Biyani's Think Tank Taxonomy and Embryology of Angiosperm B.Sc. Part-III

75 Pages·2013·2.53 MB·English

Biyani's Think Tank
Concept based notes
Taxonomy and Embryology of
Angiosperm
B.Sc. Part-III

Dr Ruby
Deptt. of Scienge
Biyani Girls College, Jaipur
2

Published by :
Think Tanks
Biyani Group of Colleges

Concept & Copyright :
Biyani Shikshan Samiti
Sector-3, Vidhyadhar Nagar,
Jaipur-302 023 (Rajasthan)
Ph : 0141-2338371, 2338591-95 Fax : [phone]
E-mail : [email protected]
Website :www.gurukpo.com; www.biyanicolleges.org

Edition : 2012

While every effort is taken to avoid errors or omissions in this Publication, any mistake or
omission that may have crept in is not intentional. It may be taken note of that neither the
publisher nor the author will be responsible for any damage or loss of any kind arising to
anyone in any manner on account of such errors and omissions.

Leaser Type Setted by :
Biyani College Printing Department
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Taxonomy and Ebbryology 3

Preface

I

am glad to present this book, especially designed to serve the needs of the students.
The book has been written keeping in mind the general weakness in understanding the
fundamental concepts of the topics. The book is self-explanatory and adopts the “Teach
Yourself” style. It is based on question-answer pattern. The language of book is quite easy and
understandable based on scientific approach.
Any further improvement in the contents of the book by making corrections, omission and
inclusion is keen to be achieved based on suggestions from the readers for which the author
shall be obliged.
I acknowledge special thanks to Mr. Rajeev Biyani, Chairman & Dr. Sanjay Biyani, Director
(Acad.) Biyani Group of Colleges, who are the backbones and main concept provider and also
have been constant source of motivation throughout this endeavour. They played an active role
in coordinating the various stages of this endeavour and spearheaded the publishing work.
I look forward to receiving valuable suggestions from professors of various educational
institutions, other faculty members and students for improvement of the quality of the book. The
reader may feel free to send in their comments and suggestions to the under mentioned
address.
Author

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4

Section-A
Taxonomy
Q.1 Classification of Angiosperm with special reference of Linnaeus, Bantham and
Hooker?
Ans. ANGIOSPERM CLASSIFICATION
The classification of angiosperms is still very controversial, and two schemes are
presented here – the first (B&H) as a means to LEARNING the families, the
second (APG) as a presentation of the rudiments of an agreed EVOL UTIONARY
TREE. Historically a number of schemes have been produced. Bentham &
Hooker's Genera Plantarum (1862-1883) – comprising 200 families and 7,569
genera – pre-dated the publication of Charles Darwin‘s Origin of Species, so this
is essentially a non-evol utionary scheme. However, the arrangement of families
was based on characters which provided a sequence fr om what they took as the
most primitive to the most derived families – the Scalae Naturae.
The classification was based on few, essential characters, and as a result is highly
predictive – examination of these characters will place an unknown specimen into
a particular category. The Angiosperm Phylogeny Group (APG): Systematic
research over the past 150 years has changed our view of plant classification,
especially in the last 10 years, when major advances in DNA sequencing have
provided a completely new ave nue of approach. Numerous classifications and
schemes have been published: Hutchinson (328 families), Cronquist (388),
Takhtajan (592) Dahlgren (477), Thorne (454) Brummitt (445), and Reveal (612),
each differ in the recognition of families and the overall scheme. As a result, fam
ilies, orders and sub-classes are not comparable between any of these systems.
Molecular studies are by no means final, and, contrary to what many reference
books and journals might imply, a modern synthesis is far from stabilised.
However, a consensus is now beginning to emerge. The combin ed work of many
scientists under an umbrella grouping known as the Angiosperm Phylogeny
Group (APG) has produced the rudiments of an agreed evolutionary tree.
Bentham and Hooker
George Bentham and Joseph Dalton Hooker - Two English taxonomists who were
closely associated with the Royal Botanical Garden at Kew, England have given a
detailed classification of plant kingdom, particularly the angiosperms.
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Taxonomy and Ebbryology 5

Fig. - Taxonomists: Bentham and Hooker
They gave an outstanding system of classification of phanerogams in their Genera
Plantarum which was published in three volumes between the years 1862 to 1883.
It is a natural system of classification. However, it does not show the evolutionary
relationship between different groups of plants, in the strict sense. Nevertheless,
it is the most popular system of classification particularly for angiosperms. The
popularity comes from the face that very clear key characters have been listed for
each of the families. These key characters enable the students of taxonomy to
easily identify and assign any angiosperm plant to its family.
Bentham and Hooker have grouped advanced, seed bearing plants into a major
division called Phanerogamia. This division has been divided into three classes
namely:
1. Dicotyledonae
2. Gymnospermae and
3. Monocotyledoneae
1 Class :Dicotyledonae
This group includes angiosperms in which the seed bears two cotyledons and
leaves exhibit reticulate venation. It is divided into three subclasses - Polypetalae,
Gamopetalae and Metachlamydae.

Sub-class Polypetalae

The flowers contain distinct non-essential whorls calyx and corolla. In the corolla
petals are free. This sub-class includes 8 series Thalamiflorae, Disciflorae and
Calyciflorae.
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Series Thalamiflorae: Many stamens in the androecium. Flower is
hypogynous.
Series Disciflorae: Hypogynous flowers with a cushion-like disc around or
below the ovary.
Series Calyciflorae: Flowers epigynous or perigynous. Thalamus is in the form
of a cup.

Sub-class Gamopetalae
Flowers with distinct calyx and corolla. In the corolla petals are fused. This sub-
class includes 3 series.
Series Inferae: Flowers with inferior ovary.
Series Heteromerae: Flowers with superior ovary. Number of carpels - more
than two.
Series Bicarpellatae: Flowers with superior ovary. Number of carpels - two.

Sub-class Monochlamydae
The flowers are with only one non-essential whorl (perianth) or absence of non-
essential whorls. It includes 8 series.
Curvembryae: Usually single ovule, embryo coiled around the endosperm.
Multiovulate Aquaticae: Aquatic plants with syncarpous ovary and many
ovules.
Multiovulate Terrestris: Terrestrial plants with syncarpous ovary and many
ovules.
Microembryae: Only one ovule, small, tiny embryo endospermic seed.
Daphnales: Only one carpel and single ovule.
Achlamydosporae: Ovary inferior, 1 to 3 ovules - unilocular.
Unisexuales: Flower unisexual, perianth usually absent.
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Taxonomy and Ebbryology 7

Ordines Anomali: (Anomolous families) Plants with uncertain systematic
position but closer to unisexuales.
2 Class : Gymnospermae
This group includes the gymnosperms in which seeds are not enclosed in fruits.
This class is divided into three families Gnetaceae, Confiraceae and Cycadaceae.

Fig. - Angiosperm Classification
3 Class: Monocotyledonae
This group includes angiosperms in which the seed bears only one cotyledon. The
leaves exhibit parallel venation. It is divided into the following seven series.
Microspermae: Ovary is inferior, seeds are minute and non-endospermic.
Epigynae: Ovary inferior, seeds are large and endospermic.
Coronarieae: Ovary superior, perianth petalloid.
Calycinae: Ovary superior, perianth sepalloid.
Nudiflorae: Perianth reduced or absent. Seeds are endospermic.
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Apocarpae: Carpels more than one, free, seeds are endospermic.
Glumaceae: Perianth reduced or absent, scaly bracts present.

Each of the series mentioned under dicotyledonae and monocotyledonae have
been further divided into orders and families. Bentham and Hooker classified the
angiosperms into 202 families. They were able to provide distinct diagnostic key
characters to each of these families. This is the reason for the popularity of
Bentham and Hooker's classification particularly amongst the taxonomists

Microspermae: Ovary is inferior, seeds are minute and non-endospermic.
Epigynae: Ovary inferior, seeds are large and endospermic.
Coronarieae: Ovary superior, perianth petalloid.
Calycinae: Ovary superior, perianth sepalloid.
Nudiflorae: Perianth reduced or absent. Seeds are endospermic.
Apocarpae: Carpels more than one, free, seeds are endospermic.
Glumaceae: Perianth reduced or absent, scaly bracts present.

Each of the series mentioned under dicotyledonae and monocotyledonae have
been further divided into orders and families. Bentham and Hooker classified the
angiosperms into 202 families. They were able to provide distinct diagnostic key
characters to each of these families. This is the reason for the popularity of
Bentham and Hooker's classification particularly amongst the taxonomists.

Q.2 Explain concept of Binominal Nomenclature and its advantage?
Ans. Binomial nomenclature (also called binominal nomenclature or binary
nomenclature) is a formal system of naming species of living things by giving
each a name composed of two parts, both of which use Latin grammatical forms,
although they can be based on words from other languages. Such a name is called
a binomial name (which may be shortened to just "binomial"), a binomenal or a
scientific name; more informally it is also called a Latin name.
The formal system of naming species of living things is called binomial
nomenclature (especially in botany, but also used by zoologists), binominal
nomenclature (since 1953 the technically correct form in zoology), or binary
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Taxonomy and Ebbryology 9

nomenclature. This system of naming was invented byLinnaeus. The up-to-date
version of the rules of naming for animals and plants are laid out in the
International Code of Zoological Nomenclature and the International Code of
Botanical Nomenclature respectively.
The first part of the name identifies the genus to which the species belongs; the
second part identifies the species within the genus. For example, humans belong
to the genus Homo and within this genus to the species Homo sapiens. The
introduction of this system of naming species is credited to Linnaeus, effectively
beginning with his work Species Plantarum in 1753.
The application of binomial nomenclature is now governed by various
internationally agreed codes of rules, of which the two most important are the
International Code of Zoological Nomenclature (ICZN) for animals and the
International Code of Nomenclature for algae, fungi, and plants (ICN) for plants.
Although the general principles underlying binomial nomenclature are common
to these two codes, there are some differences, both in the terminology they use
and in their precise rules.

In modern usage, the first letter of the first part of the name, the genus, is always
capitalized in writing, while that of the second part is not, even when derived
from a proper noun such as the name of a person or place. Similarly, both parts
are italicized when a binomial name occurs in normal text. Thus the binomial
name of the annual phlox is now written as Phlox drummondii.

The name "Linnaeus" tells the reader who it was that named the species; 1758 is
the date of the publication in which the original description can be found, in this
case the 10th edition of the book Systema Naturae. (Botanists are not required to
give the date).

Many scientific names describe some characteristic of the organism (alba=white;
rubra=red); many are derived from the name of the discoverer or the geographic
location of the organism. Genus and species names are always italicized when
printed; the names of other taxa (families, etc.) are not.

When a species (or several species of the same genus) is mentioned repeatedly,
the genus may be abbreviated after its first mention, as in Q. alba. Subspecies are
indicated by a trinomial; for example, the southern bald eagle is Haliaeetus
leucocephalus leucocephalus, as distinguished from the northern bald eagle, H.
leucocephalus washingtoniensis.

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How To Write Plant Species Names (Binomial Nomenclature Or Scientific
Names)
1. As many of you know, common names may be the same for many
different plant species. For example, many of the species in the Opuntia
genus (contains several species) share Prickly Pear Cactus as their common
name. So how do we name all of the plants and what is a genus?

2. We use the binomial naming system (scientific name), as the name implies,
uses two words to name a particular species.

The first word we use to describe a plant is the generic name (genus). The
generic name must be capitalized when naming a species! It must also
describe the group of plants it's naming. For example, the palm genus
Trachycarpus means "Rough Fruit".

The second word we use is the specific epithet. The specific epithet must
be lower case! It does not have to describe the plant. For example, the
specific epithet for the species Trachycarpus fortunei was named after Robert
Fortune, the botanist who brought it from Asia to Europe.

To name a species we simply put the genus and specific name together
with the genus capitalized and specific epithet in lower case. Both words
must be emphasized (italic, underline) in the following format:

Genus specific epithet -> Trachycarpus fortunei
You may also see more names after species name.
One of the ranks lower than the specific epithet is the variety. A variety is
used describe a traits which are different among a population. The plant
populations of a variety are usually separated geographically but if they
are brought together, they will hybridize. The variety usually describes the
location or trait in which the variety located or describes. The variety is
abbreviated in the name as "var." and it is lower case and emphasized.
3. Another rank that is commonly confused with variety is a cultivar. A
cultivar is plant that that is either found in cultivation (not in the wild) or
bred my humans to have a specific trait. A cultivar is represented by single
quotations around the cultivar name after the specific epithet. Cultivar is
abbreviated as cv. and the description name is not emphasized.
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