Techniques, Procedures, and Stored Information that are useful in the identification and classification of organisms are called taxonomic aids. Herbaria, botanical gardens, museums, zoological parks (zoos) are important taxonomic aids used in the identification of plants and animals.
Taxonomic aids are required because the taxonomic study of plants, animals, and other organisms is basic to almost all branches of biological studies for their proper identification and finding their relationships with others.
Herbaria:
A herbarium is a place where dried, pressed, well-preserved plants specimens, mounted on sheets, properly labelled and are kept systematically according to a widely accepted system of classification. Luca Ghini set up the first herbarium and Linnaeus popularized it among botanists. The seeds, fruits, corns, and succulents (a plant such as a cactus in which the leaves and stem are thick and can store a lot of water) cannot be pressed and stored. Hence they are preserved in 2.5 % formalin.
The herbarium is a reference house which is important for future use. The specimens are readily available for reference and taxonomical, comparative, and morphological studies. Every institute teaching botany, school college or university, has a small or large herbarium. Very large herbaria are maintained by botanical gardens and institutes connected with plant systematic.
The Setting of Herbarium:
Step – 1: Plant Collection:
Rules for Collection of Specimen:
- Every student of botany is required to collect plant specimens and prepare herbarium sheets.
- All natural environments including sterile and dry must be searched.
- One may carry some small bags or envelopes to carry the seeds and other small separate components.
- Only native and naturalized plants should be collected.
- Flowers and plants can be collected from grasslands, prairies, mountains, swamps, coast, woods, surviving in the different climate and the temperature conditions which are not too extreme for the survival of the plant.
- When collecting samples from private property, or National parks, or private farms prior permission should be taken.
- If some species of plants are protected by the law. So it is not wise to pick them up. Hence it is the responsibility of the collector to check the list of the plants protected under the law in the region of collection.
- Collect only a small set of samples from a large population. Similarly, it is best to selectively trim a few pieces from different individuals so as not to damage the shrub or the tree.
- Collect the flowers in a proper season by studying the blooming times of the plants.
- Collect the samples which seem quite dry, and lacking any trace of surface moisture. But the sample plant should have the freshest appearance.
- After returning from excursion the collected specimen should be pressed and their folder should be made and to be classified.
Equipment and Material Used:
Digger and pruning knife, a sickle with a long handle, vasculum, polythene bags, magazines or newspapers, bolting papers, plant press, field notebook, herbarium sheets, glue, labels, small transparent polythene bags.
- Cutters and Scissors: used for cutting twigs.
- Digger: It is used for digging plants along with the roots.
- Plant press: It is used to press the plant for putting it on a paper sheet. Newspapers are used during pressing for support. Plant pressing can be done after returning home. But in summer time it is better to do it on the field.
- Vasculum: It is used for carrying collected specimen to avoid the loss of moisture and t avoid distortion due to drying.
- Bag: The collected specimens should be put into a strong bag made of cloth or polyethene. The bag protects the plants from damage during the outing. care should be taken that the specimens are not getting folded. A bag of proper size should be used.
- Field Notebook: Name of plant, plant habit, the habitat, the ecology, the locality, the attitude, the season, the colour of flowers, observations of stem, leaves, fruits, seeds, scents, saps, latex, uses, and related information is noted in the field notebook.
- Camera and Tripod: A good photograph of the specimen its habitat can help in studies.
Step – 2: Identification, Classification, Labelling:
This step is done after returning home from the excursion. The information should contain the scientific name of the plant, vernacular name of the plant, family of the plant, date of collection, the habitat of the plant, locality of the plant, Name of the collector and institution.
Step – 3: Pressing and Drying:
Due to the size and thickness limitations, certain branches, leaves, and bunches of flowers are required to be removed carefully. This delicate job should be carried out with the help of a knife and tweezers The retained flowers are arranged in the best possible manner so that it can show the most natural shape and all their features.
Step – 4: Special Treatments:
Some plants require special treatment for the best drying and durability. Water from cactus is to be removed using blotting papers. tubers or bulbs (as roots) of some plants must be treated before drying.
Step – 5: Mounting of Specimens on Herbarium Sheets:
Once the specimens have been dried, they are mounted on a strong mounting paper sheet to display the specimens and its data in the clearest possible way.
Step – 6: Herbarium Organization:
The mounted specimens are placed in bundles and kept together with the help of strings or straps. Each bundle should be labelled so that the seeker will be immediately able to recognize the contents of each particular group of specimens.
Step – 7: Index Register maintenance:
An index register is maintained to locate the required specimen in alphabetical order.
Important Herbaria in India:
| Name | Approx. No. Specimens | Location |
| Central National Herbarium of Botanical Survey of India | 2,000,000 | Kolkata, West Bengal |
| Forest Research Institute, Indian Council of Forestry Research and Education | 340,000 | Dehradun, Uttar Pradesh |
| Botanical Survey of India, Southern Regional Centre | 259,000 | Coimbatore, Tamil Nadu |
| Botanical Survey of India, Eastern Circle | 225,000 | Shillong, Meghalaya |
| French Institute of Pondicherry | 22,000 | Pondicherry/Puducherry |
| St. Xavier’s College, Blatter Herbarium | 200,000 | Mumbai, Maharashtra |
| Agharkar Research Institute | 28,000 | Pune, Maharashtra |
| Botanical Survey of India, Deccan Regional Centre | 11,000 | Hyderabad, Andhra Pradesh |
| Regional Herbarium of Botanical Survey of India | 12,000 | Pune, Maharashtra |
| Herbarium of NBRI | 80,000 | Lucknow, Uttar Pradesh |