) while
collaroid roots are associated with nitrogen fixing
bacteria(cycas).Leaves are simple or compound.
Reproduction
 Gymnosperms are heterosporous producing
microspores & megaspores.
 The spores are arranged spirally along a axis to
form lax or compact strobili or cones.
 The strobili bearing microspore is called
microsporangiate or male strobili & strobili
bearing megaspore is called megasporangiate
or female strobili.
 The microspore develops into pollengrain &
megaspore into ovule.
 In gymnosperms the gametophytes donot have
a free existence as in bryophytes &
pteridophytes.
 Fusion of pollen & ovule results in zygote.
 Zygote develops into embryo & ovule into seeds.
Angiosperms
Angiosperms are the flowering plants where the
pollengrains & ovules are developed in
specialised structures called flowers.
Occurrence & form
They are exceptionally large group of plants
occuring in wide range of habitats.They range in
size from tiny almost microscopic to tall trees.
Angiosperms are divided into two classes.
Dicotyledons - characterised by having two
cotyledons.
Monocotyledons – have only one cotyledon.
Reproduction
 The male sex organ in a flower is stamen & female sex
organ is pistill.
 Ovary in the pistill encloses ovules.
 Ovules carry embryo sac which has a three celled
apparatus- 1egg cell & 2 synergids,three antipodal cells
& 2 polar nuclei.The polar nuclei fuses to form a
secondary nucleus.
 By pollination, pollen grains are carried to the stigma of
the pistill.
 Pollen tube develops,enters the embryo sac where two
male gametes are discharged.
 One of the male gamete fuses with egg forming
zygote,other fuses with secondary nucleus producing
PEN(primary endosperm nucleus) which is triploid.This
is called double fertilization.
 Zygote develops into embryo & PEN into endosperm
which provides nourishment to the developing embryo.