Taxonomic Aids

Taxonomic Aids

Taxonomic aids are the tools for the taxonomic study. Some techniques, procedures and stored information that are useful in identification and classification of organisms are called taxonomical aids. They are required in almost all branches of biological studies for their proper identification and for finding their relationship with others. Some of the taxonomical aids are keys, flora, revisions, monograph, catalogues, herbarium, botanical gardens etc.

1. Keys

Taxonomic keys are the tools for the identification of unfamiliar plants. These keys are based on characters which are stable and reliable. The most common type of key is a dichotomous key. It consists of a sequence of two contrasting statements. A pair of contrasting statements is known as couplet. Each statement is known as lead. The plant is correctly identified with keys by narrowing down the characters found in plant.

Example:

Another type of key for identification is the Polyclave or Multi-entry key. It consists of a list of numerous character states. The user selects all states that match the specimen. Polyclave keys are implemented by a computer algorithm.

2. Flora

Flora is the document of all plant species in a given geographic area. Flora consists of total number of plant species in an area and gives information about flowering season, fruiting season and distribution for the given geographic area. It also provides details on rare and endemic species of that area. Example: Flora of Tamil Nadu Carnatic by K.M.Matthew. Floras are categorized based on the scope and area covered.

Local Flora

It covers the limited areas, usually state, country, city or mountain range. Example: ‘Flora of Thiruvannamalai District’ by R. Vijaysankar, K. Ravikumar and P. Ravichandran.

Regional Flora

It includes large geographical area or a botanical region. Example: ‘Flora of Tamil Nadu’ Carnatic by K.M.Matthew (1983), ‘Flora of Madras Presidency’ by J.S. Gamble and Fischer.

Continental Flora

This flora covers the entire continent.

Example: ‘Flora of Europaea’ by D.A.Web.

Electronic Floras (e - floras)

It is nothing but the digitized form of a flora published online. Example: ‘e – Flora China’. This provides the information and also functions as an identification tool.

3. Monograph

A Monograph is a complete global account of a taxon of any rank – family, genus or species at a given time. This includes the existing taxonomic knowledge and all relevant information about the group concerned such as Anatomy, Biochemistry, Palynology, Chromosome Number and Phylogeny. It also includes extensive literature review, all nomenclatural information, identification key to all taxa, citation of specimens examined and distribution map.

Example: The Family Lentibulariaceae by Peter Tylor.

Revisions

Taxonomic revision is carried out for a family or genus. Usually taxonomic revision is less comprehensive than a monograph for a given geographical area. Revisions normally incorporate keys to identify the taxa, short descriptions, often confined to diagnostic characters, distribution maps and a classification. Illustrations mostly in the form of line drawings are included both in monographs and revisions. There are difficulties in identifying various members within a taxon. If there is inconsistency of the characters within the taxon’s geographic range then a revision is needed. Taxonomic revisions are primarily based on original research work. Example: Malvaceae of India by T.K.Paul, Venu. P. 2006 Strobilanthes (Acanthaceae) in Peninsular India.

Catalogues

Catalogues are the books of libraries rich in botanical titles. They have special value in taxonomic studies. To refer a catalogue, one should know full name of the author, exact title of the book, exact date of publication the particulars of edition.

Example: Catalogue of the Library of British Museum (of Natural History) Catalogue of the Library of the Massachusetts Horticultural Society.