Description of flowering plants in botanical terms in relation to taxonomy

1. RVSKVV, COLLEGE OF AGRICULTURE, GWALIOR
2020-21
ASSIGNMENT FOR PRACTICAL EXAMINATION
M.Sc. Ag. Previous Year 2nd Sem
SUBJECT- Basic Concepts in Laboratory Techniques (PGS504)
ASSIGNMENT TOPIC : Description of flowering plants in botanical terms in relation to taxonomy
SUBMITTED BY –
SHIVANI UPADHYAY
ENROLL NO. 20111611
M.Sc. Ag. Previous Year 2nd Sem
DEPT- PLANT BREEDING AND GENETICS

2. The Description of Flowers
A flower is the reproductive unit of an angiosperm plant. There is an enormous variety of flowers, but all have some
characteristics in common. The definitive characteristic of the angiosperms is the enclosed ovary, which contains and
protects the developing seeds. Floral reproduction is bisexual, and flowers have "male" and "female" parts.
The "male" or pollen-bearing part is called the stamen, and is composed of the filament and the anther.
The "female" or seed-bearing part is called the pistil, and is composed of the ovary, the stigma, and the style.
A flower may have exclusively male parts, exclusively female parts, or commonly, both.
When there are separate flower types, both may occur on the same plant; occasionally a plant may bear only male or
female flowers. Surrounding the reproductive parts is the perianth, a double envelope consisting of an outer portion,
the calyx, which forms the sepals, and an inner portion, the corolla, which forms the familiar petals. There may also
be leafy elements, termed bracts, surrounding a flower. Individual flowers are often organized into a larger group or
cluster, termed an inflorescence. The stalk supporting a single flower is called a pedicel, that supporting an
inflorescence, or an isolated flower, a peduncle.

4. Anther:
The pollen-bearing body of the stamen, usually relatively compact, and supported at the end of the narrow filament. Under
a lens, anthers exhibit a wide variety of forms and means of attachment. These characteristics are often important in
technical keys for flower identification.
Bract:
A leaf-like element below a flower or on an inflorescence. Bracts are typically shaped differently than other leaves on the
plant. They are usually green, but occasionally are brightly colored and petal-like.
Calyx:
The outer perianth of a flower. The calyx surrounds the corolla, and is typically divided into lobes called sepals. These are
frequently green, and reduced relative to the petals, but they can also be large, and brightly colored, resembling petals.
In many flowers, the sepals enclose and protect the flower bud prior to opening.
Corolla:
The inner perianth of a flower. The corolla typically surrounds the reproductive parts of the flower. It may be continuous as
in a petunia, lobed, or divided into distinct petals. In some cases, especially in cultivated varieties, the corolla may be
doubled or even further multiplied, producing multiple layers of petals. In other cases, it may be lacking entirely.

5. Filament:
The usually narrow and often threadlike part of the stamen which supports the pollen-bearing anther.
Involucre:
A circle or cup of bracts that surrounds and supports the multiple florets of the head in the composite flowers of the
family asteraceae. The shape and arrangement of the involucral bracts is important in describing the members of this
family.
Ovary:
The part of the pistil that encloses the unfertilized seeds or ovules, and that typically develops into a dry or fleshy fruit once
pollination takes place. The ovary is generally central to the flower, and supports the other principle parts. Whether they
are attached at the top (ovary inferior) or the bottom (ovary superior) is an important anatomical characteristic for
classification. Not all "fruits" are mature ovaries; some form from supporting parts of the flower, for example,
strawberries develop from the receptacle - the enlarged top of the flower stalk.
Pedicel:
The footstalk supporting a single flower in an inflorescence.
Peduncle:
The stalk supporting an inflorescence or solitary flower.

6. Perianth:
The technical term for the envelope that surrounds the reproductive parts of a flower. This enclosure is composed of two
concentric units, the outer perianth, or calyx which may be divided into sepals, and the inner perianth, or corolla, which
may be divided into petals. Either the calyx or the corolla (or both) may be much reduced or lacking.
Petal:
A division or lobe of the corolla or inner perianth of a flower.
Pistil:
The seed-bearing or "female" reproductive part of a flower. The pistil is composed of the ovary, the style, and the stigma.
The ovary contains the developing seeds, and is connected to the pollen-receiving stigma by the style. Flowers often
contain a single pistil, but may contain several. Staminate or "male" flowers contain only stamens and lack pistils
entirely.
Receptacle:
The generally enlarged top of the footstalk, which supports the other parts of the flower. Some "fruits" are enlarged
receptacles rather than ovaries.

7. Sepal:
A division or lobe of the calyx or outer perianth of a flower. Sepals are often green, and/or reduced in size, but they can be
colorful and petal-like as well.
Stamen:
The pollen-bearing or "male" reproductive part of a flower. The pollen is borne on a more or less compact body termed
the anther, which is supported by the filament. A flower may have hundreds of stamens, or only a few. Pistillate or
"female" flowers have pistils but no stamens.
Stigma:
The upper part of the pistil which receives the pollen. The stigma is often sticky, or covered with fine hairs or grooves, or
other anatomical features that help the pollen to adhere. It may be cleft into several parts.
Style:
The usually elongated part of the pistil that connects the ovary to the stigma.

8. Terms describing the inflorescence
Inflorescence refers to the flowering body of a plant. These occur in an amazing variety of forms, from solitary
flowers to enormously complex clusters, and there is an equally amazing variety of technical terminology used to
describe them. Unfortunately, as with some other aspects of botany, this terminology is not universally standardized;
different authors use different terms for the same structure, and sometimes the same terms in slightly or significantly
different ways, and classify structures using different paradigms. We only brush the surface here, making use of a few
of the most commonly used terms.
1. Solitary
2. Raceme
3. Spike
4. Corymb
5. Umbel
6. Head
7. Panicle
8. Cyme

9. What is Plant Taxonomy?
The term “taxonomy” originates from two words, “taxis” meaning arrangement and “nomos” meaning laws. Plant
taxonomy deals with the classification of plants according to certain set rules. The term taxonomy was coined by the
Swiss botanist A. P. de Candolle in his book “Théorie élémentaire de la botanique”.
Plant taxonomy can be defined as the branch of botany which deals with characterisation, identification, classification
and nomenclature of plants based on their similarities and differences.
The goals of plant taxonomy are:
1.Identification: identify the unknown species based on its characteristics and by comparing with already existing species
2.Characterisation: to describe all the characteristics of the newly identified species
3.Classification: placing and arranging the known species into different groups or taxa according to similarities and dissimilarities
4.Nomenclature: giving the scientific name according to the convention.
Taxonomy and Systematics
The word systematics comes from the word ‘systema’, meaning the systematic arrangement of the organisms. It takes into
consideration the evolutionary relationship of the organisms. Plant systematics deals with interrelation between plants and their
evolutionary descent. Systematics studies biological diversity and organises the information into a classification.

10. Organisms are categorised into different taxonomic categories according to the similarities and specific features. The
different taxonomic categories in their hierarchical order are:
•Kingdom
•Phylum
•Class
•Order
•Family
•Genus
•Species
The number of common characteristics decreases as we move from species to the kingdom, where species having
fundamental similarities and organisms in the same kingdom having least common features.
List of Systems of Plant Taxonomy
There are three main types of systems for plant classification. Here is the list of systems of plant taxonomy:
1.Artificial systems
2.Natural systems
3.Phylogenetic systems
1. Artificial systems: Artificial systems were the earliest systems, which attempted to classify organisms based on a few superficial
characters.
These were important in the history of biological classification as this was a novel attempt to organise living organisms. The demerit
was that it didn’t consider morphological details and the evolutionary relationship. They gave equal importance to vegetative and
sexual characters but it is not true. Vegetative characters are greatly influenced by the environment. As a result, the closely related
species were kept apart.
Aristotle classified plants more than 2000 years ago on the basis of simple morphological characters into herb, shrub and trees.

11. Theophrastus in his book “Historia Plantarum or Enquiry into plants” attempted to arrange plants in various groups
based on how plants reproduce and its uses. He is called “Father of Botany”.
Carl Linnaeus is known as the “Father of Modern Taxonomy”. In his book “Systema Naturae” (1735), he gave
the hierarchical system of classification of the natural world into the plant kingdom, the animal kingdom and mineral
kingdom.
He understood the importance of floral characters and classified plants based on the number of stamens present in them.
It is also known as the sexual system of classification.
Linnaeus kept on adding new work to his publications. In “Species Plantarum” (1753), he gave a brief description of
all the species known to him. He described around 7,300 plant species in it. He divided the plant kingdom into 24 classes
based on the structure, union, length and the number of stamens. E.g. Monoandria (1 stamen), Diandria (2 stamens),
Polyandria (more than 12 stamens), Monoadelphia (stamens united in a single bundle), Monoecia, Dioecia, Polygamia
(polygamous plants), Cryptogamia (flowerless plants), etc.
He gave the Binomial nomenclature system. In “Philosophia Botanica”, he had given rules for naming every species.
It is called binomial because each name has two components, genus name and species name, e.g. Solanum
melongena (brinjal), Solanum tuberosum (potato) having the same genus but different species name.
2. Natural systems: In this system of classification, more characters were considered while classifying. It was based on
the natural similarities of vegetative and floral characters among the organisms. It took into consideration various
external and internal features like the anatomy of a cell, types of embryo and phytochemistry.
Bentham and Hooker proposed the most important natural system of classification of flowering plants. They classified
plants into Cryptogams (non-flowering plants) and Phanerogams (flowering plants).

12. 3. Phylogenetic systems: This system is based on evolutionary sequence and genetic relationship. This system was developed
after the publication of Darwin’s theory of evolution. Apart from the morphological characteristics found from fossil records, genetic
constituents were also considered. It has been widely accepted by biologists all over the world. According to this system, all the
organisms belonging to the same taxa originated from the common ancestor.

13. Importance of Plant Taxonomy
•It gives a detailed overview of various morphological and anatomical structures of a plant species
•It organises all the information of plants into an orderly fashion
•It indicates the phylogenetic relationship between species and its ancestry
•Plant taxonomy enables to identify any unknown species and its place in the classification by comparing with known species
•Analysis of genetic constituents can be done on the basis of systematics
•It is used to scientifically name any species, which helps in the uniformity of the name around the world and avoids confusion
•It helps to understand the biodiversity present at a place
•It helps in recording all the living species known until now
•Taxonomy is widely used in agriculture, medicine and forestry

14. The following points highlight the ten modern trends in taxonomy of
flowering plants. The trends are:
1. Gross Morphological
2. Anatomical
3. Pollen Morphology or Palynological
4. Chemotaxonomy
5. Serotaxonomy
6. Palaeontological
7. Ontogenetical
8. Cytogenetics and Biosystematics
9. Embryology and Taxonomy
10. Numerical Taxonomy.

15. 1. Gross Morphological:
Turril says, the morphology, either of plants or animals, now days includes a good deal more than the mere study of shape.
The term ‘morphology’ is very wide and includes anatomy, and much of cytology, ontogeny, embryology, palaeontology
and genetics. He says, “even within morphology in a very strict sense the taxonomist is forced to consider matters
which involve physiology.”
Turril says, that someone or other morphological classification provides the best basis for a general classification of the
widest possible use, because morphological characters are, in general easier to use than others. According to him the great
value of a classification based essentially on gross morphology is that it enables correlations of the characters to be easily
determined.
2. Anatomical
The study of morphology with a compound microscope is known as anatomy (histology). According to some anatomists the
anatomical features are more conservative than those of-gross morphology and are, therefore, of greater use in tracing
phylogeny or organogenesis. Vesque has given much emphasis upon the value of anatomy in taxonomic and phylogenetic
research.

16. The following anatomical characters are of taxonomic significance:
1. Epidermal appendages, trichomes and emergences of all kinds.
2. Structure of stomata.
3. The wood anatomy including the elements of the
secondary xylem; this is very useful in modem taxonomic
studies, particularly in establishing the phylogenetic
relationships among taxa, and in many cases serves as an
aid in the identification of orders.
4. The nodal anatomy of the axis, the leaf trace nature.
5. Floral anatomy.

17. Epidermal emergences of all kinds:
All unicellular and multicellular appendages are known as trichomes; more massive structures, e.g., warts,
spinous bodies both epidermal and sub-epidermal are called emergences. The use of trichomes in
taxonomic studies is of much value, and has been known for many years.
In identification of some families of angiosperms, the presence of a particular type of trichomes helps a
lot, e.g., simple unicellular or multicellular uniseriate trichomes occur in many taxa; similarly the
occurrence of glandular trichomes of various kinds forms an aid to taxonomy in some respects.
Structure of stomata:
Stomata which also belong to the epidermal tissue system have been the subject matter of studies, which
is very useful in the fields of taxonomy. Stomata have been classified according to the position of
subsidiary cells, guard cells in relation to the aperture.
They are of the following types:
1. Ranunculaceous or anomocytic. Type A:
(Anomocytic = irregular celled). This type is characterised by having a limited number of subsidiary cells
which are quite alike the remaining epidermal cells; the accessory or subsidiary cells may be four or five in
number. In most of the cases, these subsidiary cells are just like the other epidermal cells. This type of
stomata occur in Ranunculaceae, Capparidaceae, Malvaceae and some other families.
2. Cruciferous or anisocytic. Type B:
(Anisocytic = unequal celled). This type of stomata occur in Cruciferae (Brassicaceae) and many genera of
Solanaceae. In this type, each stoma remains surrounded by three subsidiary cells of which one is
distinctly smaller than the other two.

18. 3. Rubiaceous or paracytic. Type C:
(Paracytic =parallel celled). In this type, the stoma remains surrounded by two subsidiary or accessory
cells which are parallel to the long axis of the pore and guard cells. This type of stomata occur in
Rubiaceae and allied families.
4. Caryophyllaceous or diacytic. Type D:
(Diacytic = cross celled). In this type each stoma remains surrounded by a pair of subsidiary or accessory
cells and whose common wall is at right angles to the guard cells. This type of stomata occurs in
Caryophyllaceae and allied families.
5. Gramineous type:
The gramineous stoma possesses guard cells of which the middle portions are much narrower than the
ends so that the cells appear in surface view like dump-bells. They are commonly found in Gramineae
(Poaceae) and Cyperaceae of monocotyledons (see fig. 8.6).

19. 3. Pollen Morphology or Palynological:
The science of palynology or study of pollen morphology deals with the detailed study of pollen grains, i.e., the
microspores of Spermatophyta, particularly of Angiosperms. It mainly deals with the structure, walls, etc., of
pollen grains. Palynological studies help in the confirmation of relationship and affinities between the related
taxa.
4. Chemotaxonomy:
The science of chemical taxonomy (chemotaxonomy) is based on the classification of plants on the basis of
their chemical constituents which are deeply concerned with the molecular characteristics. The method of
chemical taxonomy is simple in principle and is based on the investigation of the distribution of chemical
compounds, or groups of biosynthetically related compounds in series of related plants.
Different plants sometimes contain substances which although belong to different chemical compounds
appear to be biosynthetically analogous.
5. Serotaxonomy:
Serotaxonomic test and consequent phylogenetic relationships between the taxa of angiosperms were
established in Germany by Professor K. C. Mez (1866-1944) at the University of Koenigsberg in 1926, and this
was modified in 1936.
He established that relationship between larger group of angiospermic plants could be determined by
serological test; and the closely related taxa and plants could be arranged accordingly. Serotaxonomy consists
of the study and analysis of protein reaction of plants of different families with the blood serum of either
rabbit or guineapig.

20. 7. Ontogenetical:
According to Gunderson the evolution of the flowering plants is based on floral structure and presumed
organogenesis. He points out that the flowering tendencies are widely accepted as progressive in
organogenesis and agree with the findings in development.
Petals — from separate to united.
Petals — from actinomorphy to zygomorphy.
Sepals — from separate to united.
Ovary — from superior to inferior.
Carpels — from separate to united.
Placentation — from parietal to axile.
6. Palaeontological:
Darrah has proposed the following palaeontological evidences in support of the phylogenetic
evolution of the plants:
1. The invasion of land by an undifferentiated thalloid plant took place not later than Silurian.
2. The simple upright undifferentiated and protostelic axis formed in Silurian.
3. Enlargement of the plant body with specialization towards a division of labour-sterile and fertile, took
place apparently in late Silurian.
4. Origin of the photosynthetic leaf took place in Devonian.
5. Specialization in the service of support, with the resultant secondary body took place in Devonian.

21. 9. Embryology and Taxonomy:
The comparative or phylogenetic embryology deals with the embryological data, which are used as a tool
for ascertaining inter-relationships and taxonomic positions. In a symposium on comparative
Embryology of Angiosperms held at Delhi in 1967 the systematic positions of various families were
discussed in the light of embryological data.
This symposium enabled to bring together in a comprehensive manner the scattered embryological
literature on various families.
8. Cytogenetics and Biosystematics:
The branch of taxonomy principally based on cytology is known as ‘cytotaxonomy’, it is a part of
experimental taxonomy. It includes cytological aspects, study of cytogenetics and phenomeria together with
consideration of classical aspects of taxonomy.
The first step in cytotaxonomy research is the thorough sampling of the taxon (it may or may not be species)
and its populations and the consequent cytological studies of chromosomes, i.e., the number of
chromosomes, chromosome morphology, chromosome behaviour, etc., of many populations within
geographic races, species, genera and so on.
The second step consists in the capacity of different populations to hybridize and a study of vigour and
fertility of hybrids. This enables to know the presence or absence of breeding barriers between groups and is
of taxonomic value as indicating the natural limits of the taxa of various categories.
The third and last step includes the study of homologies of the chromosomes in the hybrids as determined
in the meiosis, this is significant indicator in the degree of genetic relationship. Informations obtained from
the above mentioned three steps are compared with the facts obtained from comparative morphology and
geographical distribution

22. 10. Numerical Taxonomy:
Numerical plant taxonomy may be defined as the science in which for the purpose of classifying
the plants, mathematical methods are used. In other words, the application of simple
mathematical principles or techniques or methods in taxonomical studies of plants may be
defined as numerical taxonomy.
Heywood (1967) defines numerical taxonomy as “the numerical evaluation of the
similarity between groups of organisms and the ordering of these groups into
higher-ranking taxa on the basis of these similarities.”
According to Sneath and Sokal (1973) “numerical taxonomy aims to develop methods
that are objective, explicit and repeatable, both in evaluation of taxonomic
relationships and in the erection of taxa.” Thus the establishment of this branch of
taxonomy is mainly based on the fact that the taxonomists are becoming now a days more
susceptible to more clear, more closure and more reasonable criteria and principles.
Taxometrics or numerical taxonomy is mainly concerned with procedural and operational
problems, i.e., with the actual methods we take up in classifications.
This science is based on evidence of similarities exhibited by observed and recorded characters of
taxa, not on phylogenetic probabilities. It is not concerned with producing new data but methods
of handling them by means of electronic computers so as to reduce subjective element involved in
comparing sets of data.

23. References:
• Byjus.com
• Biologydiscussion.com
• Colby.edu