Taxonomical aids: collections and keys

How do you find a name?

You see a plant that you do not know. How do you find its name? You could ask a person who knows, or look at a book with pictures. A biologist has more tools: collections of real organisms, and books with a method. These are the taxonomical aids.

Collections

Herbarium. A herbarium is a store house of plant specimens that are dried, pressed and preserved on sheets. The sheets are arranged by a system of classification that is accepted everywhere. Each sheet carries a label with the date and place of collection, the English, local and botanical names, the family and the collector's name. A herbarium is a quick reference for taxonomists.

Botanical garden. A botanical garden keeps living plants for reference. Each plant has a label with its botanical name and its family. Famous ones are the Royal Botanical Gardens at Kew (England), the Indian Botanical Garden at Howrah (India) and the National Botanical Research Institute at Lucknow (India).

Museum. A biological museum, often in a school or a college, holds preserved plants and animals for study and reference. Specimens may be kept in jars with a preserving liquid, or dried. Insects are collected, killed, preserved and pinned. Larger animals, such as birds and mammals, are stuffed. Museums often have skeletons too.

Zoological park (zoo). In a zoo, wild animals live in a protected place under human care. It lets us learn about their food habits and behaviour. The animals are given, as far as possible, conditions like their natural home.

The key

A key is a tool to identify plants and animals from their similarities and differences.

A key is built from contrasting characters, usually in pairs. Each pair is a couplet, and each statement in it is a lead. A couplet is a choice between two opposite statements: we accept one and reject the other. Then the next couplet takes us a step further, until only one name is left.

Keys are analytical: they take a group apart step by step. A separate key is needed for each taxonomic category (for families, for genera and for species).

You should find that a frog needs four answers, all "no", while a pigeon needs only one. The order of the questions decides how long the search is.

Books

• A flora is an account of the plants of an area, with their habitat and distribution.
• A manual helps to identify the names of the species in an area.
• A monograph gives all the information about one taxon, for example one genus or one family.

Try it in Python

A key is a list of questions, and a program can follow it. This program has the key to five animals. It tests the key on each animal.

Practise with new numbers

Common mistakes

• Mixing up a herbarium and a botanical garden. A herbarium holds dried plants; a garden holds living ones.
• Mixing up a museum and a zoo. A museum holds preserved specimens; a zoo keeps live animals.
• Thinking a key gives several answers. Each couplet is a choice, and the key ends in one name.
• Mixing up a flora and a monograph. A flora covers an area; a monograph covers one taxon.

Remember these

• A herbarium keeps dried, pressed plants on sheets with labels.
• A botanical garden keeps living plants with labels.
• A museum keeps preserved plants and animals. A zoo keeps live wild animals.
• A key is made of couplets of contrasting characters. We choose one lead and reject the other.
• A flora, a manual and a monograph are books. A monograph is about one taxon.

Check yourself

Try each one on your own first. If you are stuck, open a hint. Then check with Show the answer.

1. Which aid would you use to study the behaviour of a live tiger?

2. What does the label on a herbarium sheet show?

3. What is a couplet?

4. You want all that is known about the genus Solanum. Which book do you take?