Biosystematics of Angiosperms, Plant Development and Reproduction

504 Pages·2017·15.11 MB·English

MBO-06
Vardhman Mahaveer Open University, Kota

Biosystematics of Angiosperms, Plant
Development and Reproduction
MBO-06
Vardhman Mahaveer Open University, Kota

Biosystematics of Angiosperms, Plant
Development and Reproduction
Course Development Committee
Chair Person
Prof. Ashok Sharma
Vice-Chancellor
Vardhman Mahaveer Open University, Kota
Coordinator and Members
Convener
Dr. Anuradha Dubey
Department of Botany
School of Science & Technology
Vardhman Mahaveer Open University, Kota

Members
 Prof. L.R.Gurjar  Prof. T.N. Bhardwaj
Director (Academic) (Special Invite)
Vardhman Mahaveer Open University, Former Vice-Chancellor,
Kota VMOU, Kota
 Dr. Arvind Pareek  Dr. P.K. Sharma
Director (Regional Centre) Department of Botany
Vardhman Mahaveer Open University, MSJ College,
Kota Bharatpur
 Prof. B.L. Choudhary  Dr. P.P. Paliwal
Former Vice-Chancellor, Department of Botany
MohanLal Sukhadia University, Udaipur Govt. PG College, Banswara
 Prof. S.L. Kothari  Dr. Ekta Menghani
Department of Botany Department of Botany
University of Rajasthan, Jaipur JECRC University, Jaipur
 Dr. G.P. Singh  Dr. Neerja Srivastava
Department of Botany Department of Botany
University of Rajasthan, Jaipur Govt. PG College, Kota

 Dr. Vandana Sharma
Department of Botany
Govt. PG College, Kota
Editing and Course Writing
Editor
Dr. G.P. Singh
Department of Botany
University of Rajasthan, Jaipur
Writers:
 Dr. Amit Kotia 1,2,3,4  Dr. Praveen Soni 9,15,
17
Department of Botany Department of Botany
University of Rajasthan, University of Rajasthan,
Jaipur Jaipur
 Dr. Praveen Mohil 5,6,7,8  Dr. Sulekha Joshi 18,19
Department of Botany Department of Botany
University of Rajasthan, Govt. College, Kota
Jaipur
 Dr. Jitendra Kumar Verma 10,11,12  Dr. Anuradha Dubey 20
Department of Botany Department of Botany
J.D.B. Govt. Girls College, Vardhman Mahaveer Open
Kota University, Kota

 Dr. Subhash C. Verma 13,14,16
Department of Botany
P.S. B. Government P. G.
College, Shahpura, Bhilwara
Academic and Administrative Management
Prof. (Dr.) Ashok Sharma Prof. (Dr.) L.R. Gurjar Dr. Arvind Pareek
Vice-Chancellor Director Director
Vardhman Mahaveer Open Academic & Planning Material Production & Distributio n
University, Vardhman Mahaveer Open Department
Rawat Bhata Road, Kota University, Kota Vardhman Mahaveer Open University, Kota
Production: 2017 ISBN No:
All Right reserved. No part of this Book may be reproduced in any form by mimeograph or any other means without
permission in writing from V.M. Open University, Kota.
Printed and Published on behalf of the Registrar, V.M. Open University, Kota.
Printed By: Rajasthan State Cooperative Press Ltd. , Jaipur
MBO-06
Vardhman Mahaveer Open University, Kota
Index
Biosystematics of Angiosperms, Plant Development and Reproduction

Unit No. Unit Name Page No.
Unit - 1 Origin of Intrapopulation Variation and Phylogeny of 1
Angiosperms
Unit - 2 The Species Concept & Plant Nomenclature 19
Unit - 3 Biosystematics 40
Unit - 4 (Part-A) Taxonomic Evidence and Taxonomic Tools – I 58
(Part-B) Taxonomic Evidence and Taxonomic Tools - II 78
Unit - 5 Classification System of Angiosperms 97
Unit - 6 Phytogeography 120
Unit - 7 General Account of Families: I 139
(Ranales, Centrospermae and Amentiferae)
Unit - 8 General Account of Families: II 148
(Tubiflorae, Helobiales and Poales)
Unit - 9 Introduction to Plant Development and 159
Seed Germination & Growth
Unit - 10 Shoot Development 175
Unit - 11 Root Development 237
Unit - 12 Leaf Growth and Differentiation 260
Unit - 13 Introduction to Plant Reproduction 289
Unit - 14 Structure and Development of Male Gametophyte 326
Unit - 15 Structure and Development of Female Gametophyte 358
Unit - 16 Pollination, Pollen- Pistil Interaction and Fertilization 374
Unit - 17 Seed Development and Fruit Growth 413
Unit - 18 Apomixis, Polyembryony and Parthenocarpy 441
Unit - 19 Latent Life-Dormancy 464
Unit - 20 Plant Senescence and Programmed Cell Death 484
MBO-06
Vardhman Mahaveer Open University, Kota

Preface
The present book entitled “Biosystematics of Angiosperms, Plant Development
and Reproduction” has been designed so as to cover the unit-wise syllabus of
MBO-06 course for M.Sc. Botany (Final) students of Vardhman Mahaveer Open
University, Kota. The basic principles and theory have been explained in simple,
concise and lucid manner. Adequate examples, diagrammes, photographs and self-
learning exercises have also been included to enable the students to grasp the
subject easily. The unit writers have consulted various standard books on the

subject and they are thankful to the authors of these reference books.

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Unit - 1
Origin of Intrapopulation Variation and
Phylogeny of Angiosperms
Structure of the Unit:
1.0 Objectives
1.1 Introduction
1.2 Origin of Intrapopulation Variation
1.2.1 Population and Environment
1.2.2 Ecads and Ecotypes
1.2.3 Evolution and Differentiation of species-various models
1.3 Phylogeny of Angiosperms
1.3. 1 Ancestors of Angiosperms
1.3.2 Time and Place of Origin of Angiosperm
1.3. 3 Primitive Living Angiosperm
1.3. 4 Inter-relationship among the major groups of Angiosperms
1.4 Summary
1. 5 Glossary
1.6 Self-Learning Exercise
1.7 References
1.0 Objectives
After going through this unit, you will be understood about:
 the relationship between the population and environment
 Ecads and Ecotypes
 Evolution and Differentiation of species-various models
 Ancestors of Angiosperms with their Time and Place of Origin
 Primitive Living Angiosperm
 Inter-relationship of Angiosperm with other existing groups
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1.1 Introduction
The origin of species is based on the population study as we have to first learn about what
kind of population exists in the habitat as they may be of same gene pool and may be
some isolation has occured in their gene pool. After the study, the terminology viz. Ecads
and Ecotype came, and the difference is that the morphological variation disappear in
Ecads when they grow in same habitat which means that these variations are not coded
genetically (Euphorbia hirta) where as in Ecotype, the variations do not disappear as the
characters are coded genetically (Potentilla glandulosa).
This population isolation mechanism resulted in development of new species as the
characters have been genetically modified and the speciation process is initiated. There are
two methods of speciation viz. Allopatric and Sympatric patterns. Scientists described
different models and concepts of species which help in underatanding the species at
different levels like- The Biological Species Concept is the concept of species reflecting
about the species that a population or series of populations those freely interbreeding here
organisms reproductively isolated from other such population.
The origin of Angiospems is a massive subject to study and there are some lacunas to
correlate the origin of Angiosperm because the fossil record has not provided conclusive
information about the origin of angiosperms. But modern science has some how
concluded the relation of the major groups and their phylogeny and where they have
arisen. Some fossil records show their origin or relation with Pteridospermales,
Bennettitales, Cycadales and Pentoxylanean group whereas some botanist show the
affinities and origin of Angiosperms with lower group and primitive Angiospems like
Ephedrales, Gnetales, Amentiferae, Ranalesccc, and Isoetalean members.
The time of origin of Angiosperm is not clear as they suddenly appeared in the Cretaceous
period and since this age, angiosperms have became dominant vegetation on the earth.
Even the place of origin is also described by different botanist like according to Seward
(1931) the Arctic region, Smith (1970) located in South-East Asia, Retallack and Dilcher
(1981) believed origin in the Rift valley system adjoining Africa and South America. The
primitive living Angiospers are belong to some families this includes Winteraceae,
Magnoliaceae, Degeneriaceae, Himantandraceae, Eupomatiaceae, Annonaceae,
Canellaceae, and Myristaceae belongs to the orders Magnoliales. Austrobaileyaceae,
Amborellaceae, Monimiaceae and Calycanthaceae belong to the order Laurales and in the
order Trochodendrales with the famalis Trochodendraceae and Tetracentraceae. Some
other like orders Piperales, Nymphaeales, Illiciales and Ranunculales also reported
primitive members.
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1.2 Origin of Intrapopulation Variation
1.2.1 Population and Environment
Generally, the population is defined in different ways for different purposes. Population is
the group of individuals which are common to appear. The definition which is used
largely by taxonomists is “The group of individuals considered to gene-pool together at
any one time because of the features they share in common.” It means that the group of
plants, growing together, which look similar or a series of such plants which grow in a
particular area. Usually in population genetics, the co-habitation of the particular group of
individual allows them to exchange their genes. Therefore a breeding population can be
defined as “a group of individuals less degree with of crossing and with consequent gene
flow”. Two points should be noted here
(i) Possibility of inter breeding
(ii) Genetic similarity
The population is not defined on the basis of morphological characteristics especially at
gene level. Population is that in which the individual members share gene and become
inbreeding there by sharing a common gene pool.
Sirels (1951) categorized population in two distinguished group as Plurispecific and
Unispecific population. The Plurispecific population is constituted by the plants, animals
and microorganisms which are living together in the same habitat. The area for that
population may be a square yard, a square mile, a wood piece or an ant heap. Besides this,
unispecific population is a group of individuals belonging to the same species and living
in the same habitat. The populations always remain subjected to change as they can vary
in size, composition and area. They may increase or decrease in size.
Several experiments by different workers have been performed on population-
A) Turesson’s Experiment : Turesson was mainly concerned with the differentiation of
population in different ecological condition. The genetical morphological and
physiological nature of population samples from different parts are collected and
grown in uniform condition in his experimental garden at “A karp” in Sweden. He
noted the reaction of plant in cultivation over the year in term of habit, height and
flowering time etc. and found that in some cases the difference noted in the field
disappeared in other cases and the differences showed intergraduation, but in most
instances they persisted. He showed that the genetically different races were often
correlated with habitat differences and that similar selective forces in the habitat
appeared to produce similar kinds of adaption in different species. The term ‘ecotype’
was applied to these products of reaction between the genotype and the habitat.
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B) Clausen, Keck and Hiersey’s experiment: All these botanists are known for their
transect experiment which consists of the gene ecological studies of populations of
various species including Potentilla glandulosa (Rosaceae) and Achittea milkfolium
(Asteraceae).
A transect was taken across Central California for climatic differences. Experimental
gardens were established at varying altitude from about 30 meters to 500 meters, and
3300 meters and were maintained free from weed. These were extended for more than
30 years indicating the scope of the investigation. Populations of the species
mentioned above were grown at various altitudes and their responses to climate
conditions were noted. There was a superficial resemblance or parallelism in
morphological as well as physiological features in the ecotype adapted to similar
climatic conditions. Hybrids between the ecotypes were shown to be fully fertile and
could produce new genotypes with new adaptive features.
Both these experiments clearly indicated that interaction between habitat and genotype
could apparently produce ecotype.
C) Gregors’s Experiment: Similar investigations were undertaken by Gregor and his co
workers at the Scotissh Society for the Research in Plant Breeding. They called these
investigators experiment taxonomy and its practical procedures were studied by
Gregen, Dowey and Long (1936). They regarded orthodox experimental taxonomy as
complementary. They had grown the races under uniform environmental conditions in
the experimental garden so that the variation shown by races could be studied
unaffected by the irregularities of their natural habitat. They worked on the races of
Plantago maritina (Plantaginaceae) and concluded that the pattern of ecotype
variation was more frequently continuous than discontinuous corresponding to
gradients shown by the habitats.
D) Russion school: The Russion school is an important school of gene ecological studies.
It is developed under supervision of Dr. Sinka Ja (1948) of the Institute of Plant
Inducting at Leningrad.
He was responsible for much of the work on ecotype recognition. The Russian
approach differs in same respect from those of other school and has paid great
attention to geographical and zonal variability of population in wild and cultivated
plant (Onobrychis).

Four vertical belts of population may be distinguished.
1. High mountain belt
2. Middle mountain belt
3. Sub mountain belt
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