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Here is a compilation of essays on ‘Herbarium’ for class 11 and 12. Find paragraphs, long and short essays on ‘Herbarium’ especially written for school and college students.
Essay on Herbarium
Essay Contents:
- Essay on the Meaning of Herbarium
- Essay on the Preparation of Herbarium
- Essay on the Techniques to Prepare Herbarium
- Essay on Important Herbaria
- Essay on the Functions of Herbarium
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Essay # 1. Meaning of Herbarium:
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Herbarium is a place of depository of plant specimens in dry condition. According to H. M. Lawrence (1967) “a Herbarium is a collection of plant specimens that usually have been dried and pressed, are arranged in the sequence of an accepted classification, and are available for reference or other scientific study”. In some cases, such as succulents and the specimens unsuitable for pressing are preserved in some preservatives like formaldehyde solution 4-5% or in F.F.A (Formyl acetic acid).
Composition of some common preservatives:
A. Formaldehyde Solution (5%):
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i. Commercial formaldehyde (40% pure) ………….. 12.5ml.
ii. Water……………………………………. 87.5ml.
[Calculate the amount of formaldehyde following the formula V1S1 = V2S2. For the preparation of 100 ml of 5% solution from 40% concentration: 100 ml x 5% = V2 x 40%. So V2 = 500ml/40 = 12.5 ml].
B. F.A.A. (Formyl Acetic Acid):
i. Commercial formaldehyde (36-40% pure) 5 ml.
ii. Glacial acetic acid 5 ml.
iii. 70% Ethanol 90 ml.
(The F.A.A. is used for long term preservation).
C. Solution to Preserve Green Colour of Plants:
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i. 50% Ethanol 90.00 ml.
ii. Commercial formaldehyde 5.00 ml.
iii. Glycerine 2.50 ml.
iv. Glacial acetic acid 2.50 ml.
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V. Cupric chloride 20.00 gm.
vi. Uranium nitrate 2.50 gm.
Essay # 2. Preparation of Herbarium:
To prepare a Herbarium following equipments and techniques are generally required:
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Equipments:
1. Secateur:
This is useful for cutting the twigs of shrubs and trees for Herbarium specimens.
2. Digger:
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The digger (Fig. 4.1 A) is used to take out the important underground part of the plants like rhizome, bulb, corm etc. which may serve as an important diagnostic characteristic.
3. Pruning Shears:
The pruning shears (Fig. 4.1 B) is useful to collect the twig from tall trees.
4. Vasculum:
The vasculum (Fig. 4.1 C) is an elongated (45-60 cm.) container with oval ends generally made of aluminium or tin. It has a hinged tight lid. It is used to keep the collected plant material fresh for long time. The vasculum is coated with white paint to reflect light and also to locate easily due to its contrast with the green vegetation. A belt is fitted at both the ends, thereby one can carry it like a bag.
5. Magnifying lens:
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Sometimes a hand lens is required to observe some characteristics of the plant in the field.
6. Plant Press:
It is made up of two wireguage frames (Fig. 4.2A, B) of 30 cm. x 45 cm. Three (3) iron plates with two holes, one at each end are fitted at one side of the wire- gauge frame at equal distance. Similarly the other is also fitted with another three plates. Six thin ropes or chains (three on each side) should tighten at one end with the holes present on both sides of the plates.
After placing the plants in-between the blotting papers or newspapers, it should be kept between the wiregauge and then tightened properly after passing the rope through the holes of plates of opposite wiregauge frame.
7. Photographic Equipment:
It is necessary to take photographs mainly of the plants where preparation of Herbarium makes difficult.
Essay # 3. Techniques to Prepare Herbarium:
1. Selection and Collection of Plant Species:
The plant species selected for collection must have flowers and fruits (if present). The herbaceous plants should be collected with underground parts but for shrubs and trees a twig have to be collected. The size of the collected specimen should be about 25 cm.
There is no fixed rule for the number of specimens to be collected, but normally 4-6 sample plants are collected during routine collection. (Gymnosperms are collected along with cones and Pteridophytes along with cones or sori).
2. Records on Voucher Book:
The voucher book (Fig. 4.3) usually contains 100 pages each. The numbers are maintained serially i.e., from 1-100 and the second book should start with 101 and ends in 200.
The voucher book should be printed with the following things:
i. Name of the flora (where collection is conducted should be printed at the top)
ii. Field No.
iii. Date of collection
iv. Locality
v. Altitude
vi. Habit
vii. Any other information that can’t be preserved, and
viii. Name of collector.
3. Collection in Vasculum or in Polythene Bag:
After proper record the plants are collected in vasculum or in moist polythene bag, thereby the collected plants or plant parts would remain fresh.
4. Pressing of Specimens for Drying:
Before pressing, the plant material should be cleaned from mud or dust, if any. Plant or plant parts should spread nicely and kept between the blotting papers or old newspapers. Many such papers with collected plants are kept in-between the wire gauge and tightened properly with the rope as mentioned above (Fig. 4.4).
The papers will be wetted by soaking water from the plants. The press should be opened on following days and after keeping the plants in other dry papers, the press tightened as before. This process should continue for 15 days for the proper drying of plants. During rainy season or in humid weather the changing of paper should be done twice a day to obtain good result.
Plants which can hold more water are very difficult to dry. Sometimes growth of the plant may take place during drying inside the press. So these plants require to be killed before drying. The killing can be done by dipping the plants in boiling water containing a little amount of formaldehyde solution.
5. Poisoning:
The dried plants are then poisoned by dipping in saturated solution of mercuric chloride (HgCI2) in ethanol or in rectified spirit. After some time, the ethanol or rectified spirit evaporates and the specimens become dry.
6. Mounting:
The dry poisoned plants are then mounted on a comparatively hard sheet of paper — 42 cm x 29 cm (Fig. 4.5). The mounting is done by adhesive coated cellophane tape, gum or thread. The gum is applied with brush.
7. Labelling:
Label is a rectangular piece of paper of usually 12 cm x 10 cm size, pasted at the lower right of the Herbarium sheet.
The label should contain:
i. HERBARIUM SPECIMEN (Printed at the top),
ii. No.
iii. Date
iv. Name
v. Family or Natural order
vi. Locality
vii. Altitude
viii. Collected by ix. Identified by.
A model of the label is given below (Fig. 4.5).
Thus the Herbarium sheet may be defined as “a sheet of thick and tough paper having a measurement of 42 cm x 29 cm (international size), upon which perfectly dried and well displayed plant specimen is mounted and properly labelled (Fig. 4.5) for permanent retention at any Herbarium”.
After the preparation of Herbarium sheet, it should be covered with paper. The species are covered with a thin paper, called species cover, and all the species under a genus should be covered with comparatively thick paper called genus cover. The Herbarium sheets with their proper cover are kept in special cupboards or pigeon-holed cabinet (Fig. 4.6).
Though the specimens are poisoned before mounting, it is necessary to poison Herbarium sheets again at regular intervals (4-6 months) either by applying poison with brush or placing them inside a gas-chamber. This is to be done to keep off from damage of pests like insects (bookworms, silver fish etc.), fungi etc. In addition to that, naphthalene balls are also put in the pigeon holes to avoid damage from pests.
The International Botanical Congress recommended arranging the Herbarium sheets in a herbarium, following Engler and Prantl’s system of classification. But Bentham and Hooker’s system is followed by many Herbaria including Royal Botanic Garden, Kew, London; Central National Herbarium, Sibpur, Howrah, W. Bengal, India, and many others Indian Herbaria.
Essay # 4. Important Herbaria:
Lanjouw and Staffeu (1952, 1964) made an index of world Herbaria — about 850 Institutions including 50 most important Herbaria.
The name of some important Herbaria along with acronyms (given in bracket) and number of collections are given:
A. Important Herbaria of the World:
1. Museum of Natural History, Paris (P) established in 1635 ……….. 9,500,000
2. Royal Botanic Garden, Kew, England (K) established in 1841 ………………………… More than 7,000,000
3. New York Botanic Garden (NY), established in 1891 ………………. 7,000,000
4. Conservatoire at Jardin Botaniques de Geneve (G) founded in 1824 … 6,000,000
5. V. L. Komarov Botanical Institute, St. Petersburg (Leningrad), Russia (LE), established in 1823 …………. 5,770.000
6. Herbarium of Missouri Botanic Garden, St. Louis(MO), established in 1859… 5,400,000
7. British Museum of Natural History (BM) established in 1753 ………. 5,200,000
8. Harvard University, Cambridge, Mass. (GH), established in 1864 ……….. 5,005,000
9. Nuturhistorisches Museum, Win, Austria (W), established in 1807 ………… 5,000,000
10. Swedish Museum of Natural History, Stockholm (S), established in 1739 …………. 4,400,000
11. Smithsonian Institute, Washington D.C. (US), established in 1848 …………. 4,368,000
12. Central National Herbarium, Sibpur, Howrah, W. Bengal, India (CAL), established in 1793 …………… 2,500,000
B. Important Herbaria of India:
1. Central National Herbarium, Sibpur, Howrah, W. Bengal (CAL), established in 1793 …………… 2,500,000
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2. Herbarium of the Forest Research Institute, Dehradun (DD) ……….. 300,000
3. Madras Herbarium, Coimbatore (MH) ………. 150,000
4. Botanical Survey of India, Pune … 120,000
5. Regional Herbarium of the Botanical Survey of India, Shillong (ASSAM) ……….. 86,000
6. Herbarium of the National Botanical Research Institute, Lucknow (LWG) …………… 80,000
7. Industrial Section, Botanical Survey of India, Indian Museum, Kolkata …………. 40,000
8. Herbarium of the Botanical Survey of India, Allahabad (BSA) ……….. 26,440
Essay # 5. Functions of Herbarium:
The functions of the herbarium are:
1. To preserve properly the national plants including the type materials.
2. To maintain researches of both fundamental and applied aspects.
3. To fill the public requirement by giving scientific information in respect of plants, by organizing exhibition, training courses etc.
4. To give job and research facilities to the juniors.
5. To assist the loan and exchange of plants for different purposes for different purposes including research.
6. To help the students and scholars for collection (by seeing the date of collection and locality, from where the plant was collected) and easy identification of newly collected plant materials.
