The first edition of this book ‘‘PLANT LIFE DIVERSITY’’ comprised of eleven Chapters which include the following: 1. The characteristics of soil environment, 2. The plant kingdom, 3. Thallophyta (Fungi, Algae, Bacteria and Lichens), 4. Phycophyta (Algae), 5. Mycophyta (Fungi), 6. Lichens, 7. Bryophyta, 8. Pteridophyta (Ferns), 9. Angiosperms and Gynmnosperms, 10. Forms and functional adaptation of plant to ecosystem and 11. Growth in plants. This book is meant for students of Pre-Degree, B.Sc., B.Sc. (Hons) and M.Sc. of Biological group such as Plant Sciences, Zoology, Plant Breeding and Bio-sciences.
ABHISHEK ANTIBIOTICS PPT MICROBIOLOGY // USES OF ANTIOBIOTICS TYPES OF ANTIB...
BOOK: PLANT LIFE DIVERSITY
1.
2.
3.
4.
5.
6. Plant Life Diversity
O. B. Bello,
Associate Professor, Plant Genetics and Biotechnology,
Dean, College of Natural and Applied Sciences,
Fountain University, Osogbo, Nigeria.
7. About the Author
Bello, Omolaran Bashir, Ph.D., M.Sc., B.Sc.
E mail: obbello@fountainuniversity.edu.ng;
obbello@yahoo.com; obbello2002@yahoo.com, ;
obbello2002@gmail.com
Tel: (+234) 0803 561 8920.
He is an Associate Professor, Plant Genetics and
Biotechnology, and the Dean of the College of Natural and
Applied Sciences, Fountain University, Osogbo,
Nigeria. He obtained B.Sc. (Agriculture) from the University
of Ibadan, Ibadan, Nigeria, M.Sc. and Ph.D. Agronomy from the University of Ilorin, Ilorin.
(SIWES) Unit, and the Department of Biological Sciences with tremendous achievements.
He is the Editor in Chief, Fountain University Journal of Natural and Applied Sciences
(FUJNAS). His research focus is on maize breeding on enhanced protein quality, nitrogen use
efficiency, drought and Striga tolerance. He teaches courses in Genetics, Plant Pathology,
Ethnobotany, Soil Microbiology and Microbiology Ecology.
8. Course Contents
Topic: Plant Life Diversity
About the author
Course contents
1
2
3
CHAPTER 1 THE CHARACTERISTICS OF SOIL ENVIRONMENT 8
1.0 Differences between plants and animals
1.1 Characteristics of living things
1.1.1 Movement
1.1.2 Respiration
1.1.3 Nutrition
1.1.4 Irritability
1.1.5 Growth
1.1.5.1 Types of growth in plants
1.1.5.1.1 Chemotropism
1.1.5.1.2 Geotropism
1.1.5.1.3 Heliotropism
1.1.5.1.4 Sonotropism
1.1.5.1.5 Hydrotropism
1.1.5.1.6 Thermotropism
1.1.5.1.7 Electrotropism
1.1.5.1.8 Phototropism
1.1.5.1.9 Thigmotropism
1.1.5.1.10 Exotropism
1.1.5.1.11 Ecotropism
1.1.5.1.12 Amphotropism
1.1.5.1.13 Neurotropism
1.1.5.1.14 Photoperiodism
1.1.6 Excretion
1.1.7 Reproduction
1.1.8 Death
8
8
8
9
9
11
11
11
11
11
12
12
12
12
12
12
12
12
12
12
12
12
12
13
14
9. CHAPTER 2 THE PLANT KINGDOM 15
2.0 The Plant Kingdom
2.0.1 Characteristics of Plant Kingdom
2.1 Crypyogamae (Seedless plants)
2.2 Phanerogamae (flower bearing plants)
15
15
15
15
CHAPTER 3 THALLOPHYTA (FUNGI, ALGAE, BACTERIA AND LICHENS) 17
3.0 Thallophyta (Fungi, Algae, Bacteria and Lichens)
3.2 Characteristics of Thallophyta
17
17
CHAPTER 4 PHYCOPHYTA (ALGAE) 18
4.0 Phycophyta (Algae)
4.1 Characteristics of Algae
4.2 Classification of Algae
4.2.1 Green Algae
4.2.2 Brown Algae
4.2.3 Diatoms (Bacillariophyta)
4.2.4 Red Algae
4.2.5 Dinoflagellates
4.2.6 Euglenoids
4.2.7 Yellow-green Algae
18
18
19
19
20
20
21
22
22
24
CHAPTER 5 MYCOPHYTA (FUNGI) 25
5.0 Mycophyta (Fungi)
5.1 Fungi can be recognized by the following
5.2 Characteristics of Fungi
5.2.1 Fungi Heterotrophy characteristics
5.2.2 Fungi body form characteristics
5.3 Five classes of Fungi
5.3.1 Myxomycetes
5.3.2 Phycomycetes
5.3.2.1 Phytophthora
5.3.3 Ascomycetes
5.3.4 Uses of Yeast
5.4 Basidiomycetes
25
25
25
25
25
26
26
27
27
27
28
29
10. 5.5 Deuteromycetes (Fungi imperfectly)
5.6 Fungi plant diseases
5.7 Beneficial effects of Fungi
5.8 Harmful effects of Fungi
29
29
29
30
CHAPTER 6 LICHENS 31
6.0 Lichens
6.1 Characteristics of Lichens
6.2 Biology of Lichens
6.3 Mutual benefits of Algae and Fungi in Lichens
6.4 Reproduction in Lichens
6.5 Survival in Lichens
6.6 Uses and importance of Lichens
6.7 Classification of Lichens
6.7.1 Crustose Lichens
6.7.2 Foliose Lichens
6.7.3 Fructicose Lichens
31
31
33
35
36
37
37
37
38
38
38
CHAPTER 7 BRYOPHYTA 40
7.0 Bryophyta
7.1 Characteristics of Bryophyta
7.2 The three classes of Bryophytes
7.3 Differences between liverworts and mosses
7.4 Importance of Bryophytes
40
40
41
42
43
CHAPTER 8 PTERIDOPHYTA (FERNS) 44
8.0 Pteridophyta (Ferns)
8.1 Characteristics of Pteridophyta (Ferns)
8.2 Types of Ferns
8.2.1 Boston Ferns
8.2.2 Holly Ferns
8.2.3 Maidenhair Ferns
8.2.4 Stag horn Ferns
8.3 Importance of Ferns
44
44
44
44
44
45
45
45
11. CHAPTER 9 ANGIOSPERMS AND GYNMNOSPERMS 46
9.0 Angiosperms and Gynmnosperms
9.1 Gymnospermae
9.2 Characteristics of Gymnospermae
9.3 Angiospermae
9.4 Characteristics of Angiospermae
9.5 Characteristics of Monocotyledons
9.6 Characteristics of Dicotyledons
9.7 Differences between Gymnosperms and Angiosperms
46
46
46
46
46
47
48
48
CHAPTER 10 FORMS AND FUNCTIONAL ADAPTATION OF PLANT TO
ECOSYSTEM 50
10.0 Forms and functional adaptation of plant to ecosystems
10.1 Classes of aquatic ecosystem
10.1.1 Marine habitat
10.1.2 Estuarine habitat
10.1.3 Fresh water habitat
10.2 Adaptation of plants to aquatic habitat
10.3 Terrestrial Ecosystem
10.3.1 Grassland ecosystem
10.3.2 Tropical rainforest
10.3.3 Desert or arid habitat
10.4 Features of desert plant and their adaptations
10.4.1 Waxy cover
10.4.2 Little leaves
10.5 Marsh habitat
10.5.1 Types of marshes
10.5.2 Characteristics of marshes
50
50
50
50
50
52
52
52
52
52
53
53
53
53
53
53
Chapter 11 GROWTH IN PLANTS 54
11. Growth in plants
11.1 Growth in plants
11.2 Stages of growth in plants
11.2.1 Assimilation
54
54
54
54
12. 11.2.2 Expansion
11.2.3 Cell division
11.3 Cell enlargement in plants
11.4 Cell differentiation in plants
11.5 Apical growth in plants
11.6 Intercalary growth in plants
11.7 Differences between growth and development in plants
11.8 Differences between isometric and allometric growth in plants
11.9 Aspects of plant growth in plants
11.10 The root tip in plants
11.10.1 Meristem in roots
11.10.2 root cap in roots
11.11 The region of elongation in roots
11.12 The region of differentiation in roots
11.12.1 Epidermis
11.12.2 Cortex
11.12.3 Pericycle
11.12.4 Xylem
11.12.5 Phloem
11.12.6 Cambium
11.13 Water uptake in plants
11.14 Mineral uptake in plants
11.15 Plants absorb their nutrients in inorganic form
11.16 Gas exchange in roots
11.17 Rate of growth in plants
11.18 Factors affecting growth in plants
11.19 Epigeal and hypogeal germination in plants
References
54
54
54
54
54
54
54
54
54
55
55
55
55
55
55
56
56
56
56
56
56
56
57
57
59
59
59
60
13. Chapter 1
1.0 DIFFERENCES BETWEEN PLANTS AND ANIMALS
Living things are things that have life in them. Living things include plants and animals.
Examples for animals are tilapia, toad, lizard, sparrow and man. While for plants are hibiscus,
mango tree, sundew and green plants [1, 2].
Figure 1.0 Different plants and animals
1.1 Characteristics of living things
Living things are distinguished from non-living things by a number of characteristics which
is represented with MR NIGER D i.e. Movement, Respiration, Nutrition, Irritability, Growth,
Excretion, Reproduction and Death [1, 2].
11.1 Movement: Movement is commonly regarded as a sign of life. Movement in plants,
however are restricted as most of them are fixed to the ground, while animals move freely.
Movement in plants and animals can be spontaneous or induced.
14. Table 1.1.1 Characteristics of living things based on movement
Animal Plant
1 Animal movement is motile Plant is static
2 Animals are active and have organ of
movement
Plants are not active and have no organ of
movement
3 Animals move by organized function
of brain, nerve and muscles
Plants move by the surrounding forces of
atmosphere like air, water, or other pressure.
4 Animals can move themselves from
one place to another.
Plants can only move parts of their bodies in
response to external stimuli
5 Animals cells have specialized protein
which helps muscles to contract
Plant cells do not have specialized protein for
movement.
1.1.2 Respiration: All living things respire continuously day by day. Plants breathe in
carbondioxide and breathe out oxygen while animals breathe in oxygen and breathe out
carbondioxide. Respiration in plant is by stomata and in animal is by lungs[1, 2].
Table 1.1.2 Characteristics of living things based on respiration
Animal Plant
1 Animals use their lungs to respirate Plants use their stomata and lenticels roots to
respirate
2 Animals breathe in oxygen and
breathe out carbondioxide
Plants take in carbondioxide and take out
oxygen
3 As animals are heterotrophs they
get glucose from outside to carry
out respiration
Plant take in carbondioxide from the
environment to produce glucose inside the body
and hence are known as autotrophs
1.1.3 Nutrition: Plants and animals have almost the same feeding mode. These are ultimately
digested and assimilated by the protoplasm for its own nutrition and growth. The feeding
mode of plants is Autotrophic while in animals is Heterotrophic.
15. Table 1.1.3 Characteristics of living things based on nutrition
Autotrophic (Plant) Heterotrophic (Animal)
1 Plant manufacture their food on
their own
Animals depend on plant for their food
2 They are also called holophytic
nutrition
They are also called holozoic nutrition
3 They derive their own food by a
process called photosynthesis
They depend on either plant or animal for their food
4 Examples are euglena spirogyra blue
green Algae.
Examples are man, dog, tapeworm and plasmodium
Figure 1.1.3a Sun dew trapping an insect
16. Figure 1.1.3b A pitcher plant. (Family Nepenthaceae) (Genus-Nephenthes)
1.1.4 Irritability: It is the ability of an animal to respond to external stimuli be it plant or
animal. Living things exhibit sensitivity in order to enable them to survive in their
environment. Stimuli include heat, light, pain, water, sound and chemical substances to which
living things respond [1, 2].
Table 1.1.3 Characteristics of living things based on irritability
Animals Plants
1 Dispense faster to stimuli. Respond to stimuli but not as fast as animal.
2 All animals respond to stimuli. Not all plant respond to stimulus.
3 Animal uses sensory impulses with aid
of cerebrum.
Plants do not have cerebrum for impulses.
4 Examples are snail, tortoise millipedes. Pitcher plant, Mimosa pudica (sensitive
plant) and Sundew.
1.1.5 Growth: Growth is defined as a permanent increase in size and mass in an organism.
the purpose is to enable organism to replace damaged or old tissues in their bodies. The food
eaten provides the basis for growth of organism [1, 2].
1.1.5.1 Types of growth in plants
1.1.5.1.1 Chemotropism: Movement or growth in response to chemicals.
1.1.5.1.2 Geotropism: Movement or growth in response to gravity.
17. 1.1.5.1.3 Heliotropism: Movement or growth in response to sunlight.
1.1.5.1.4 Sonotropism: Movement or growth in response to sound.
1.1.5.1.5 Hydrotropism: Movement or growth in response to water.
1.1.5.1.6 Thermotropism: Movement or growth in response to temperature.
1.1.5.1.7 Electrotropism: Movement or growth in response to electric field.
1.1.5.1.8 Phototropism: Movement or growth in response to light.
1.1.5.1.9 Thigmotropism: Movement or growth in response to touch or contact.
1.1.5.1.10 Exotropism:
1.1.5.1.11 Ecotropism: Limited host range (e.g infects only one species or cell type).
1.1.5.1.12 Amphotropism: Wide host range (e.g infects many species or cell types used by a
given strain of HIV).
1.1.5.1.13 Neurotropism:
1.1.5.1.14 Photoperiodism: This responds to seasons [1, 2].
Table 1.1.5 Characteristics of living things based on growth
Animals Plants
1 Growth is definite. Growth is indefinite.
2 Growth is intercalary. Growth is apical.
3 Animal cells are rounded, which
accounts for the variety of shapes and
sizes.
Plant cells are rectangular, helping to
form long stems and trunks.
4 Animals depend upon their parents to
varying degrees from protecting a
nest to nursing and weaning
for resources after germination.
1.1.6 Excretion: Excretion is defined as the removal of metabolic waste products from the
body. The purpose is to remove waste products of metabolism e.g. water, carbon dioxide, etc.
which are poisonous or toxic to the body [1, 2].
18. Table 1.1.6a Characteristics of living things based on excretion
Animals Plants
1 Excretion in animals is carried out by
the lungs, liver, kidney and skin.
Excretion in plants is carried out by stomata
and lenticels.
2 Excretory products in animals are
(a) Carbon dioxide
(b) Bile pigment
(c) Uric acid
(d) Creatinine
(e) Urea
Excretory products in plants are
Oxygen
Tannis
Alkaloids
Anthocyanin
Latex
Table 1.1.6b The organism, excretory organs and waste products
Organism Excretory organs Waste products
1 Protozoa e.g amoeba Contractile vacuole, Body
surface
CO2,H2O, excess mineral salts
2 Flatworms e.g
Tapeworms
Flame cells CO2, H2O, urea nitrogenous
waste.
3 Roundworms e.g
Earthworms
Nephridia Nitrogenous waste, Urea, CO2
4 Insects e.g cockroach Malphighian tubules CO2, H2O, Uric acid
5 Vertebrates e.g
Mammal
Lungs, liver, kidney, skin Nitrogenous waste, CO2, H2O.
6 Flowering plants e.g
Tannis
Stomata and lenticels Latex, mucilage, alkaloids
1.1.7 Reproduction: Reproduction is defined as the ability of a living organism to give birth
to you
be passed on from one generation to the next.
a. Asexual reproduction: this involves only one organism to produce another offspring.
b. Sexual reproduction: this involves two organisms coming together for the purpose of
reproducing [1, 2].
19. Table 1.1.7 Characteristics based on sexual and asexual reproduction
Sexual Reproduction (Animals) Asexual Reproduction(Plants)
1. Two parents are required to mate except in
hermaphrodites.
One parent is needed to mate.
2.It involves the fusion of male and female
gametes
No gametes involved
3. Cell division is done by meiosis. Cell division is done by budding or fission.
4. Zygote is formed. Zygote is not formed.
show new variation.
1.1.8 Death: All living things must die because they have a definite and limited period of
existence. All living things must pass this five (5) stages of life namely:
Birth Growth Maturity Decline(old age) Death.
The animals typically do not live more than two hundred years, while plants can live for
hundreds of years [1, 2].
20. Chapter 2
2.0 THE PLANT KINGDOM
The Kingdom Plantae can be defined as multicellular, autotrophic eukaryotes, which conduct
photosynthesis. All member of this family comprises of true nucleus and advanced membrane
bound organelles. The Kingdom Plantae contains about 300,000 different species of plants. It
is divided into two sub kingdoms, which are; i. Cryptogamae and ii. Phanerogamae [1, 3].
2.0.1 Characteristics of Plant Kingdom
i. Most of the plants are eukaryotic and chlorophyll containing organisms.
ii. Cell walls of plant cells are comprised of cellulose.
iii. They have an ability to grow by cell division.
iv. In life cycle of plant cells, the interchanges occur from the embryos and are supported by
other tissues and self-produce.
v. Plants have organs and systems.
vi. They obtain their energy from sun through photosynthesis.
vii. Plants reproduce both by sexual and asexual.
viii. Plants develop a self-defence mechanism to protect them from being destroyed by
animals, fungi and other plants.
ix. Organisms within Kingdom Plantae are multicellular, eukaryotic and autotrophic.
x. They lack motility [1, 3].
2.1 Crypyogamae (Seedless plants)
This includes all seedless and flowerless plants. Lower cryptogamae lack true stem, leaves
and vascular system. Higher do have true stem and vascular system. These plants reproduce
by producing spores. Cryptogamae is further divided into three divisions, which are;
Thalophyta, Bryophyta, Pteridophyta [1, 3].
2.2 Phanerogamae (flower bearing plants)
Phanerogams are flower bearing, seed producing tracheoptytes . This sub kingdom has only
one division Spermatophyta, i) Gymnospermae (Monocot) and ii) Angiospermae (Dicot).
22. Chapter 3
3.1 THALLOPHYTA (FUNGI, ALGAE, BACTERIA AND LICHENS)
The Thallophytes (Thallophyta or Thallobionta) are a polyphyletic group of non-mobile
organisms traditionally described as "thalloid plants", "relatively simple plants" or "lower
plants". They include all those lowly plants which are devoid of stem, root and leaves. They were
a defunct division of Kingdom Plantae that included fungus, Lichens and Algae and bacteria. In
the Algae and Fungi the simpler forms consist of a single cell or of a small colony of cells. In the
higher forms, thallus or the body consists either of a filament of cells joined end to end, or of
cellular tissue or system of filaments, running longitudinally and/ or transversely, embedded in
the mucilage [1, 3].
3.2 Characteristics of Thallophyta
i. Thallophyta usually found in moist or wet places.
ii. They are autotrophic, i.e. manufacture their own food and reserve food is generally stored as
starch.
iii. They have a cellulose cell wall around their cells. Mechanical & conducting elements are
absent.
iv. The mode of nutrition is photosynthetic, parasitic or saprophytic. Chlorophyll present only in
the Algae, and could be masked by other pigments.
v. Sexual reproduction usually occurs, but the process varies, which shows very instructive
stages of evolutionary development towards increased complexity in the Algae, and towards
simplification and reduction in the Fungi.
vi. Sex organs are simple and single celled without embryo formation after fertilization. They
reproduce both sexually and asexually.
vii. Asexual reproduction usually reproduction takes place by spore formation.
viii. Fertilization is not followed by embryo formation. Sexual reproduction is presently
unknown in Euglenophyceae.
ix. The Bacteria in this phylum are either unicellular or filamentous, devoid of chlorophyll. The
reproduction is by a simple process of fission [1, 3].
23. Chapter 4
4.0 PHYCOPHYTA (ALGAE)
Phycophyta are also referred to as Algae are chlorophyll bearing thalloid, autotrophic and
largely autotrophic and largely aquatic (fresh water and marine water) plants. They also occur in
a variety of other habitats, moist stones, soils wood they are unicellular also occur in association
with fungi to form Lichens. They are also referred to as Algae are a very large and diverse group
of eukaryotic organisms, ranging from unicellular genera such as Chlorella and the Diatoms to
multicellular forms such as the Giant Kelp, a large Brown Alga that may grow up to 50 meters in
length. Most are autotrophic and lack many of the distinct cell and tissue types found in land
plants such as stomata, xylem and phloem. The largest and most complex marine Algae are
called seaweeds, while the most complex freshwater forms are the Charophyta, a division of
Algae that includes Spirogyra and the . Algae exhibit a wide range of reproductive
strategies, from simple asexual cell division to complex forms of sexual reproduction [1, 2, 3].
4.1 Characteristics of Algae
i. Most Algae are aquatic both fresh and marine water some are terrestrial inhabiting in the
moist places.
ii. They exhibit autotrophic mode of nutrition. Most Algae contain green pigment while
other contains red, brown, blue-green or purple pigment.
iii. The cell wall is made up of cellulose
iv. Some of the Algae like Chlamydomonas are unicellular while some are colonial (Volvox)
or filamentous (Spirogyra, Ulithrix).
v. The mode of reproduction is usually asexual but sexual reproduction also takes place in
some of the forms.
vi. Algae are the source of about 50% of the total of the organic matter on this earth.
vii. Most are phototrophic, although some groups contain members that are mixotrophic,
deriving energy both from photosynthesis and uptake of organic carbon either by
osmotrophy, myzotrophy, or phagotrophy.
viii. Algae exhibit a wide range of reproductive strategies, from simple asexual cell division
to complex forms of sexual reproduction [1, 2, 3].
24. 4.2 Classification of Algae
Algae are classified into seven groups namely;
i) Green Algae: Chlorophyta,
ii) Brown Algae: Phalophyta,
iii) Diatoms: Bacillariophyta,
iv) Red Algae: Rhodophyta,
v) Dinoflagellate: Pyrrophyta,
vi) Euglenoids: Euglenophyta and
vii) Yellow-green Algae: Chrysophyta [1, 2, 3]
4.2.1 Green Algae
They are the large group of Algae within which the Embryophytes (higher plants) emerge in the
Charophytes. Examples include; Sea lettuce, Green sea velvet, Caulerpa and Spirogyra [1, 2, 3].
Figure 4.2.1a Sea lettuce Figure 4.2.1b Green sea velvet
25. Figure 4.2.1c Spirogyra
4.2.2 Brown Algae
The Phaeophyceae or Brown Algae, is a large group of mostly marine multicellular Algae,
including many seaweeds of colder Northern Hemisphere waters. They play an important role in
marine environments, both as food and for the habitats they form. Examples of brown Algae
include Globe Algae, Leather kelp, Strap weed and necklace [1, 2, 3].
Figure 4.2.2a Globe Algae Figure 4.2.2b Leather kelp Algae
4.2.3 Diatoms (Bacillariophyta)
Diatoms are a major group of Algae, and are among the most common types of phytoplankton.
Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or
ribbons (e.g. Fragilaria), fans (e.g. Meridion), zigzags (e.g. Tabellaria), or stars (e.g.
Asterionella). Diatoms are producers within the food chain. A unique feature of diatom cells is
26. that they are enclosed within a cell wall made of silica (hydrated silicon dioxide) called a
frustule. They are divided into two groups; a) Centrales eg, Cyclotella, Isthmian, Rutilaria and
Corethron. b) Pennales eg. Fragilaria, Navicula, Eunotia, Epithemia and Pinnularia [1, 2, 3].
Figure 4.2.3a Fragilaria Figure 4.2.3b Epithemia
4.2.4 Red Algae
The red Algae, or Rhodophyta, are one of the oldest groups of eukaryotic Algae, and also one of
the largest, with about 5,000 6,000 species of mostly multicellular, marine Algae, including
many notable seaweeds. Examples of Red Algae includes: Palmaria, Delesseria and Condrous.
Figure 4.2.4a Palmari Figure 4.2.4b Delessria
27. 4.2.5 Dinoflagellates
The Dinoflagellates are a large group of flagellate protists that constitute the phylum
Dinoflagellata. Most are marine plankton, but they are common in fresh water habitats as well.
Their populations are distributed depending on temperature, salinity, or depth. Many
Dinoflagellates are known to be photosynthetic, but a large fraction of these are in fact
mixotrophic, combining photosynthesis with ingestion of prey (phagotrophy). In terms of
number of species, Dinoflagellates form one of the largest groups of marine eukaryotes, although
this group is substantially smaller than the diatoms. Some species are Endosymbionts of marine
animals and play an important part in the biology of coral reefs. Examples include: Pfisteria
piscicidia, Gonyaulax catanella, and Noctiluca scintillans[1, 2, 3].
Figure 4.2.5a Pfisteria piscicidia Figure 4.2.5b Gonyaulax catanella
4.2.6 Euglenoids
Euglenoids (or Euglena) are one of the best-known groups of flagellates, which are excavate
eukaryote of the phylum Euglenophyta and their cell structure is typical of that group. They are
commonly found in freshwater, especially when it is rich in organic materials, with a few marine,
and endosymbiotic members. Most euglenoids are unicellular. Many euglenoids have
chloroplasts and produce energy through photosynthesis, but others feed by phagocytosis, or
strictly by diffusion [1, 2, 3].
29. 4.2.7 Yellow-green Algae
A group of common single-celled and colonial Algae of the phylum Chrysophyta, having mostly
yellow and green pigment, occurring in soil and on moist rocks and vegetation and also as a
slime or scumon ponds and stagnant waters. Examples of Yellow-green Algae are Heterochloris,
Misclococcus and Chlorogloea [1, 2, 3].
Figure 4.2.7a Heterochloris Figure 4.2.7b Mislococcus
30. Chapter 5
5.0 MYCOPHYTA (FUNGI)
Fungi are living organisms that are distantly related to plants and more closely related to animals,
but rather different from either of those groups i.e. plant and animal. They are commonly made
up of an interwoven of very fine thread called hyphea and collective called mycelium. They are
non chlorophylls group of thallophytic plant (non framing embryo). They lead heterotrophic
mode of life either as saprophytes or parasites. The saprophytes grows in a varieties of situation
provided there is moisture, warmth and supply of organic food, while the parasite grow on the
lying plant and animals including human beings [1, 2, 3].
5.1 Fungi can be recognized by the following;
i. The cells of fungi contain nuclei with chromosomes.
ii. Fungi cannot photosynthesize (they are heterotrophic like animal).
iii. Fungi absorb their food i.e. they are osmotrophic.
iv. They mostly develop very diffuse bodies made up of a spreading network of very narrow
tabular, branching filaments called hyphae.
v. They usually reproduce by means of spores.
5.2 Characteristics of Fungi
5.2.1 Fungi Heterotrophy characteristics: There are three major categories of heterotrophy,
which include the saprophytes, symbionts and parasites. Saprophytes feed on dead tissues or
organic waste, symbionts (naturally beneficial relationship between a fungus and host), parasites
(feeding on living tissues of a host). Parasites that cause disease are called pathogens. Some
parasites are not obligate parasites (require a living host to survive).
5.2.2 Fungi body form characteristics
i. It is unicellular.
ii. Filamentous (tube like strands called hypha).
iii. Mycelium: - aggregate of hyphae.
iv. Sclerotium: - hardened mass of mycelium.
v. Fungus is often hidden from view. It grows through its food source.
vi. Indeterminate growth
vii. Spores; asexual (product of mitosis) or sexual (product of meiosis).
31. viii. Vegetative phase of fungus is generally sedentary.
ix. Cell wall present composed of cellulose.
x. Food storage; generally in the form of lipids and glycogen.
xi. Eukaryotes; true nucleus and other organelles[1, 2, 3].
5.3 Five classes of Fungi
a. Myxomycetes, eg . Didymium iridis, and Aecidium,
b. Phycomycetes, eg Phytophthora, Pythium and Mucor,
c. Ascomycetes, eg Yeast, Penicilium and Aspergillus,
d. Basidiomycetes, eg Uredo, Caeoma, and Perdermium and
e. Deuteromycetes, Fungi imperfecti eg Fusarium [1, 2, 3]
5.3.1 Myxomycetes: They animal like in their stage and plant-like in reproductive stages, in
humus rich soil, old planks of wood, rotten logs of decaying leaves e.t.c. They are saprophytic in
nature. The body is a naked slimy mass of protoplasm with many nuclei. The body is called
plasmodium; which forms pseudopodia .For creeping over and within the substratum. The
plasmodium feeds by engulfing solid particles of food and by absorbing food materials in
solution. E.g Didymium iridis and Aecidium.
Figure 5.3.1a Didymium iridis Figure 5.3.1b Aecidium
32. 5.3.2 Phycomycetes: Possessing hyphae usually without cross walls (non-septate, aseptate),
reproducing asexually by zoospores, aplanospores or conidia, and sexually with formation of
thick-walled resting spores. The mycelium is uniseptate (no cross wall) and coenocytes. Have
many sporangium sporangiophores and form endogenously e.g. are saprolegnia, water mode
grows in water as saprophytes on dead bodies of insect and fishes and on plant remains. They
may also be parasite on living fish and fish eggs, and may dwell on soil. Pythium is a parasitic
fungus commonly attaching seedlings at the base of the hyprocotocal especially under conditions
of overcrowding and over-watering. They caused the disease known as damping-off where
seedlings became weaken at their base and soon fall over. The mycelium grows between the
intracellular spaces into the lining tissue of the plants [1, 2, 3].
Figure 5.3.2 Phycomycetes
5.3.2.1 Phytophthora: It is a parasitic fungus that cause late blight disease in pepper, egg plant
and portative. The species are also found in coconut and other palms. It is symptomised by black
patches on the under surface of the leaves. The disease may spread to the entire leaf and down to
the underground tubers of potato. It spread faster under warm and humid weather. The mycelium
grows through intracellular spaces and ramifies the entire plant up to the roots and tubers.
5.3.3 Ascomycetes: The class has separate mycelium with primary mycelium either uni or multi
nucleoids. Conidial is a common feature. They possessed hyphae with cross walls (septate), with
asexual reproduction by conidia and sexual reproduction with formation of ascospores in an
almost spherical or cylindrical cell, the ascus. In most Ascomycetes the asci are grouped within
33. fruit-bodies (Cleistocarp, Apothecium and Perithecium) visible to the naked eye. They grow in
organic substance rich in sugar such as palm wine, date palm, and grapes, changing sugar to
alcohol. Examples are; i. Yeast ii. Penicilium, iii. Lichens and iv. Aspergillus.
Figure 5.3.3a Yeast
5.3.4 Uses of Yeast
i. Fermentation process such as manufacturing of beer.
ii. It is used in preparation of industrial alcohol from various cereals.
iii. It is use in bread making, giving sponginess and flavour to the loaf.
iv. It is rich in vitamins.
v. Used in medication.
vi. It has a nutrition value being rich in digestive compound especially protein and fats [1, 2, 3].
Figure 5.3.3b Penicilium Figure 5.3.3c Aspergillus
34. 5.4 Basidiomycetes; with septate hyphae and sexually produced spores, basidiospores, borne
externally on a club-shaped or cylindrical cell, the basidium. In some members the basidia are
grouped together in highly-organized fruit-bodies, e.g. mushroom, puff-ball, stink-horn, bracket
fungus.
5.5 Deuteromycetes (Fungi imperfectly): It is a group of fungi with septate hyphae that lack a
sexually reproducing stage, thought to be mostly asexual forms of Ascomycetes in which sexual
stage has been lost during evolution or has not yet been identified.
5.6 Fungi plant diseases: They caused several diseases in plant causing rotation for e.g
Helminthosporum causing spot disease in rice and maize. E.g Uredo, Caeoma, Perdermium.
Fungicides are biocidal chemical compounds or biological organism used to kill fungi. The study
of fungi is known as mycology [1, 2, 3]. The kingdom of fungi is an ensemble of diverse species.
Current evidence suggests are not derived from a single common ancestor, consequently the
fungi are polyphyletic (multiple genealogies or lineages).
Figure 5.6a Uredo Figure 5.6a Caeoma
5.7 Beneficial effects of Fungi
i. Decomposition; nutrient and carbon recycling.
ii. Biosynthetic factories; can be used to produce drugs, antibiotics, alcohol, acids, food.
iii. Model organism for biochemical and genetic studies.
iv. It feeds on dead organic matter which includes leaf, litter, soil, dung, wood and dead
animals.
35. v. Certain mushrooms such as ganoderma lucidum, agaricus subrufescens and cordyceps
sinesis enjoy usage as theraperutoes in traditional Chinese medicine.
vi. Some fungi are edible these include straw mushrooms and Portobello mushrooms are
commonly used in salads and soups.
vii. Fungi are used to produce industrial chemicals including citric, malic and lactic acids.
viii.. It increases soil nutrients [1, 3].
5.8 Harmful effects of Fungi
a. Destruction of food, lumber, paper and cloth.
b. They are poisonous in nature.
c. They destroy plant.
d. They also spoil fruits, vegetables and all kinds of food stuff.
e. They induce animal and human diseases e.g mycosis caused by infestation of Aspergillus,
Crysptococcus.
f. They cause disease in important crops e.g Late blight of potato.
36. Chapter 6
6.0 LICHENS
Lichens were first discovered in 1852 by Tulasne. Lichens are peculiar group of plants being a
composite of two different plant species in close symbiotic association [1, 3]. These lower plant
components are;
a. Fungal components: (Mycobront)
b. Algal component: (Phycobront)
The mycobronts involved are mostly ascomycetes, the Lichens is called Asolichens and in few
cases BasidioLichens. The hyphea of the fungi component encloses a unicellular or filamentous
algal component which is either a cyanophyceae (blue green) or chlorophyceae (green Algae).
The types of the Algae and the fungus associated in Lichens are always constant. Lichens have a
variety of brown, red or black. They occur as micrustations of several cm in diameter on tree
trunk wooden posts, tops of wood, rocks, walls and ground. Atimes they are seen hanging in tufts
shrubs, few to several cm long from branches of tree. They may be leaf like or finger like. The
two organized lead a symbiotic life of mutual benefits to each other. The Algae being green
prepare food and supply it to the fungi, while fungi with their hyphae, absorb them to the Algae.
Also fungi give protection, support and organ of attachment to the Algae [1, 2, 3].
6.1 Characteristics of Lichens
i. They grow on rocks tree trunks, old walls and even on ground. By nature they are very
hardy and can survive even in adverse conditions. They look grey green or may be
brightly coloured.
ii. Lichens are symbiotic association of specific group. Fungus and Algae. Fungus
constitutes bulk of the body of the Lichens. It absorbs and nutrients from the
surroundings and provides them to their Algae partner, which in turn manufactures food
and supplies to the fungus. Therefore it shows perfect symbiotic association.
iii. Lichens can reproduce both sexually and asexually.
37. Figure 6.1a Lichens growing on a back tree
Figure 6.1b Lichens growing on a back tree
38. Figure 6.1c Lichens growing on a rock
6.2 Biology of Lichens
Lichens are a symbiosis of at least two quite different organisms. The partnership always
involves a fungus, which lives with one or more partners which can do photosynthesis [1, 2, 3].
The photobiotic partner may be a green alga and/or a cyanobacterium. Lichens is a simple
composite plants consisting of fungus in a close symbiotic of an alga in a single thallus typically
growing on rocks, walls and trees. Lichens were first discovered in 1852 by Tulsane. Lichens are
peculiar groups of plants being a composition of two different plant species in close symbiotic
association. The Algae or bacteria live inside the fungus, and exchange nutrients with it. The
Lichens is different in shape and mode of life from any of the partners. It is a distinct form of
life. Examples of Lichens are: lettuce Lichens, Kananakis Lichens, Squamulous, Log Lichens,
Caribou, Blistered Jelly, Caloplaca-marina, etc.
40. Figure 6.2e Blistered Jelly Lichens
6.3 Mutual benefits of Algae and Fungi in Lichens
i. The photobiont provides photosynthetic products: carbohydrates as sugar alcohols (green
Algae) or glucose (cyanobacteria). The bacteria also convert atmospheric nitrogen (N2) to
ammonium ions (NH4
+
) which the fungus can use in amino acids for proteins.
ii. The alga certainly benefits from a supply of water (which the fungus is good at storing).
There is also general mechanical protection.
iii. Algae get protection from ultraviolet light, which in some environments is quite
significant. Algal cells are sometimes destroyed in the course of nutrient exchange,
though the algal cells divide and replace them. Above all, the partnership is a resounding
success, and gets to places where few other plants can survive.
iv. Fungus part of the Lichens provides the alga with water and minerals that the fungus
absorbs from whatever the Lichens is growing on.
v. As for the alga, it uses the minerals and water to make food for the fungus and itself from
the substrate or from dust settling on the thallus.
vi. Lichens take the external shape of the fungal partner and hence are named based on the
fungus [1, 2, 3].
41. Figure 6.3a Fungus component of Lichens Figure 6.3b Algae component of Lichens
6.4 Reproduction in Lichens
Many Lichens reproduce without sex (asexual reproduction). They make small groups of algal
cells surrounded by fungal filaments. These soridia can be blown by wind. Some Lichens just
break up into fragments when they dry. Wind carries the pieces, which grow when moisture
returns. Also, Lichens fungi can reproduce sexually by forming fruiting bodies containing
spores. These fruiting bodies are usually perennial, and may be long-lasing: some in the Swiss
Alps have lived for over 50 years. After dispersal by wind, such fungal spores must meet with an
algal partner to form Lichens [1, 2, 3].
Figure 6.4a Lichens reproduction Figure 6.4b Lichens reproduction
42. 6.5 Survival in Lichens
Lichens do survive extreme conditions. They are found in some of the most extreme places on
Earth the frozen north, hot deserts, and rocky coasts. They are common as epiphytes on leaves
and branches in rain forests and temperate woods. They can live on bare rock, walls and
gravestones, and on exposed soil surfaces. The European Space Agency red that Lichens can
survive unprotected in space. Two species of Lichens were sealed in a capsule and launched on a
Russian Soyuz rocket. Once in orbit the capsules were opened. Two species of Lichens were
exposed to the vacuum of space, to cosmic radiation and huge swings of temperature. After 15
days the Lichens were retrieved and were found to be in full health: no damage was found [1, 2,
3].
6.7 Uses and importance of Lichens
i. Lichens are used by scientists to show changes in the environment, such as air pollution,
ozone depletion, and metal contamination.
ii. They have also been used to make dyes, perfumes, and herbal medicines.
iii. Some Lichens produce natural antibiotics that kill bacteria. Humans have used these
compounds as natural antibiotics.
iv. Extracts from many Usnea species were used to treat wounds in Russia in the mid-
twentieth century.
v. Lichens provide mode of survival in harsh environments where Algae cannot normally
survive.
vi. Lichens can provide us with valuable information about the environment around us. Any
heavy metals of carbon or sulphur or other pollutants in the atmosphere are absorbed into
the Lichens thallus.
vii. Scientist can extract toxins & determine the levels that are present in our atmosphere.
6.7 Classification of Lichens
Classification based on growth forms with three principal groups identified. They are;
a. Crutose Lichens, b. Foliose Lichens and c. Fructicose Lichens.
43.
44.
45. Chapter 7
8.0 BRYOPHYTA
Bryophyta are seedless plants [Cryptogamia]. They are the oldest living plants on this planet.
They are the simplest group of embryo-bearing plants [sub-kingdom embryophyta], but have no
vascular tissue [1, 2, 3].
7.1 Characteristics of Bryophyta
i. Bryophytes are perhaps the first terrestrial plants having autotrophic mode of nutrition.
ii. They are small multicellular green plants, which inhabits in the shady and damp places.
iii.Some Bryophytes have flat green thalloid body, (liverworts and hornworts). While others
like mosses have a body which is differentiated into stem leaves and rhizoids. Rhizoids
are rootless like structures.
iv.They are non-vascular plants i.e. xylem and phloem are absent.
v. Water is required for fertilization thus Bryophytes are called amphibians of the plant
world.
vi. Sex organs are multicellular and embryo is formed after fertilization therefore,
Bryophytes are called amphibians of the plant world.
vii. The body is either thalloid [undifferentiated plant body] or a differentiated leafy plant
body.
vii. In differentiated body, the stem has weak constructions without tissue for conduction
of water. They are small and restricted to humid regions.
viii. Leaves are small (less than 12mm), petiolate [a stalk attaching it leaf blade to the
stem] and with or without costa mid-rib. The leaves are 1-cell thick, thin and flably,
except at the mid-rib with many layers thick. The leaves are not cuticle.
ix.They are attached to subtraction by the thin and slender Rhizoids.
x. The vegetative reproduction is peculiar to the plants as any detached parts can regenerate
into new plants. However a specialized structure called Gemma (e) is for vegetative
reproduction. It gets detached from the mother plant [1, 2, 3].
xi.They are small plants that can be observed and identified with hand lens. However some
can be seen with naked eyes.
46. 7.2 The three classes of Bryophytes
1. Mosses examples are Ulota phyllantha, Funaria and Polytrichum.
2. Liver worts examples are Porella platyphylla, Plagiochila aspleniodes, Riccia and
Merchantia and leafy liverwort.
3. Hornworts example is Anthoceros agrestis [1, 2, 3].
Figure 7.2a Moss, Liverwort and Hornwort
Figure 7.2b Marchantia
47. Figure 7.2c Funaria
7.3 Differences between liverworts and mosses
Liverworts Mosses
1. Gemophyte is a flattened structure
varying from a thalloid to a leafy shoot
Gematophyte is a leafy shoot more
differentiated than in liverworts
2. Rhizoids are unicellular Rhizoids are multi-cellular
3. Leaf-like structures are three in whorls Leaf-like structures are spirally arranged
4. Capsule of the sporophyte splits into four
values for dispersing into the spores
Capsule of the sporophytes does not have an
elaborate mechanism for dispersal of seeds
5. Examples include; Riccia, Machantia etc. Examples include; Funaria, Sphagnum and
Anthoceros.
48. 7.4 Importance of Bryophytes
i. Mosses are used as bedding.
ii. Mosses are used for packing.
iii. Mosses are used for padding materials due to their soft and absorbent nature.
49. Chapter 8
8.0 PTERIDOPHYTA (FERNS)
Pteridophytes are chlorophyllous, autotrophic embryophytic and tracheophytic cryptogams. They
are the non-flowering plants possesing vascular tissues. Hence, they are called Vascular
Cryptogams. They are flowerless plants that have feathery or leafy fronds and reproduce by
spores released from the underside of the fronds [1, 2, 3]. Ferns have a vascular plant system for
the transport of water and nutrients.
8.1 Characteristics of Pteridophyta (Ferns)
i. Pteridophyta are the first terrestrial vascular plants.
ii. They have well differentiated body comprising of roots stems and leaves.
iii. They inhabit mainly in shady and damp places.
iv. They possess xylem and phloem (vascular system).
iv. Pteridophytes do not produce flowers and are seedless.
v. They have highly specialized stem, root and leaves.
vi. They have well defined vascular system.
vii. They reproduce by spores.
viii. There is alternation of generation.
ix. They terrestrial mostly are found in temperate region of the world.
x. Leaves arise from rhizome.
xi. Sporangia are borne on the leaves in groups called sorus.
Examples are; Horsetails, Equisetum, Marsilia, Azolla, Mosses, Lycopodium and
Salliginella, Pteris [1, 2, 3].
8.2 Types of Ferns
The four (4) types of ferns include
8.2.1 Boston Ferns: These are the most popular of the house plant varieties, although they also
grow wild outdoors in many regions. They have dark green leaves with many deep, evenly
spaced indentations in the edges.
8.2.2 Holly Ferns: This variety has three to four inch dark green leaves that resemble those on
holly bushes and are heat, light and water tolerant. They are available in three species including
Japanese.
50. 8.2.3 Maidenhair Ferns: As one of the most delicate types of indoor ferns, this unique plant has
thin black stems and small dainty leaves. They grow well in the corner because they cannot
survive in direct sunlight.
8.2.4 Stag horn Ferns: The plant has two sets of fronds, the green fronds are fertile, resemble
stag horns, have spores on their underside and grow up to four feet long.
8.3 Importance of Ferns
Ferns belong to the first tropic level of various food chains/webs in the biosphere as they are
considered producers .Below are some of the importance of ferns;
i. Ferns are used for ornamental purpose.
ii. Ferns are a source of food.eg.(pako) in Philippines.
iii.
iv. Tropical species of ferns are used as pot plant [1, 2, 3].
Figure 8.0 Ferns
51. Chapter 9
9.0 ANGIOSPERMS AND GYNMNOSPERMS
9.1 Gymnospermae
Gymnosperms are phanerogams or spermatophytes without ovary and fruit [1, 2, 3]. The seeds
are naked without a fruit wall. E.g. Cycas, Pinus, Cactus, Gnetum.
Figure 9.1a Cycas Figure 9.1b Cactus
9.2 Characteristics of Gymnospermae
i. They do not have an outer covering or shell around their seeds.
ii. They do not produce flowers.
iii. They do not produce fruits.
iv. They are pollinated by the wind.
v. Vessel are absent except order Gnetales act as connecting link between gymnosperms and
Angiosperm.
vi. Smallest archegonium of plant kingdom is present in this group.
vii. Ovule its generally orthotropous, unitegmic with three layers [1, 2, 3].
9.3 Angiospermae
Angiosperms are the flowering plants in which the seeds are enclosed by fruits. The angiosperms
are divided into two classes: the dicotyledons and the monocotyledons.
9.4 Characteristics of Angiospermae
a. They belong to the phylum angiospermophyta
b. They have fruit to protect their seeds.
52. c. The fruit also appeals to some animals.
Examples of angiosperm are Mango, Guava and Pear trees.
.
Figure 9.4a Mango tree Figure 9.4b Guava fruit
Figure 9.4c Pear fruits
9.5 Characteristics of Monocotyledons
i. They are one seeded plant.
ii. The leaves of monocotyledons have parallel veins.
iii.They are herbaceous plants.
iv.The parts of the flowers of monocotyledons are arranged in threes or more. It may
53. contain flowers with three petals, flowers with six petals and the stamens also follow this
pattern.
v. Monocotyledons make a seed with a seed coat e.g. grass, corn, rice, wheat, etc.
vi.The leaves of monocotyledons have parallel veins[1, 2, 3].
vii. They are herbaceous plants.
9.6 Characteristics of Dicotyledons
They are two seeded plant.
The leaves of dicotyledons have veins in network.
Dicotyledons seeds also contain an embryonic plant.
The flowers of dicotyledons have petals and other parts of flower are arranged in four or
five or six. It may contain flowers with four petals, flowers with five petals, flowers
have six petals and the stamens also follow this pattern.
The seed is protected by a seed coat. E.g. trees, sunflower, rose, etc [1, 2, 3].
9.7 Differences between Gymnosperms and Angiosperms
Gymnosperms Angiosperms
1. The reproductive structures are cones
which are unisexual.
The flowers are the reproductive organs and
they may be both unisexual and bisexual.
2. The ovules are exposed, i.e., they are
not located in the ovary.
The ovules are enclosed in the ovary.
3. After fertilization, the ovules develop
into naked seeds.
After fertilization, the ovules develop into
seeds inside the fruit.
4. The microspores and megaspores are
produced by male and female cones.
The microspores are produced in anthers
while the megaspores are produced in ovules
of the ovary in flowers.
5. The pollen grains fall and germinate
directly on the micropyle of the ovules.
The pollen grains fall on the stigma,
germinate and the pollen tube carries the male
gamete to the ovary.
6. Fertilization is simple. Fertilization is double.
7. Endosperm is haploid. Endosperm is triploid.
54. 8. The pollination is by wind alone. Different agents like wind, insects, bats etc
are involved in pollination.
9. In gymnosperms, generally the xylem
contains only tracheids. Vessels are
absent.
Angiosperms vessels are always are present.
10. The phloem has no companion cells. Companion cells are present.
Figure 9.7 Gymnosperms and Angiosperms
55. Chapter 10
10.0 FORMS AND FUNCTIONAL ADAPTATION OF PLANT TO ECOSYSTEMS
An ecosystem is a community of living organisms (plants, animals and microbes) in conjunction
with the non living component of their environment (things like air, water and mineral soil),
interacting as a system. These biotic and abiotic components are regarded as linked together
through nutrient cycles and energy flows [4, 5].
10.1 Classes of aquatic ecosystem
10.1.1 Marine habitat; is made of the seas and oceans with the following characteristics;
a. Salinity is high but varies from one region to another. The average salinity is 35 parts of salt
by 1000 parts of water
b. Turbidity is high due to numerous suspended particles
10.1.2 Estuarine habitat; is a point of transition between sea and a river, with the following
characteristics;
i. There is variation of salinity due to tidal action.
ii. Turbidity is high.
iii. Water is poorly aerated.
10.1.3 Fresh water habitat: these include rivers, ponds and lakes with the following
characteristics;
a. Salinity is very low.
b. Water current is strong and swift.
Examples of plants in fresh water habitat are Water Hyacinth, Bladder wort and Water Lilly [4,
5].
56. Figure 10.1.3a Water Hyacinth
Figure 10.1.3b Bladder wort
Figure 10.1.3c Water Lilly
57. 10.2 Adaptation of plants to aquatic habitat
i. Some water plants have air storage tissues for examples water Lilly and Water lettuce.
ii. Possession of adventitious roots for examples Water lettuce.
iv. Possession of light bodies which enable them to float in water [4, 5].
10.3 Terrestrial ecosystem
A terrestrial ecosystem is an ecosystem found on land form. There are six primary terrestrial
ecosystems; Tundra, Taiga, Temperate deciduous forest, Tropical rain forest, Grass land and
Desert.
10.3.1 Grassland ecosystem
Grassland are areas where the vegetation is dominated by grasses (panacea), however sedge
(cyperaceous) and rush (juncaceous) families can also found. Grassland occurs naturally on all
continents except Antarctica with the following characteristics.
a. It consists predominantly of grasses which are usually burnt annually. The grasses form a
continuous layer of vegetation of about 1.5-3.0 meter tall.
b. Rainfall is between 75 and 125cm a year with a prolonged dry season.
10.3.2 Tropical rainforest
tropic
of Capricorn with following characteristics.
i. Presence of buttresses roots.
ii. Trees have broad leaves.
iii. Presence of tall trees.
iv. Presences of epiphytes.
10.3.3 Desert or arid habitat
Desert plants work hard to make use of what is available. They use the suns energy to convert
carbon dioxide to (CO2) and water (H20) into sugar, a process called photosynthesis with
following characteristics [4, 5].
a. Rainfall is low, about 25cm annually and the rainfall is unpredictable.
b. In desert, few plants are found around the oasis and Dry River valleys.
c. Desert plants are xerophytes and include Cactus, Cycas, Mosses, Lichens and Algae. Animals
in desert are scorpion, camel, snake etc.
58. 10.4 Features of desert plant and their adaptations
10.4.1 Waxy cover: Plants do not loose water through their pores they also lose it through the
cell walls on their leaves. The leaves and stems of many desert plants have a thick covering that
is coated with a waxy substance, allowing them to still open and absorb carbon dioxide.
10.4.2 Little leaves: Most desert plants have small leaves or no leaves at all. The smaller or
fewer leaves a plant has, the less water is lost during transpiration since it has less surface area
exposed to the sun and wind.
10.5 Marsh habitat
This is known as water logged or flooded low land habitat, it is the transition between the aquatic
and terrestrial habitat. Trees that grow in this habitat are called swamps.
10.5.1 Types of marshes
a. Fresh water marsh.
b. Salt water marsh.
10.5.2 Characteristics of marshes
i. Low land habitat.
ii. Presence of stagnant water.
iii. High flooding.
iv. Presence of organic matters.
v. Absence of trees.
vi. Soil is poorly drained and contains little oxygen [4, 5].
59. Chapter 11
11. GROWTH IN PLANTS
11.1 Growth in plants
Growth is the irreversible increase in volume (size), number part, length and weight of an
organism. All living thing have a pattern of growth inheritance from their parent. Development is
the process by which a matured multicellular organism or part of an organism produced by
addition of new cells [1, 2, 3, 4, 5].
11.2 Stages of growth in plants
There are three processes in growth in plants which include:
11.2.1 Assimilation: is the nutrient absorbed from the environment in the process of feeding.
11.2.2 Expansion: of cell is due to the increase in the protoplasm.
11.2.3 Cell division: takes place when the cell is matured.
11.3 Cell enlargement in plants
After mitosis in plant, the daughter cells absorb nutrient s from their surroundings. The nutrients
are used for respiration to generate energy, while the remaining part is assimilated as a resulting
in the enlargement of the cells .as the enlargement of the cell [1, 2, 3, 4, 5].
11.4 Cell differentiation in plants: is the result leading to the development of specialized cells
11.5 Apical growth in plants
Growth occurs in a certain tissue which is the meristems. Meristems are found in the stem, root
apex, shoot apex-base, internodes and vascular cambium. Meristem is a tissue that retains the
ability to divide by the mitosis and turn out a new cell. Growth which is initiated in the apical-
stem and apical root meristem is called apical growth [1, 2, 3, 4, 5].
11.6 Intercalary growth in plants
This is the growth occurs at the meristems of the base of the internodes and is responsible for the
development of the branching system of the stems and the roots. Growth is limited in animal and
unlimited in plant. Some animal show definite growth while plant shows indefinite.
11.7 Differences between growth and development in plants
Growth is quantitative which measured the increase in the amount of protoplasm, while
development is the observation in the changes in the nature of growth and function of organisms.
60. The qualitative changes in structure and function that go on side by side with growth in an
organism is known as development.
11.8 Differences between isometric and allometric growth in plants
All the organs that move side by side is known isometric growth, and the organ or structure in
which the rate of growth is different from the rest part of the organisms are said to show
allometric growth.
11.9 Aspects of plant growth in plants
Primary growth starts from the development of the; (i) Root hair, (ii) Root tip and (iii) Root cap.
Primary growth starts from the development of the embryo into the seedling. This is the growth
that forms the main ground tissue of the plant body. It is also the growth that gives rise to the
primary roots and shoots, which continues in the root and shoot apices to develop the main
tissues of the plant. Primary growth contains the mitotic cell division of the meristematic cells of
the shoot tips and the root in the apical growths and the lateral buds in the intercalary growth.
Secondary growth however, does not occur in herbaceous annual or biennial plants. It grows due
to the thickness in the meristematic cells which are found in-between the xylem and phloem [1,
2, 3, 4, 5].
11.10 The root tip in plants
The root tip consists of;
11.10. 1 Meristem in roots: a region of rapid mitosis, which produces the new cells for root
growth.
11.10. 2 root cap in roots: a sheath of cells that protects the meristem from abrasion and
damage as the root tip grows through the soil. Because of the frequency of mitosis in the
meristem, root tips are often used to demonstrate mitosis in the laboratory.
11.11 The region of elongation in roots
Here the cells produced by mitosis undergo a period of elongation in the direction of the axis of
the root. It is at this time that they are sensitive to gravity and respond with gravitropism.
61. 11.12 The region of differentiation in roots
Here, there are developments of the differentiated tissues of the root.
11.12.1 Epidermis. Is a single layer of flattened cells at the surface. When first formed,
epidermal cells have extensions the root hairs which greatly increase the surface area
available for the uptake of nutrients from the soil [1, 2, 3, 4, 5].
11.12.2 Cortex: A band of parenchyma cells that develops beneath the epidermis. It stores food.
Its inner surface is bounded by a single layer of cells called the endodermis.
11.12.3 Pericycle: The outer boundary of the stele. Secondary roots branch from it.
11.12.4 Xylem: Arranged in bundles in a spoke-like fashion.
11.12.5 Phloem: Alternates with xylem
11.12.6 Cambium: In older parts of the root, another meristem forms between the xylem and
phloem. Mitosis in the cambium produces new "secondary xylem" to the inside and secondary
phloem to the outside.
11.13 Water uptake in plants
Water enters the root through the epidermis. Once within the epidermis, water passes through the
cortex, mainly travelling between the cells. However, in order to enter the stele, it must pass
through the cytoplasm of the cells of the endodermis [1, 2, 3, 4, 5].
Once within the stele, water is free again to move between cells as well as through them. In
young roots, water enters directly into the xylem. In older roots, it may have to pass first through
a band of phloem and cambium. It does so by traveling through horizontally-elongated cells, the
xylem rays.
11.14 Mineral uptake in plants
One might have expected that minerals would enter the root dissolved in water. But, in fact,
minerals enter separately:
i. Even when no water is being absorbed, minerals enter freely mostly through the root hairs.
ii. Minerals can enter against their concentration gradient; that is, by active transport. For
example, plants can take up K+
from the soil against a ten-thousand-fold concentration gradient;
e.g., from as little as 10 µM in the soil to 100 mM in the cell.
iii. Anything that interferes with the metabolism of root hairs interferes with mineral absorption.
62. iv. The root hairs are also the point of entry of mycorrhizal fungi. These transport minerals
especially phosphorus to the root hair in exchange for carbohydrates from the plant.
v. In legumes, the root hairs are the point of entry of rhizobia that will establish the mutualistic
partnership enabling the plant to convert atmospheric nitrogen into protein [1, 2, 3, 4, 5].
11.15 Plants absorb their nutrients in inorganic form
For examples:
a. Nitrogen enters as nitrate (NO3 ) or ammonium ions (NH4
+
)
b. Phosphorus as PO4 .
c. Potassium as K+
.
d. Calcium as Ca2+
.
When you hear of the virtues of organic fertilizers, remember that such materials meet no
nutritional need of the plant until their constituents have been degraded to inorganic forms.
Organic matter does play an important role in making good soil texture, but only to the extent
that it can yield inorganic ions can it meet the nutritional needs of the plant.
Once within the epidermis, inorganic ions pass inward from cell to cell, probably through
plasmodesmata [1, 2, 3, 4, 5]. The final step from the cytoplasm of the pericycle cells to the
xylem is probably accomplished once again by active transport.
11.16 Gas exchange in roots
The older parts of roots are sheathed in layers of dead cork cells impregnated with a waxy,
waterproof (and airproof) substance called suberin. This sheath reduces water loss but is as
impervious to oxygen and carbon dioxide as it is to water. However, the cork is perforated by
nonsuberized pores called lenticels. These permit the exchange of oxygen and carbon dioxide
between the air and the living cells beneath [1, 2, 3, 4, 5].
63.
64. 11.17 Rate of growth in plants
i. Height or length increase of the stem root and any organ of the
ii. Increase in the girth or the circumference of the stem.
iii. Increase in area of the leaf.
iv. Increase in weight.
v. Increase in number of the stem branches.
11.18 Factors affecting growth in plants
Factors that influence plant growth are:
i. Temperature (air and soil), ii. Light (Sunlight), iii. Soil nutrients, (minerals )iv. Oxygen, v.
Carbon IV dioxide (CO2), vi. hydrogen vii. Water and viii. Hormones [1, 2, 3, 4, 5].
11.19 Epigeal and hypogeal germination in plants
Epigeal germination implies that the cotyledons are pushed above ground. The hypocotyl (part of
the stem below the cotyledon) grows, while the epicotyl (part of the stem above the cotyledon)
stays the same length. In this way, the hypocotyl pushes the cotyledon upward. Examples are
Cowpea, Pigeon pea and Soya bean. Hypogeal germination on the other hand, implies that the
cotyledons stay below the ground. The epicotyl (part of the stem above the cotyledon) grows,
while the hypocotyl (part of the stem below the cotyledon) stays the same length. In this way, the
epicotyl pushes the plumule above the ground. Examples maize wheat Sorghum, rice and
coconut [1, 2, 3, 4, 5].
Figure 11.19 Epigeal and hypogeal germination in plants
65. REFERENCES
1. Roberts, M.B.V. (2014). Biology - A Functional Approach. Roberts Oxford University
Press; 4th edition, Nelson Thornes, pp. 704. ISBN-13: 978-0174480198.
2. Roberts, M.B.V. and King, T. J. (1987). Biology: A Functional Approach. Students'
Manual. Nelson Books; 2nd Revised edition, pp. 416. ISBN-13: 978-0174480358
3. Dutta, A.C. (1998). Botany for Degree Students. Oxford University Press, pp. 724.
4. Purohit, S. S. and Agrawal, A. (2011). Ecology and Environmental Biology. Agrobios
Publisher, Vedams eBooks (P) Ltd (New Delhi, India), pp. 18. ISBN: 8177544462,
9788177544466.
5. Shukla, RS. and Chandel, P.S. (2009). A Textbook of Plant Ecology (Including
Ethnobotany & Soil Science). Chand, S. Publisher, pp. 552. ISBN: 8121905486.
