Collection and Preservation of Plants

In this article we will discuss about the Collection and Preservation of Various Plants:- 1. Collection and Preservation of Algae 2. Collection and Preservation of Fungi 3. Collection and Preservation of Lichens 4. Collection & Preservation of Bryophytes 5. Collection and Preservation of Ferns and Other Pteridophytes 6. Collection and Preservation of Gymnosperm 7. Collection and Preservation of Angiosperms.

Contents:

1. Collection and Preservation of Algae
2. Collection and Preservation of Fungi
3. Collection and Preservation of Lichens
4. Collection & Preservation of Bryophytes
5. Collection and Preservation of Ferns and Other Pteridophytes
6. Collection and Preservation of Gymnosperm
7. Collection and Preservation of Angiosperms

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1. Collection and Preservation of Algae:

Most of the filamentous and other macrophytic algae are collected from the natural habitats by collecting net or directly by hand using scalpel. Planktonic algae are collected through filtration of surface water using plankton net (mesh sizes 40 – 60 µm). Soil algae, however, are isolated through culture in selective algal culture media.

After collection of different algae using various methods, they are cleaned, if required, and finally preserved in glass or plastic container using preservatives like 4% formalin or formal-acetic-alcohol. All species are labelled properly for their identity.

Algae samples can also be preserved in culture media or in dry or lyophilized state. Marine macroscopic sea weeds or charophytes are dried after collection and preserved as herbarium sheets.

2. Collection and Preservation of Fungi:

Aquatic saprophytic fungi are collected along with substratum and then preserved in 4% formalin or FAA solution. Most of ascomycetous and basidiomycetous fungi have conspicuous fruit bodies. Fruit bodies are collected carefully and then preserved either in FAA solution or 5% formalin solution or even as over-dry specimens.

There are many fungi which are parasitic. These are collected from 4hc infected host plant and preserved cither in 5% formalin solution or as dry herbarium sheets. Except a few obligate parasitic forms, most of the fungi can be artificially cultured in selective culture media and then preserved in cold for a considerable period of time.

3. Collection and Preservation of Lichens:

Lichess are collected from tree barks or from rocky substratum using scalpel, either along with bark or lichen thalli alone and then dried. Finally, the specimens are preserved as herbarium sheets or dry specimens in polythene packets with proper labelling. Sometimes thalli can be preserved in 5% formalin solution.

4. Collection & Preservation of Bryophytes:

Bryophytes are collected from their natural habitats using scalpel and forceps. They are thoroughly washed in water and cleaned properly. Finally they are preserved in 10% formalin solution. Sometimes bryophytic thallus, after cleaning, are dried at 50°C and then stored for future study. Jungermanniales and most of the mosses are kept in this manner.

There are some special techniques for moss preservation:

Mosses can be preserved as museum specimen in the following way:

(a) Fresh specimens are wiped of all water and then kept in a glass trough filled with a pre-treating solution (Sodium sulphite – 16 gms., Conc. H₂SO₄ – 20 ml. and Distilled water – 1,000 ml.) overnight in air tight condition.

(b) Then the specimens are washed in distilled water and treated in saturated solution of CuSO₄ for 24 hours.

(c) Finally, the specimens are washed in distilled water and tied on glass plates and preserved in glass bottles using formalin solution (4%).

5. Collection and Preservation of Ferns and Other Pteridophytes:

Usually the whole plant along with rhizomes and strobili or sori is selected for collection. With the help of scalpel and forceps, fresh specimens are collected from their natural habitat and then mostly dried for preparation of herbarium sheets.

In some cases, of course, for histological studies, the fresh specimens are preserved in 10% formalin after proper cleaning, soon after collection from their natural habitats. In ease of ferns, rhizome, fertile and sterile fronds a whole or a part must be collected and preserved for future studies.

6. Collection and Preservation of Gymnosperm:

Usually twigs of about 15-25 cm. size with sex organs should be collected from their natural habitats. The specimens are then pressed and dried for herbarium preparation. Sometimes young twigs or cones are preserved in 10% formalin for anatomical studies. Dry coniferous cones, sporophylls of cycads and Ginkgo can also be collected from their natural habitats and preserved as dry specimens.

7. Collection and Preservation of Angiosperms:

Fresh plant materials are handled in three ways for processing into herbarium specimens. When time and carrying facilities permit, the most satisfactory method is to press each plant as it is collected. This is done in a field press made up of a pair of collecting frames, a few blotting papers, and folded sheets of newsprints.

A second method is to accumulate the material in a metal collecting can or vasculum: For actual use, the vasculum is first lined with a few layers of well moistened newsprint to prevent wilting of specimens, and experience has shown that plants keep better in a full vasculum.

Then the plants should be pressed when opportunity permits. The third method is to carry collected specimens in a rucksack. They are then pressed as soon as possible after return to camp headquarters.

A few equipment are indispensable for plant collection, namely a collecting pick, a strong knife or a machete, and a pair of pruning shears etc. Usually, during collection of plant materials, either whole rooted plants (in case of small herbs) or twigs of 15 – 20 cm. in length are plucked by knife and then used for preparation of dry specimens in plant press.

There are different kinds of plant presses, the selection of which depends on the use to be made of them and on the drying techniques to be used. The efficiency of the press is determined largely by its ability to hold the material under a constant and firm pressure to dry the specimen to a degree short of crispness, and to retain the colours of all parts as far as possible.

Usually, most presses comprise a pair of wood or- metal frames, blotters, pressing papers and straps or strong cords.

The specimen to be pressed is arranged within the folded sheets of pressing paper that has been placed on a blotter, and another placed over it. If the plants are to be dried with the aid of artificial heat, a sheet of corrugated material is used between each pressing paper and its specimen.

Otherwise, no corrugates are used and the press is built up by an alternation of blotter-pressing paper-blotter etc. The press frames are on top and bottom of the press, and it is then locked up by means of straps or stout cords.

A minimum of about a week is required for completion of drying. Blotters must be changed 3 or 4 times within this period. Every wet blotter must be dried, usually by placing in the sun. Mounting specimens is a phase of specimen preparation that has been developed from a number of different approaches.

Usually, specimens are mounted on sheets of standard size herbarium paper (30 – 40 cm). After mounting, they are stored in special cases built to accommodate sheets of this size. Most herbaria use a glue or paste to fasten specimens to the sheets.

There are 3 techniques most commonly used in mounting specimens with paste or glue – Glass plate method, pressing paper method or by the use of special adhesive. Sometimes delicate specimens can also be preserved in 5 – 10% formalin solution in a glass jar.

All the harbarium sheets/preserved specimens should be properly identified and labelled. The label should contain the name and family of the plant and also the date of collection, locality of collection and any other habitat feature of importance.

Herbarium specimens are subject to serious damage by being eaten by various insects. Thus different insecticides, like Para dichlorobenzene (PDB), Carbon tetra-chloride or DDT etc., can be used to prevent this. Fumigation is made within the storing home or cabinets from time to time.

For retention of green colouration of collected plant specimens, the plants, after collection, should be placed directly in a special solution for a few days and then dried for herbarium preparation. The composition of one such solution as suggested by Keefe (1926) is as follows: 90 ml. 50% ethyl alcohol, 5 ml. formalin, 2.5 ml. glycerine, 20 gms. Cupric chloride, 2.5 gm. uranium nitrate.