Introduction to plant taxonomy (Systematic botany) What is Plant Taxonomy? Plant taxonomy




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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. Systematic Botany

2. Taxonomic System

3. Nomenclature

4. Documentation


Identification: Determination of a taxon* as being identical with or similar to another and already known element.(* 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 : Plant kingdom

Sub kingdom : Embryophyta (the embryo plant)

Division (=Phyllum) : Tracheophyta (the vascular plant)

Sub division : Pteropsida (the ferns and seed plants)

Class : Angiospermae (flowering plant)

Sub class : Dicotyledonae (2 cots in embryo)

Order : Rosales

Family : Rosaceae

Genus : Prunus

Species : ceresoides


STRUCTURE OF HIERARCHY
1. Species (Basic unit)

2. Genus (Pl. Genera)

3. Family (ends in 'aceae')

4. Order (ends in 'ales')

5. Class

6. Division

7. Plant Kingdom
SUBDIVISIONS FOR THE CONVENIENCE (Examples)
SUBDIVISIONS ENDING IN
 Suborder 'ineae'

 Subfamily 'oideae'

 A tribe 'eae'

 Subtribe 'inae'

 Subgenus as Eurosa or Section

 Subspecies as ssp

 Variety (var)

 Subvariety (subvar)

 Form (f)

 Clone (cl)



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:
01. Plant Kingdom

02. Division

03. Class

04. Order

05. Family

06 Tribe


07. Genus

08. Section

09. Series

10. Species

11. Variety

12. 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 Augustin de Candolle

 Einsteinia Albert Einstein

 Gravia Asa Gray

 Hookera Hooker

 Jeffersonia Thomas Jefferson

Linnaea Linnaeus

 Theophrasta Theophrastus
2. Generic names express some features of a plant: Examples
 Callicarpa Beautiful fruit

 Oxydendrum Sour tree


3. Fanciful or poetic: Example
 Dodecatheon Twelve gods
4. Aboriginal origin: Examples
 Nelumbo Ceylones

 Tsuga Japan


SPECIFIC NAMES
A. Usually descriptive adjective
How it is named? Various ways depending on the Authors: Examples

1. Colour


 alba White

 flava Yellow

nigra Black

 viridis Green


2. Habitat
 aquatica in water

 arvensis in field

 muralis on wall

 palustries in swamps

sylvatica in woods
3. Region
 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 of Autumn

 biennis biennial

 foetida ill-scented

 hiberna of winter

 religiosa religious

 spinosa spiny

toxicaria poisonous, etc.
6. Relative abundance
 rara rare

 vulgaris common


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 narrow-leaved

 cordifolia heart-shaped leaved

 grandiflora large-leaved

 latifolia broad-leaved


Citation and Authority
 Solanum tuberosum L. (Linnaeus)

 Asystasia gangetica T. (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) Hook.

 Joseph Dalton Hooker (son) Hook.f. (F=filius=son)


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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