Plant Kingdom Class 11 Notes Biology Chapter 3

 Page 1


Points to Remember
Classification :
? Artificial System of Classification
 ? By Carolus Linnaeus, based on androecium structure and vegetative
characters.
? Natural System of Classification
 ? Based	on	natural	affinities	among	or ganisms
 ? Included external as well as internal features
 ? By Geroge Bentham and J.D. Hooker
? Phylogenetic System of Classfication
 ? Based on evolutionary relationships between the various organisms
 ? By Engler and Prantl
 ? Later on By Hutchinson
Numerical Taxonomy :
? Carried out using computers
? Based on all observable characteristics
? Data processed after assigning number and codes to all the characters.
 Advantages : Each character gets equal importance and a number of
characters can be considered.
Cytotaxonomy :
? Based on cytological informations.
? Gives importance to chromosome number, structure and behaviour.
Page 2


Points to Remember
Classification :
? Artificial System of Classification
 ? By Carolus Linnaeus, based on androecium structure and vegetative
characters.
? Natural System of Classification
 ? Based	on	natural	affinities	among	or ganisms
 ? Included external as well as internal features
 ? By Geroge Bentham and J.D. Hooker
? Phylogenetic System of Classfication
 ? Based on evolutionary relationships between the various organisms
 ? By Engler and Prantl
 ? Later on By Hutchinson
Numerical Taxonomy :
? Carried out using computers
? Based on all observable characteristics
? Data processed after assigning number and codes to all the characters.
 Advantages : Each character gets equal importance and a number of
characters can be considered.
Cytotaxonomy :
? Based on cytological informations.
? Gives importance to chromosome number, structure and behaviour.
Chemotaxonomy :
? Based on Chemical constitutents of the plants.
Algae :
? Chlorophyll bearing, simple, thalloid, autotrophic and largely aquatic
organisms.
Importance of Algae :
? Help 	 in	 carbon 	 dioxide 	 fixation	 by	 carrying	 out	 photosynthesis	 and	 have
immense economic importance.
? At	 least	 half	 of	 the 	 total 	 carbon 	 dioxide	 fixation	 on	 earth	 carried	 out	 by 	 them.
? Increases dissolved oxygen level in their environment.
? Many species like Laminaria, Sargassum, Porphyra etc. are used as food.
? Agar obtained from Gelidium and Gracilaria which is used in ice-creams
and jellies and to grow microbes.
? Algin obtained from brown algae and carrageen from red algae used
commercially as hydrocolloids.
? Chlorella and Spirullina are unicellular algae, rich in protein and used even
by space travellers.
? Algae are unicellular like Chlamydomonas, colonial like Volvox or or
filamentous 	 like	 spirogyra and Ulothrix. Occur in water, soil, wood moist
stones etc.
Algae are divided into 3 classes.
(i) Chlorophyceae
 ? Green algae, Main pigment is chlorophyll ‘a’ and ‘b’.
 ? Cell wall has inner layer of cellulose and outer layer of pectose.
 ? Has pyrenoids made up of starch and proteins.
 ? Pigment and pyrenoids are located in Chloroplast.
e.g., Chlamydomonas, Volvax, Spirogyra, Ulothrix, Chara.
(ii) Phaeophyceae
 ? Brown algae are brown coloured due to main pigments chlorophyll ‘a’,
Page 3


Points to Remember
Classification :
? Artificial System of Classification
 ? By Carolus Linnaeus, based on androecium structure and vegetative
characters.
? Natural System of Classification
 ? Based	on	natural	affinities	among	or ganisms
 ? Included external as well as internal features
 ? By Geroge Bentham and J.D. Hooker
? Phylogenetic System of Classfication
 ? Based on evolutionary relationships between the various organisms
 ? By Engler and Prantl
 ? Later on By Hutchinson
Numerical Taxonomy :
? Carried out using computers
? Based on all observable characteristics
? Data processed after assigning number and codes to all the characters.
 Advantages : Each character gets equal importance and a number of
characters can be considered.
Cytotaxonomy :
? Based on cytological informations.
? Gives importance to chromosome number, structure and behaviour.
Chemotaxonomy :
? Based on Chemical constitutents of the plants.
Algae :
? Chlorophyll bearing, simple, thalloid, autotrophic and largely aquatic
organisms.
Importance of Algae :
? Help 	 in	 carbon 	 dioxide 	 fixation	 by	 carrying	 out	 photosynthesis	 and	 have
immense economic importance.
? At	 least	 half	 of	 the 	 total 	 carbon 	 dioxide	 fixation	 on	 earth	 carried	 out	 by 	 them.
? Increases dissolved oxygen level in their environment.
? Many species like Laminaria, Sargassum, Porphyra etc. are used as food.
? Agar obtained from Gelidium and Gracilaria which is used in ice-creams
and jellies and to grow microbes.
? Algin obtained from brown algae and carrageen from red algae used
commercially as hydrocolloids.
? Chlorella and Spirullina are unicellular algae, rich in protein and used even
by space travellers.
? Algae are unicellular like Chlamydomonas, colonial like Volvox or or
filamentous 	 like	 spirogyra and Ulothrix. Occur in water, soil, wood moist
stones etc.
Algae are divided into 3 classes.
(i) Chlorophyceae
 ? Green algae, Main pigment is chlorophyll ‘a’ and ‘b’.
 ? Cell wall has inner layer of cellulose and outer layer of pectose.
 ? Has pyrenoids made up of starch and proteins.
 ? Pigment and pyrenoids are located in Chloroplast.
e.g., Chlamydomonas, Volvax, Spirogyra, Ulothrix, Chara.
(ii) Phaeophyceae
 ? Brown algae are brown coloured due to main pigments chlorophyll ‘a’,
‘c’ and fucoxanthin (xanthophyll)
 ? Cell wall has cellulose with gelantionous coating of algin.
 ? Has mannitol and laminarin (complex carbohydrate) as reserve food
material.
 ? Body divisible into holdfast, stipe and frond.
 ? e.g., Ectocarpus, Fucus, Laminaria, Dictyota, Sargassum
 (iii) Rhodophyceae
 ? Red algae are red coloured due to pigments chlorophyll ‘a’, ‘d’ and
r-phycoerythrin.
 ? Found on surface as well great depths in oceans.
 ? Cell wall has cellulose.
 ? Reserve	food	material	is 	floridean	starch.
e.g., Polysiphonia, Porphyra, Gelidium,Gracilaria.
Reproduction in Algae
Vegetative reproduction : by fragmentation
Asexual Reproduction : Flagellated zoospores in Chlorophyceae, 
Biflagellated 	 zoospores	 in	 Phaeophycease,	 By 	 non-motile	 spores	 in	 Rhodophyceae.
Sexual Reproduction : Isogamous, anisogamous or oogamous in 
chlorophyceae and Phaeophyceae. 
By non-motile gametes and oogamous in Rhodophyceae.
Bryophytes : 
? ‘Amphibians of plant kingdom’.
? Occur in damp, humid and shaded places.
? Lack true roots, stem or leaves.
? Main plant body is haploid and thallus like (prostrate or erect)
? Economic Importance : Food for herbaceous animals.
Sphagnum in from of peat is used as fuel and also used as packing material
for trans-shipment of living material, as it has water holding capacity.
Page 4


Points to Remember
Classification :
? Artificial System of Classification
 ? By Carolus Linnaeus, based on androecium structure and vegetative
characters.
? Natural System of Classification
 ? Based	on	natural	affinities	among	or ganisms
 ? Included external as well as internal features
 ? By Geroge Bentham and J.D. Hooker
? Phylogenetic System of Classfication
 ? Based on evolutionary relationships between the various organisms
 ? By Engler and Prantl
 ? Later on By Hutchinson
Numerical Taxonomy :
? Carried out using computers
? Based on all observable characteristics
? Data processed after assigning number and codes to all the characters.
 Advantages : Each character gets equal importance and a number of
characters can be considered.
Cytotaxonomy :
? Based on cytological informations.
? Gives importance to chromosome number, structure and behaviour.
Chemotaxonomy :
? Based on Chemical constitutents of the plants.
Algae :
? Chlorophyll bearing, simple, thalloid, autotrophic and largely aquatic
organisms.
Importance of Algae :
? Help 	 in	 carbon 	 dioxide 	 fixation	 by	 carrying	 out	 photosynthesis	 and	 have
immense economic importance.
? At	 least	 half	 of	 the 	 total 	 carbon 	 dioxide	 fixation	 on	 earth	 carried	 out	 by 	 them.
? Increases dissolved oxygen level in their environment.
? Many species like Laminaria, Sargassum, Porphyra etc. are used as food.
? Agar obtained from Gelidium and Gracilaria which is used in ice-creams
and jellies and to grow microbes.
? Algin obtained from brown algae and carrageen from red algae used
commercially as hydrocolloids.
? Chlorella and Spirullina are unicellular algae, rich in protein and used even
by space travellers.
? Algae are unicellular like Chlamydomonas, colonial like Volvox or or
filamentous 	 like	 spirogyra and Ulothrix. Occur in water, soil, wood moist
stones etc.
Algae are divided into 3 classes.
(i) Chlorophyceae
 ? Green algae, Main pigment is chlorophyll ‘a’ and ‘b’.
 ? Cell wall has inner layer of cellulose and outer layer of pectose.
 ? Has pyrenoids made up of starch and proteins.
 ? Pigment and pyrenoids are located in Chloroplast.
e.g., Chlamydomonas, Volvax, Spirogyra, Ulothrix, Chara.
(ii) Phaeophyceae
 ? Brown algae are brown coloured due to main pigments chlorophyll ‘a’,
‘c’ and fucoxanthin (xanthophyll)
 ? Cell wall has cellulose with gelantionous coating of algin.
 ? Has mannitol and laminarin (complex carbohydrate) as reserve food
material.
 ? Body divisible into holdfast, stipe and frond.
 ? e.g., Ectocarpus, Fucus, Laminaria, Dictyota, Sargassum
 (iii) Rhodophyceae
 ? Red algae are red coloured due to pigments chlorophyll ‘a’, ‘d’ and
r-phycoerythrin.
 ? Found on surface as well great depths in oceans.
 ? Cell wall has cellulose.
 ? Reserve	food	material	is 	floridean	starch.
e.g., Polysiphonia, Porphyra, Gelidium,Gracilaria.
Reproduction in Algae
Vegetative reproduction : by fragmentation
Asexual Reproduction : Flagellated zoospores in Chlorophyceae, 
Biflagellated 	 zoospores	 in	 Phaeophycease,	 By 	 non-motile	 spores	 in	 Rhodophyceae.
Sexual Reproduction : Isogamous, anisogamous or oogamous in 
chlorophyceae and Phaeophyceae. 
By non-motile gametes and oogamous in Rhodophyceae.
Bryophytes : 
? ‘Amphibians of plant kingdom’.
? Occur in damp, humid and shaded places.
? Lack true roots, stem or leaves.
? Main plant body is haploid and thallus like (prostrate or erect)
? Economic Importance : Food for herbaceous animals.
Sphagnum in from of peat is used as fuel and also used as packing material
for trans-shipment of living material, as it has water holding capacity.
Prevents 	soil 	erosion,	alongwith	lichens 	are 	first	colonizers 	on	barren	rock.
? Is divided into two classes Liverworts (thalloid body, dorsiventral, e.g.,
Marchantia) and Mosses (have two stages in gametophyte–creeping, green,
branched, 	 filamentous	 protonema stage and the leafy stage having spirally
arranged leaves e.g., Funaria, Polytrichum and Sphagnum).
Reproduction in Bryophytes
? Vegetative reproduction by fragmentation.
? Asexual reproduction by gemmae formed in gemma cups.
? Sexual reproduction : Main plant body is haploid, produces gametes and so
called Gametophyte. By fusion of antherozoids produced in antheridium
and egg cell produced in archegonium, results in formation of zygote which
develops into sporophytic structure differentiated into foot, seta and capsule.
Spores produced in a capsule germinate to from free-living gametophyt e
(Protonema). Sporophyte is not free living but attached to photosynthetic
gametophyte from which derives nutrition.
Pteridophytes :
? First terrestrial plants.
? Prefer cool, damp and shady places to grow.
? Grown as ornamentals.
? Used for medicinal purpose, as soil binder.
? Main plant body is sporophyte which is differentiated into true root, stem
and leaves.
? Leaves may be small as in Selaginella or large as in ferms.
? Sporangia having spores are subtended by leaf-like appendages called
sporophylls. (Sporphylls may be arranged to form strobili or cones.)
? In Sporangia, the spore mother cells give to spores after meiosis.
? Spores germinate to form haploid gametophytic structure called prothallus
which is free living, small, unicellular and photosynthetic.
? Prothallus bears antheridia and archegonia which bear antherozoids and
egg cell respectively which on fertilisation from zygote. Zygote produces
Page 5


Points to Remember
Classification :
? Artificial System of Classification
 ? By Carolus Linnaeus, based on androecium structure and vegetative
characters.
? Natural System of Classification
 ? Based	on	natural	affinities	among	or ganisms
 ? Included external as well as internal features
 ? By Geroge Bentham and J.D. Hooker
? Phylogenetic System of Classfication
 ? Based on evolutionary relationships between the various organisms
 ? By Engler and Prantl
 ? Later on By Hutchinson
Numerical Taxonomy :
? Carried out using computers
? Based on all observable characteristics
? Data processed after assigning number and codes to all the characters.
 Advantages : Each character gets equal importance and a number of
characters can be considered.
Cytotaxonomy :
? Based on cytological informations.
? Gives importance to chromosome number, structure and behaviour.
Chemotaxonomy :
? Based on Chemical constitutents of the plants.
Algae :
? Chlorophyll bearing, simple, thalloid, autotrophic and largely aquatic
organisms.
Importance of Algae :
? Help 	 in	 carbon 	 dioxide 	 fixation	 by	 carrying	 out	 photosynthesis	 and	 have
immense economic importance.
? At	 least	 half	 of	 the 	 total 	 carbon 	 dioxide	 fixation	 on	 earth	 carried	 out	 by 	 them.
? Increases dissolved oxygen level in their environment.
? Many species like Laminaria, Sargassum, Porphyra etc. are used as food.
? Agar obtained from Gelidium and Gracilaria which is used in ice-creams
and jellies and to grow microbes.
? Algin obtained from brown algae and carrageen from red algae used
commercially as hydrocolloids.
? Chlorella and Spirullina are unicellular algae, rich in protein and used even
by space travellers.
? Algae are unicellular like Chlamydomonas, colonial like Volvox or or
filamentous 	 like	 spirogyra and Ulothrix. Occur in water, soil, wood moist
stones etc.
Algae are divided into 3 classes.
(i) Chlorophyceae
 ? Green algae, Main pigment is chlorophyll ‘a’ and ‘b’.
 ? Cell wall has inner layer of cellulose and outer layer of pectose.
 ? Has pyrenoids made up of starch and proteins.
 ? Pigment and pyrenoids are located in Chloroplast.
e.g., Chlamydomonas, Volvax, Spirogyra, Ulothrix, Chara.
(ii) Phaeophyceae
 ? Brown algae are brown coloured due to main pigments chlorophyll ‘a’,
‘c’ and fucoxanthin (xanthophyll)
 ? Cell wall has cellulose with gelantionous coating of algin.
 ? Has mannitol and laminarin (complex carbohydrate) as reserve food
material.
 ? Body divisible into holdfast, stipe and frond.
 ? e.g., Ectocarpus, Fucus, Laminaria, Dictyota, Sargassum
 (iii) Rhodophyceae
 ? Red algae are red coloured due to pigments chlorophyll ‘a’, ‘d’ and
r-phycoerythrin.
 ? Found on surface as well great depths in oceans.
 ? Cell wall has cellulose.
 ? Reserve	food	material	is 	floridean	starch.
e.g., Polysiphonia, Porphyra, Gelidium,Gracilaria.
Reproduction in Algae
Vegetative reproduction : by fragmentation
Asexual Reproduction : Flagellated zoospores in Chlorophyceae, 
Biflagellated 	 zoospores	 in	 Phaeophycease,	 By 	 non-motile	 spores	 in	 Rhodophyceae.
Sexual Reproduction : Isogamous, anisogamous or oogamous in 
chlorophyceae and Phaeophyceae. 
By non-motile gametes and oogamous in Rhodophyceae.
Bryophytes : 
? ‘Amphibians of plant kingdom’.
? Occur in damp, humid and shaded places.
? Lack true roots, stem or leaves.
? Main plant body is haploid and thallus like (prostrate or erect)
? Economic Importance : Food for herbaceous animals.
Sphagnum in from of peat is used as fuel and also used as packing material
for trans-shipment of living material, as it has water holding capacity.
Prevents 	soil 	erosion,	alongwith	lichens 	are 	first	colonizers 	on	barren	rock.
? Is divided into two classes Liverworts (thalloid body, dorsiventral, e.g.,
Marchantia) and Mosses (have two stages in gametophyte–creeping, green,
branched, 	 filamentous	 protonema stage and the leafy stage having spirally
arranged leaves e.g., Funaria, Polytrichum and Sphagnum).
Reproduction in Bryophytes
? Vegetative reproduction by fragmentation.
? Asexual reproduction by gemmae formed in gemma cups.
? Sexual reproduction : Main plant body is haploid, produces gametes and so
called Gametophyte. By fusion of antherozoids produced in antheridium
and egg cell produced in archegonium, results in formation of zygote which
develops into sporophytic structure differentiated into foot, seta and capsule.
Spores produced in a capsule germinate to from free-living gametophyt e
(Protonema). Sporophyte is not free living but attached to photosynthetic
gametophyte from which derives nutrition.
Pteridophytes :
? First terrestrial plants.
? Prefer cool, damp and shady places to grow.
? Grown as ornamentals.
? Used for medicinal purpose, as soil binder.
? Main plant body is sporophyte which is differentiated into true root, stem
and leaves.
? Leaves may be small as in Selaginella or large as in ferms.
? Sporangia having spores are subtended by leaf-like appendages called
sporophylls. (Sporphylls may be arranged to form strobili or cones.)
? In Sporangia, the spore mother cells give to spores after meiosis.
? Spores germinate to form haploid gametophytic structure called prothallus
which is free living, small, unicellular and photosynthetic.
? Prothallus bears antheridia and archegonia which bear antherozoids and
egg cell respectively which on fertilisation from zygote. Zygote produces
33
multicellular, well differentiated sporophyte.
? The four classes are : Psilopsida (Psilotum), Lycopsida (Selaginella),
Sphenopsida (Equisetum) and Pteropsida (Pteris).
Heterospory : Two kinds of spores i.e., large (macro) and small (micro)
spores are produced. e.g.,Selaginella and Salvinia.
Seed Habit : The development of zygote into young embryos takes place 
within the female gametophyte which is retained on parent sporophyte. This event 
is precursor to seed habit and this is an important step in evolution and is found 
Selaginella and Salvinia among the pteridophytes.
Gymnosperms :
? Have naked seeds as the ovules are not enclosed by any ovary wall and
remain exposed.
? Includes shrubs and trees (medium and tall sized).
? Have generally tap roots, stem may be unbranched (Cycas) or branched
(Pinus, Cedrus), leaves–needle like (Pinus) and pinnate (Cycas).
? Roots of Pinus have fungal association in the form of mycorrhiza.
? Cycas have small specialized roots called coralloid root which are associated
with N
2
	fixing 	cyanobacteria.
? Heterosporous–Produce haploid microspores and megaspores.
? Male cone has microsporophylls which bear  microsporangia having
microspores which develop into reduced gametophyte called pollengrain.
? Female cone has megasporophylls which bear megasporongia having
megaspores which are enclosed within the megasporangium (Nucellus).
One megaspore develops into female gametophyte bearing two or more
archegonia.
? Pollen grains carried in air currents reach ovules, form pollen tube which
reach archegonia and release male gametes which fertilise egg cell and form
zygote which produce embryos. Ovules develop into seeds which are not
covered.