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INTRODUCTION TO PLANT TAXONOMY
(Systematic botany)
What is Plant Taxonomy?
Plant taxonomy is the science that finds, describes,
classifies, identifies, and names plants. It thus is one of the
main branches of taxonomy.
Plant taxonomy is closely allied to plant systematics, and
there is no sharp boundary between the two. In practice,
"plant systematics" is involved with relationships between
plants and their evolution, especially at the higher levels,
whereas "plant taxonomy" deals with the actual handling of
plant specimens.
Taxonomy is a science which includes identification,
nomenclature and classification of objects ( biological origin).
- G. H. M. Lawrence. When the taxonomy is concerned with
plants it is called as systematic botany.
"Classification of Organisms basing on totality of their
similarities and differences"
Plant Taxonomy is a synthesis of the following related field:
1.
2.
3.
4.
Systematic Botany
Taxonomic System
Nomenclature
Documentation
Identification: Determination of a taxon* as being identical
with or similar to another and already known element.(*
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each unit of classification is termed as taxon: Plural is
taxa).
Nomenclature: System of naming plants (i.e. Methods or
ways of giving names to plants)
Classification: is the arrangement i.e. placing of a plant or
a group of plants in a series of groups or categories
according to a particular system and in accordance with the
rules of nomenclature.
Latin name = Scientific name. Name of any plant is given in
two parts, e.g. Pinus wallichiana. Here the first name is the
generic (genus) name and the second name is the specific
(species) name. This type of naming (nomenclature) is called
as binomial system of nomenclature. (Latin names are
always represented in italics or in addition underlined)
Species: is the basic unit of classification (or a group of
individuals alike in essential particulars or sub divisions of a
genus).
Genus: is formed of species which are similar to each other.
Like wise similar genus give rise to family: families to order:
orders to class and classes to division.
Units of classification (with examples)
Kingdom
:
Sub kingdom
:
Division (=Phyllum) :
Sub division
:
Plant kingdom
Embryophyta (the embryo plant)
Tracheophyta (the vascular plant)
Pteropsida (the ferns and seed plants)
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Class
Sub class
Order
Family
Genus
Species
:
:
:
:
:
:
Angiospermae (flowering plant)
Dicotyledonae (2 cots in embryo)
Rosales
Rosaceae
Prunus
ceresoides
STRUCTURE OF HIERARCHY
1.
2.
3.
4.
5.
6.
7.
Species (Basic unit)
Genus
(Pl. Genera)
Family
(ends in 'aceae')
Order
(ends in 'ales')
Class
Division
Plant Kingdom
SUBDIVISIONS FOR THE CONVENIENCE (Examples)
SUBDIVISIONS










Suborder
Subfamily
A tribe
Subtribe
Subgenus
Subspecies
Variety
Subvariety
Form
Clone
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ENDING IN
'ineae'
'oideae'
'eae'
'inae'
as Eurosa or Section
as ssp
(var)
(subvar)
(f)
(cl)
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Why to study taxonomy?
1. Classify all kinds of plants under plant kingdom
2. To identify, name and arrange the plants in a recognized
system of classification showing phylogeny and relationship
among groups of plants.
3. Study of distribution of plants and their habitat- character.
4. Organized reconstruction of the plants kingdom including
changes in nomenclature.
Types of classification
1. Artificial
2. Natural and
3. Phylogenetic
Artificial system: This classification is based on one or few
superficial characters only. Eg. plants are grouped into herbs,
shrubs, under shrubs and trees based on habitat character.
Linnaeus system of classification is purely an artificial one
based on sexual character.
Natural system: In this system several common and constant
characters are taken into consideration. Benthem and
Hookers system of classification is one of the most
commonly used in this categories.
Phylogenetic system: Classified according to evolutionary
sequence. It also reflects the genetic relationships. Engler
and Prantle's system and Hutchingson's system of
classifications are some examples in this category.
INTERNATIONAL CODE OF BOTANICAL
NOMENCLATURE (ICBN), Recognised twelve main ranks:
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01.
02.
03.
04.
05.
06
07.
08.
09.
10.
11.
12.
Plant Kingdom
Division
Class
Order
Family
Tribe
Genus
Section
Series
Species
Variety
Form
GENERIC NAMES


Always begin with a Capital Letter
Always a noun
(e.g. Pinus roxburghii)
Origin of Generic names:
1.
Honour of Botany or Horticulture Patron; Examples







Candollea
Einsteinia
Gravia
Hookera
Jeffersonia
Linnaea
Theophrasta
Augustin de Candolle
Albert Einstein
Asa Gray
Hooker
Thomas Jefferson
Linnaeus
Theophrastus
2. Generic names express some features of a plant:
Examples

Callicarpa
Beautiful fruit
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
Oxydendrum
Sour tree
3.
Fanciful or poetic:
Example

Dodecatheon
Twelve gods
4.
Aboriginal origin:
Examples


Nelumbo
Tsuga
Ceylones
Japan
SPECIFIC NAMES
A.
Usually descriptive adjective
How it is named? Various ways depending on the Authors:
Examples
1.
Colour




alba
flava
nigra
viridis
2.
Habitat





aquatica in water
arvensis in field
muralis
on wall
palustries in swamps
sylvatica in woods
3.
Region
White
Yellow
Black
Green
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






anglicus English
canadensis
Canadian
bhutanica Bhutan
gallica
French
nepalensis
Nepalese
mexicana Mexican
zeylanica Ceylonese
4.
Size, shape and habit








alta
Tall
crassa
Thick
gigantia Giant
nataus
Swimming
pendulus Hanging
repens
Creeping
scandens Climbing
fencies
Thin
5.
Utility




edulis or esculenta edible
hortensis
grown in garden
officinalis
sold in market
sativus
sown for crops
5.
Others







autumnalis
biennis
foetida
hiberna
religiosa
spinosa
toxicaria
of Autumn
biennial
ill-scented
of winter
religious
spiny
poisonous, etc.
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6.
Relative abundance


rara
vulgaris
B.
In honour of renowned botanist

roxburghii
C.
Indicate affinity and resemblance

amaranthoides similar to Amaranthus
D.
Refer to distinctive features of the plant




angustifolia
cordifolia
grandiflora
latifolia
rare
common
narrow-leaved
heart-shaped leaved
large-leaved
broad-leaved
Citation and Authority


Solanum tuberosum L.
Asystasia gangetica T.
(Linnaeus)
(Thomas Anderson)
When there are similar names


Robert Brown
R.Br.
William Brown Wm.Br.
When father and son, both are Authors

William Hooker (Father)
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Hook.
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 Joseph Dalton Hooker (son)
(F=filius=son)
Hook.f.
When father, son and grandsons are authors
Augustin de Candolle (father)



Augustin DC.
Alphones A. DC.
Casimer C. DC.
Proposal made by one author and publication made by other
than him.

Acer oblongum Wall. ex DC.
When there is change of Taxonomic ranks and position

Medicago polymorphic L. Variety orbicularis L
Medicago orbicularis (L) All (Rank changed by Allioni)

Malva rosea L.
Althea rosea (L) Cav. (Position/genus changed by
Canavilles)
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