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.
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:
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a) Flowers cream-coloured; fruiting calyx enclosing the berry ……Physalis b) Flowers white or violet; fruiting calyx not enclosing the berry ….2
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a) Corolla rotate; fruit a berry …..Solanum b) Corolla funnel-form or salver-form; fruit a capsule: ….3
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a) Radical leaves present; flowers in racemes; fruits without prickles …Nicotiana b) Radical leaves absent; flowers solitary; fruits with prickles …..Datura
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.