Tuatara: Volume 3, Issue 2, August 1950
A Guide to the Collections of Botanical Specimens
A Guide to the Collections of Botanical Specimens
Part I.—Collection Methods as Illustrated by Flowering Plants
Collecting Gear: A sharp knife and a pair of pruning shears, field labels, notebook, black lead pencil, and a specimen container.
Field labels are required to attach to the specimen at the time of collecting, the most satisfactory are small tags of thin cardboard with a string for attachment.
When specimens are collected they may be transported back to the collector's base camp in a haversack or vasculum, but it is much more convenience to have a plant press out in the field and place the specimens in the press between sheets of paper as they are collected.
A simple press consists of two frames constructed of light wooden slats, held together by two leather straps which, when tightened, supply the pressure for pressing. The herbarium sheet on which the specimen is finally mounted measures 16½in. × 10½in. (Kew Standard) and thus the press is made to measure 17in. × 11in. The press frames can be made from 1½in. × ⅜in. slats using brass screws ⅝in. long for making the joints. Use five pieces lengthwise (17in.) and three pieces crosswise (11in.), one at each end and one across the centre. The two leather straps should measure about four feet long and at least one inch wide and have buckle holes starting at about two feet from the buckle itself.
Selection of the Specimen.—Always aim at collecting specimens which are most typical of the plant from which they are taken. A perfect specimen will show vegetative features, flower, and fruit. It is not always possible to get such a specimen so one has to be content with what is available at the time of collecting with a view in mind of collecting better specimens at a later date to complete the characters of the species. Collecting is performed for two purposes, firstly for a taxonomic study of the species, and secondly to show evidence that a species exists in the various localities that it has been collected from and thus the geographical range of the species can be determined and this in turn may give the Taxonomist some help in determining the origin and evolution of the species. Fertile material is much more useful as the Taxonomy of Angiosperms is based largely on reproductive characters. If the plants are small then the whole plant may be collected but if it is a large plant then only a portion can be taken as a specimen and care should be taken to select a typical specimen. It is often desirable to take a photograph of a large plant to substantiate the specimen. If a parasitic plant is collected then a good specimen page 68 of the host plant should also be collected, this also applies to epiphytic plants. It is often useful to collect a specimen of the bark in the case of forest trees as well as the specimen of the foliage and fruit. Plants which produce rhizomes or stolons should be selected to show these characters. An effort should be made to collect specimens of both sexes in the case of dioecious plants.
When taking a specimen from a plant remove it by a clean cut. Small plants may be removed from the substrate with a sharp knife and if a bulbous stock is present this should also be collected. Remember to always collect abundant material and it is a good plan to collect extra fruit and flowers if these are present.
Field Labelling and Cataloguing.—Written data must be supplied with each specimen to supply information that is not shown by the specimen itself, thus the making of proper and adequate field notes is just as important as the collecting of a good specimen. Field notes should be made at the time the actual specimen is collected. Specimens are numbered consecutively, as collected, in a simple sequence starting at one and continuing indefinitely. When a specimen is collected attach it to a label and on this write the specimen number and then make notes against the corresponding number in your field notebook. Field notes should include life form and habit, precise location, ecological data, diseases or parasites, and flower and fruiting characters which will be lost in future pressing and drying.
Numbers must not be duplicated in any form as this is likely to cause confusion at some later date. If ten specimens are taken from a single tree at the same time, then these ten are given the same number to show that each is an exact replica of the other. If on the other hand ten specimens are collected, of what appears to be the same species, from ten different trees then each of these must be assigned a different number. If the plants being collected are small, and the whole plant is taken as a specimen, then all those specimens taken from the same colony at the same gathering are assigned the same number, this applies to small herbs, etc., algae, small ferns, bryophytes, fungi, and lichens. In the case of bryophytes where a large number of plants are aggregated into a clump then a number is applied to the clump gathered and all subsequent specimens that may be broken off from this clump are assigned the same number as the original clump.
The proper numbering of your specimens is very important to Taxonomists who may subsequently examine your material, for example, AB has distributed twenty specimens of Metrosideros robusta (A. Cunn.) No. 2578; CD, who is preparing a monograph on this genus, receives one of these specimens and in the preparation of his monograph he studies this specimen and quotes it by its number (AB No. 2578) in his final monograph. EF receives a copy of CD's monograph and also has one of AB's specimens (No. 2578) and thus he knows page 69 definitely that the specimen he has is an exact replica of the specimen under consideration in the monograph.
A collection of plants which are not labelled or catalogued in some form are useless. When dioecious plants are collected, the two sexes are assigned different numbers as the specimens are from different plants. If photographs are taken in support of a specimen then these are given the number of the specimen to which they refer.
Pressing and Drying.—The aim is to prepare a flat dry specimen that can be mounted on a herbarium sheet.
Requirements: Plant press, newspaper specimen folders, ventilators, drying paper.
To make a specimen folder take a piece of newspaper measuring 17in. × 22in. and fold it once to make a folder 17in. × 11in. Place the specimen in this folder ready for pressing. As this is the approximate size of the sheet on which the specimen will eventually be mounted the folder gives a good guide for arranging the specimen. Ends of the specimen must not protrude from the folder, if the specimen is too long for the folder it must then be bent upon itself once or more to fit within the given space. This is often necessary when dealing with ferns, grasses, and sedges. The specimen remains in this folder until it is mounted. Write the specimen number on the bottom right hand corner of the folder to facilitate sorting of the folders.
Ventilators are made from double faced cardboard with corrugations in between (easily obtained from packing cartons) cut to measure 17in. × 11in. such that the corrugations run crosswise. Special corrugated aluminium ventilators are manufactured in U.S.A. but the standard size of American herbarium sheets is 16½in. × 11½in. and hence these ventilators are a little too wide and may also prove too expensive for the average collector.
Special drying paper resembling a thick type of blotting paper may be obtained, although two or three thicknesses of ordinary blotting paper serve very well. Failing this several thicknesses of newspaper can be used but is not so efficient. The drying papers should be trimmed to measure 17in. × 11in.
Place the specimens in the press in the following order: press frame, ventilator, drying paper (thoroughly dry), specimen folder (containing specimen), drying paper, ventilator, drying paper, specimen folder, etc. While stacking the press avoid bumps in the middle of the pile. This can be avoided by having thick portions of a specimen off centre and the successive bumps are arranged alternately opposite each other. It appears that most of the collectors in New Zealand merely place the specimen folders between wads of newspaper in the press, but drying under such conditions is slow and specimens are very apt to become mouldy. When all the specimens have been stacked in the press place the second press frame on the last ventilator page 70 and then do up the straps to supply a moderate pressure, tightening later when necessary. Place the filled press on its edge over a radiator or in some position where a current of warm air will pass up through the corrugations of the ventilator. A drying box can easily be made in which the press can be placed, thus: Make a box 17½in. wide and two feet deep, the length will be determined by the number of presses being used. A press should not be stacked more than two feet high and thus if only one press is used make the box two feet two inches long. Fix two rods of ⅜in. steel lengthwise in the box ten inches from the top and such that one is in six inches from each side. In a box taking one press fix one 60 watt electric light bulb in the centre of the bottom. This will supply a gentle heat for drying. Place the filled press edge down and lengthwise across the box in to rest on the rods. The gentle heat generated from the bulb passes up through the corrugations of the ventilator and hastens the drying process. Do not cover over the press while it is in the drying box as this will prevent the air current passing through the ventilators, but cover up any vacant space left in the box to prevent heat escaping.
Specimens press best when they are fresh but a wilted specimen may be revived by soaking in cold water for a while prior to pressing.
Many succulent plants, e.g., Peperomia, and plants with leathery leaves, e.g., Griselinia, loose their leaves during pressing. This may be overcome by immersing the specimen, prior to pressing, in boiling water for one minute to kill the outer cells of the leaf and thus allow water to escape and also to halt abscission layer formation.
A large fruit such as that found on Freycinetia may be slit down the centre, removing what would be the lower side of the specimen, leaving the upper side attached to the fruit stalk.
Go through the press every day and remove the specimen folders in which the specimens have dried, and change the drying papers. Place the used drying papers in a warm situation to dry thoroughly before using again. A well prepared specimen is dried out quickly but specimens can be ruined if too much heat is applied, and specimens if over-dried become very brittle. When all the specimens of a collection have been dried and taken from the press arrange them in numerical sequence and keep them in their folders until they can be mounted.
Mounting the Specimen.—Herbarium sheets are made of a light card and measures 16½in. × 10½in. Trimming of specimens should not be necessary at this stage as the specimen prior to pressing is trimmed to fit within a similar area. A space must be left clear in the right hand bottom corner of the sheet for the label. Arrangement of the specimen on the sheet with an artistic outlook adds much to the aesthetic value of the specimen. “Cellotape” is the best material available for attaching the specimen to the sheet. Place strips across the main stem at page 71 vantage points and across the side branches if necessary. It is a very bad policy to glue specimens to the sheet as vital parts to the taxonomist may be ruined. Glue is useful for attaching bryophyte clumps to a sheet. Long specimens that were bent upon themselves for pressing are mounted in a similar manner. If extra flowers and fruit have been collected these should be placed in an envelope which is then attached to the sheet, face side down, so that the envelope can be opened by lifting the flap. If the specimens are small mount as many as is convenient on the same sheet. Use the method outlined for mounting marine algae when dealing with delicate aquatic plants, but mount in freshwater.
Labelling the Herbarium Specimen.—When the specimen has been mounted and the species determined it may then be labelled. A label must contain: the name of the collector and his specimen number, name of the plant (when known), precise locality, and date of the collection. The value of the specimen is increased if additional data is incorporated in the basic label, e.g., habitat and altitude, form of the plant and notes on fruit and flower, and common names. This additional data is obtained from the field notebook. The systematic position of the plant and name of the person who identified the specimen may also be included. Every botanical name must have its authority quoted after it. Labels can be prepared with printed headings if the collector so desires, these look much neater than an ordinary printed label.
If desired the field tag may be removed from the specimen when it has been mounted and labelled.page 72
Preservation of the Specimen.—Cardboard boxes can be obtained of a standard size to store the mounted specimens in. The exact arrangement will depend on the number of specimens that the collector has. All the specimens of a species are placed in a folder of stiff paper, then all the species folders of that genus are placed within a folder labelled with the generic name and then all the generic folders of the family are placed in a box labelled with the family name. To prevent damage to the specimens by insects a repellant must be added to the boxes about every three months. Napthalene is satisfactory but p-dichloro-benzene seems to be the best available. A permanent method is to immerse the specimen before mounting in a solution of 2% mercuric chloride in 95% alcohol, or this may be painted on the specimen after it has been mounted. Mercuric chloride is a highly poisonous compound and this is a serious drawback against its use.
Identification of Specimens.—The species is determined by following out the various keys to families, genera, and species that are to be found in a Flora Manual. Having traced the species by means of the keys, check the specimen against the species description in the manual and then against a named specimen in a Museum Herbarium or in some other Institution. If you cannot trace a specimen out to its species or genus or if you are uncertain about your own identification then the specimen must be sent to a specialist for determination. When sending material to a specialist well labelled duplicates must be sent which will be kept by him. If you desire to send material to a specialist then you must contact him beforehand to find out whether he will be able to deal with your material.
Herbarium Packets.—Specimens of many Cryptogamic plants instead of being mounted or herbarium sheets may be kept in small packets. Packets are made from a medium weight quarto typing paper. To make a packet divide a sheet of the paper into thirds, bend the bottom third up and down flat, bend the top third over and down on to the bottom third, and bend back a flap 1½in. wide from each end and press the packet flat. Open the packet so prepared, place the specimen in the central region, fold it up again to enclose the specimen, and place the label on the front flap. There are many patterns and sizes that are used in making these packets but the author recommends the above outline as this type fits comfortably into a “shoe-box” in which they may be arranged alphabetically or numerically.
Part II.—Special Methods Used in the Various Plant Groups.
1. Algae—Algae are found in many different habitats, e.g., marine, freshwater, lakes streams and ponds, Epiphytes on forest trees, damp ground, stones, Plantonic, and on snow and ice.
It is desirable when dealing with small algae to keep preserved material as well as making pressed and dried herbarium specimens.page 73
Marine algae are preserved in 8% formalin in seawater plus a little borax to make the solution slightly alkaline. Freshwater algae are preserved in 5% formalin in freshwater plus borax. Add 5% glycreine to both these preserving fluids as a precaution against the fluid drying up. When preserved material is collected it is assigned the same number as the corresponding herbarium specimen.
(a) Marine Algae.—Marine algae may be collected from the intertidal region, beach drift after a storm, or by dredging in deeper water. When numbering specimens those of the same species gathered from the same colony at the same time are all given the same number. A small calico or canvas bag is most useful for collecting specimens in. Wrap the specimens as you collect them in pieces of newspaper and write the number with a grease pencil on the outside of the package. Wrap all specimens of one number together but don't mix any others in with these. Small glass collecting tubes are very handy for small algae, but remember to put only those specimens of the same number in one tube and write the number on the stopper. Make notes on the level of the plant in the community, its abundance, whether in an exposed or sheltered locality, and on the type of substrate. Herbarium sheets for algae are generally of a lighter material than those used for vascular plants. A light weight drawing paper is very satisfactory and is used in various sizes depending on the specimens being mounted but never larger than the standard herbarium sheet. For the larger and coarser species use the ordinary herbarium sheets. Specimens may be mounted straight after collecting or they may be dried and stored until it is convenient to mount them. A dried specimen is soaked in water prior to mounting until it resumes its natural form. If, after collecting your specimens, you dry them, then tie a tag to the specimen on which the specimen number is written.
Select the specimen and the sheet on which you wish to mount it. Write in the bottom right hand corner the specimen number, using a dark non-indelible pencil or waterproof ink. Place the specimen in a basin of seawater and float it out into its natural condition, slip the mounting sheet into the water and underneath the specimen and then slip one hand underneath the sheet. Slowly bring the sheet with the specimen on it up to the surface of the water, tapping it slightly from beneath and making any adjustments to arrangement with the free hand, using a mounting needle. Remove the specimen sheet completely from the water, tilt it a little to allow free water to drain off the sheet, and then lay the sheet, specimen side uppermost, on a towel and with a free edge of the towel mop up as much water as possible without disturbing the specimen. Place the specimens in a press as done with Flowering Plants except that the specimen folders are omitted, but spread a piece of muslin over the specimen side of the sheet to prevent page 74 it sticking to the drying paper. Change the drying papers after about one hour and then twice daily until the specimens are dry. Most specimens will stick to the sheet but in the case of the coarser species which don't stick, use cellotape to attach them. It is not necessary to float out many of the larger and coarser red and brown algae. Wash these free of sand and lay them out to partially dry but they must be mounted while still flaccid. To mount, lay the specimen on the sheet and arrange it in a natural manner and press as usual. When collecting encrusting algae such as Lithothamnium break off a piece of the rock with the alga on it, dry, and attach a label to the rock. Softer encrusting types such as Petrospongium may be scraped from the substrate with a sharp knife and placed on a mounting sheet and pressed as usual. Some collectors use freshwater when mounting marine algae but this practice is to be discouraged as this will cause cell rupture in many of the more delicate reds. Some reds disintegrate very rapidly and need to be mounted soon after collecting.
(b) Freshwater Algae.—The majority of freshwater algae are either filamentous or microscopic. Members of the Charales do reach an appreciable size and complexity and these are mounted as for marine algae but are floated out in freshwater. Always preserve a sample. Herbarium specimens may be prepared in several ways. Filamentous types may be floated out on to a sheet and pressed, or a lump may be spread out on newspaper and allowed to dry gently and the dried specimen is then placed in a herbarium packet. Gelatinous types are spread out on a piece of colourless cellophane and dried, the specimen then being placed in a packet. Cellophane is used because a specimen can be soaked up rapidly when required and under such conditions is more stable than paper.
Reference miscroscopic slides of freshwater algae and small marine algae are prepared using glycerine jelly, that has been coloured a pale red with eosin, as a mounting medium.
Treat terrestial algae as above.
(c) Planktonic Algae.—Plankton is composed of small organisms, both algal and animal, which float in the surface layers of the larger water bodies, both freshwater and marine. A conical shaped net made of bolting silk with a collecting jar attached to the apex is used to collect plankton samples. The net is towed through the water and the plankton is filtered from the water passing through the net and collects in the jar at the apex. The organisms will be suspended in the water remaining in the collecting jar; add to this formalin to make a 5% solution and leave to stand. After the plankton has settled on the bottom of the jar decant off most of the surplus clear solution and transfer material to a specimen tube and label. For general reference prepare slides with eosin-glycerine jelly, but if Diatoms are being dealt with a special medium is required with a high refractive index, e.g., “Euparal” so as to render the wall structures clearly visible.page 75
It is seldom that a pure sample of any one organism will be collected, most samples being mixtures in which the proportions of the various components will vary with the season and locality of collecting. Many Planktonic organisms have a fairly regular seasonal cycle of occurrence.
2. Fungi.—Many fungi, particularly smaller types, are parasitic and these are preserved along with a portion of the infected host. In the case of many parasitic forms it is necessary to retain living material in order to establish a culture. For general purposes use 10% formalin as a preservative. Most of the macroscopic fungi are saprophytic and it is the fruiting body that forms the macroscopic portion. These may be fleshy, leathery, or woody. Thoroughly dry woody and leathery types and store in herbarium packets or in cardboard boxes of suitable size to take the specimen. Fleshy fungi disintegrate very rapidly and must be dealt with soon after collecting. To make a herbarium specimen dry gently, don't cook it. Drying causes the specimen to shrivel up greatly and thus it is essential that scaled coloured drawings be made of the specimen before it is dried. Several sketches should be made including several aspects to show structure, and a median longitudinal view to show the disposition of the hymenium. Disintegration of fleshy types takes place even in preservative. The addition of 8% sucrose to the preservative will temporarily preserve the colour. Fleshy fungi can be preserved more or less in their natural form by impregnating the specimen with a synthetic resin. Soak the specimen in a mixture of 5 parts formalin and 3 parts of liquid carbolic acid until it has soaked well into the tissues of the specimen. Dry the surface carefully with a cloth and suspend the specimen over .880 ammonia. A resin forms in the tissues of the specimen making it solid and giving it the appearance of a “Candy” specimen. Specimens so prepared will keep indefinitely, but must be stored in a dry place.
3. Bryophytes.—Epipytic bryophytes and those growing on a solid substrate can generally be peeled off in a clump but the smaller acrocarpous terrestial species require to be removed along with a thin layer of the substrate to hold it together. Having removed the specimen place it in the middle of a quarter sheet of newspaper and fold this as for making a herbarium packet and press firmly between the hands. Write the specimen's number on the packet so prepared and make field notes. Spread these packets out in a warm situation to dry. Specimens may be mounted on herebarium sheets if desired by gluing a clump on to a sheet or attaching larger individual plants by means of cellotape. It is much more convenient to keep the specimens in herbarium packets placing the label on the front flap. When material is required for examination soak a little in water and it will assume its natural form. When collecting the larger species, e.g., Dawsonia, all those collected from the same colony are given the same number and several of these page 76 specimens are mounted on an ordinary herbarium sheet. Prepare microscope slides of leaves and portions of the plant for reference when “attempting” to identify material. Glycerine jelly is used as the mounting medium, and in the case of leaf preparations add .2% cupric acetate to the glycerine jelly. Make preserved specimens of thallose liverworts and fertile foliose liverworts as well as dried herbarium material. Use 5% formalin with .4% cupric acetate which preserves the green colour of the specimen. Remember to always gather abundant material and aim at collecting fertile specimens.
4. Lichens.—In general lichens are treated the same as bryophytes. In the case of many of the larger foliose lichens it is advantageous to press the specimens and mount on herbarium sheets. Thin crustose epipyhtic forms are removed along with a thin slice of the bark while similar epilythic forms are collected with a portion of the rock substrate.
5. Ferns and other Vascular Cryptogams.—Treat as for flowering plants but always aim at getting fertile material. In the fern allies sporangia are either borne in special strobili, e.g., Lycopodium, or in the axils of the ordinary leaves, e.g., Isoetes. In the ferns the sporangia are borne either on the margin or underside of vegetative leaves or on special leaves. A good herbarium specimen will show both fertile and sterile fronds attached to a portion of the rhizome. Filmy ferns wither very quickly and these are revived prior to pressing by soaking in water. If the specimens taken a large species, e.g., Cyathea, are only pinnae from a large frond then the size of the frond and the position on the frond that the specimens were taken from should be noted.
6. Gymnosperms.—Treat as for flowering plants. Endeavour to obtain both male and female fructifications. The only indigenous species with a large cone is Agathis australis. The large female cone of the Kauri disintegrates when mature or when dried out. To overcome this give the cone a coating of varnish soon after collecting, which will prevent disintegration of the cone providing it is handled gently. Most of the introduced species have large female cones, e.g., Pinus, and these may be prevented from opening on drying by varninshing also. Specimens with large woody cones should not be placed in the press with other specimens unless they are packed up till level, but it is much easier to press them separately.
Literature on New Zealand Plants.
There have been several volumes on the New Zealand Flora published, but only one of these deals with the flora as a whole. Only the more general works that are readily available to the average collector are here mentioned. Many revisions of families, genera and species, and papers dealing with numerous aspects of our flora have appeared in the Transactions of the Royal Society of New Zealand. page 77 Any collector who is commencing a study of some special group of plants should consult the author-index of this journal for references. By making use of the bibliography at the end of most articles, one reference leads to another.
Hooker, J. D., 1867—Handbook of New Zealand Flora. Vol. 2. London. Includes all the known plants of that time.
Martin, W.—The New Zealand Flora. Whitcombe & Tombs, N.Z. A general account of the flora.
Cheeseman, T. F., 1925—Manual of New Zealand Flora. Govt. Printer. Includes Vascular Cryptogams and Spermaphyta.
Chapman, V. J.—A Revision of Marine Chlorophyceae and Cyanophyceae of New Zealand. (In preparation.)
Laing, R. M., 1927-29.—A Reference List of New Zealand Algae. T.R.S.N.Z. Vols. 57 & 60.
Lindauer, V. W., 1947—An Annotated List of the Brown Seaweeds, Phaeophyceae of New Zealand. T.R.S.N.Z. Vol. 76. A Revision of the Phaeophyceae of New Zealand. (In preperation.)
Cone, G. B., 1948—Some Notes on Agarics. Bull. Well. Bot. Soc. No. 20.
Cunningham, G. H., 1925—Fungus Diseases of Frut Trees. Brett, Printers and Publishers, Auckland.
1931 Rust Fungi of New Zealand. John McIndoe, Dunedin.
1944 The Gasteromycetes of Australia and New Zealand. John McIndoe, Dunedin.
New Zealand Polyporaceae. Plant Diseases Bulletins No.s 72, 73, 74, 75, 76, 81.
Allan, H. H., 1948—A Note on Lichens with a Key to the Commoner New Zealand Genera. Tuatara, Vol. 1, No. 3.
1949 A Note on the Crustaceous Lichens of New Zealand. Ibid. Vol. II, No. 1.
1949 A Key to the Stictaceae of New Zealand. Ibid. Vol. II, No. 2.
Allison, K. W., 1949. Some Notes on Mosses with Key to Commoner New Zealand Genera. Tuatara, Vol. II, No. 3.
Dixon, H. N., 1913-1927. Studies in the Bryology of New Zealand. Bulletin of New Zealand Inst. No. 3, Parts 1-6.
Hodgson, E. Amy., 1941-49. New Zealand Hepaticae. Parts 1-6. T.R.S.N.Z. Vols. 71, 73, 74, 76 77.
1950 The Classification of New Zealand Hepticae. Tuatara. Vol. II, No. 1.
Crookes, M. W.—New Zealand Ferns (In print). Whitcombe & Tombs.
Allan, H. H., 1928.—Trees and Shrubs and how to Identify Them. Whitcombe & Tombs, N.Z. An Introduction to the Grasses of New Zealand. D.S.I.R. Bulletin No. 48. Govt. Printer, Wellington
1940 A Handbook of the Naturalised Flora of New Zealand. D.S.I.R. Bulletin No. 83. Govt. Printer.
Cockayne, L and Phillips-Turner, E.—The Trees of New Zealand. Govt. Printer, Wellington.
Laing, R. M. and Blackwell, E. W.—Plants of New Zealand. 4th Edition. Whitcombe & Tombs.