Guide to Plant Collection & Identification by Jane M. Bowles, Department of Plant Sciences, UWO

Table of Contents Plant Names Collecting Identification References Appendix I Appendix II

2. PLANT COLLECTING

  1. The purposes of collecting
  2. What to look for in a specimen
  3. What to collect
  4. How to collect
  5. Notes to take
  6. Pressing and drying vascular plants
  7. The plant press
  8. Laying out the specimens for pressing
  9. Mounting specimens
  10. The label
  11. Mosses & lichens
  12. Herbarium packets

2.1 The purposes of collecting

Today there are two main reasons for collecting plants. The first is to obtain records and specimens of plants, either for a personal collection or to be stored in an herbarium. Properly run herbaria where specimens are suitably stored and catalogued have great scientific value. They are almost always pleased to accept good, correctly labeled specimens and are generally willing to allow serious workers access to their collections. The merits of personal collections are less obvious. Small collections of common plants may have value as reference for identification, but gathering of plants for personal collections is generally unnecessary and should be discouraged. In England, over-enthusiastic collection by amateurs, together with loss of habitat has caused the extinction or near-extinction of a number of plants, especially orchids. It is now illegal to pick or collect any plant in Britain without the consent of the landowner.

The second major reason for plant collecting is to identify an unknown specimen encountered during fieldwork at a later time. Often these specimens consist of small, atypical plants with no flowering or fruiting parts. As herbarium specimens they are often next to useless. Nevertheless, any vegetation survey should include, where possible, collection of at least one specimen of each species encountered. This is known as the voucher collection and should either be kept by the worker for future reference if needed, or stored in a local herbarium.

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2.2 What to look for in a specimen

Specimens for collection should be as complete as possible. Ideally flowers and fruit should be included, as well as vegetative parts. Clearly, in most cases, this is impossible since ripe fruit and flowers do not usually occur at the same time. Often, however, remains of growth from the previous year can be found at the base of the plant or on another specimen nearby. Only collect fruits or seeds if you are certain that they belong to the same plant or the same species.

Specimens should be typical and healthy, with at least some fully expanded leaves where possible. Avoid taking diminutive individuals because they fit into a press more easily or are easier to reach. Take the plant from its typical habitat. If a species normally grows in woodland, do not collect specimens growing by the roadside or in a clearing. Sometimes leaf shape, flower colour and other characters are completely altered on plants growing in full sunlight.

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2.3 What to collect

The whole of small vascular plants should be collected including the underground portion. Roots, trailing or underground stems and storage organs are often helpful (and sometimes essential) in identifying specimens. A strong knife or small trowel is helpful for digging out a plant. Excess soil can be shaken off, or washed off carefully if water is available.

Mosses and lichens should also be taken whole. Where they grow in mats a good handful should be removed. Ideally the specimen should be pure, not mixed with other species. Sometimes it is necessary to pick out individual plants one by one. In this case at least half a dozen to a dozen specimens should be taken. Mosses and lichens growing in cushions or clumps, or closely growing on the substrate should be cut away with some of the substrate. Thus the specimen consists of bark, rotting wood, soil, humus and so on as well as the plant. This ensures that the growth form of the plant is retained. Soil can be removed much more easily once the specimen has dried. Again "clean" specimens containing only one species should be aimed at. If fruiting bodies are available, these too should be collected, or identification may be impossible.

When taking the whole plant is out of the question, specimens containing all essential features (all leaf types, twigs, flowers, fruits and so on) must be cut from the plant. If the species is a large herb such as a thistle, the specimen should include basal leaves as well as enough stem to show the range of stem leaves and flowering and fruiting material. Shrub specimens should include leaves, old and new twigs, buds where possible, and fruit and/or flowers. Always include leaves from the main branch, as leaves on side shoots may be atypical (however, in the difficult hawthorn genus Crataegus, the opposite is likely to be the case: lateral, short shoots will often have more typical leaves than the main, long shoot - TAD). If lower and upper leaves are different, or there is significant variation between a shaded and unshaded side of a tree, then collections should be made from both. To minimize damage to parent trees and to specimens, twigs should always be cut off cleanly with a sharp knife or pruners. Breaking the twig can strip the bark and ruin a specimen or cause unnecessary harm to the tree or shrub from which it was taken.

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2.4 How to collect

Ideally, collections of vascular plants should be put immediately into a field press, because this produces the best looking specimens. A traditional field press is described by Savile (1979), a simpler version is shown in Figure 1. Field presses are rather bulky to carry around and may prove impractical in some cases. I use a collecting scroll made of a rolled-up strip of plastic table covering. Starting at one end, the plants are rolled into the scroll one by one. The collecting scroll is illustrated in Figure 2.

Collecting into plastic bags is another option favoured by many field botanists. A range of bag sizes should be available. Small plants can be placed singly, or two or three together if necessary, in a suitably sized bag. Plastic bags are not recommended for serious collecting because the risk of damaging the specimen is very great. Petals are likely to be knocked off, and stems will almost certainly be bent or broken. Collecting into a field press or a traditional vasculum, a sort of metal satchel, prevents this. The bag should then be blown up by mouth and knotted to seal it. Blowing up the bag adds a small amount of moisture and helps to cushion the contents. Full bags can be carried in a larger bag or rucksack. Care should be taken to keep collections as cool as possible and prevent them from being crushed

With each plant, and firmly attached to it if several plants are collected together, should be a label bearing a collection number which corresponds to numbered notes in the collecting book. Jewelers' tags are an excellent means of labeling plants because they are easy to tie on and, being cardboard, can be dried, erased and used again 5 or 6 times before they are finished.

Mosses and lichens should always be collected in paper bags or envelopes. These have the advantage of allowing the plant to be dried in the same bag. Notes can be written directly on the bag.

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2.5 Notes to take

Every specimen should be accompanied by comprehensive notes retained in a collecting note book. These notes may not only aid in identification of the material, but will later be used to complete the information on the herbarium label. It is far better to take too many notes than too few, and is dangerous to trust information to memory, especially as there may often be several months or more between collection and processing. The notes should contain the following information:

(i) Collection number: A serial number specific to collector and specimen. The number may start at 1 and continue through the collector's life time. Other people augment the serial number with notes of name, place, date and so on. For example, JS/ONT/82/237 may be specimen #237 collected by John Smith in Ontario in 1982.

(ii) The name of the plant: This is important as it helps the collector remember the individual specimen even if the labels are accidently lost or mixed. Even if the collector has no idea what the specimen is, it is sometimes useful to give a completely arbitrary name such as "Lacy Moss" or "Big Leaf". This has a double advantage in vegetation surveys in that this name can then be applied to other specimens of the same species if they are encountered before the material has been identified. This way there is no need to collect the plant more than once or try to remember if it is "Unknown #34" or "Unknown #35"

(iii) Locality: This should be as detailed as possible, including the name of roads lakes and so on in the vicinity, as well as Township or District. The latitude and longitude or the UTM Grid Reference and Map Number will be needed for the herbarium label, but can be added later if they are not known.

(iv) Description: This should include everything about the plant that is not obvious on the herbarium specimen. Essential items are the height, type of bark, whether the stem is upright, sprawling or drooping, obvious smells, whether the plant is clumped, single or growing in patches, and the presence of creeping or underground stems. Flower and fruit colour should also be noted as these often fade on dried specimens.

(v) Habitat: This should include the general habitat as well as more specific details of micro-habitat. Important points are type of soil or other substrate (sand, clay, granite, dead wood, other vegetation), associated species, moisture and aspect (fully exposed on a south facing bank; in a damp hollow under dense scrub, etc). The more careful and detailed such notes are the more useful they become.

(vi) Date.

(vii) Names of collector(s).

(viii) Notes: Space should be left to note the name of the person who makes the final determination (identification), the date on which it is made and the place were the specimen is sent or stored. The receiving herbarium will add their own accession number to the specimen.

Many herbaria and professional collectors have form-style collecting books with printed serial numbers. Carbon copies of field notes are made on perforated pages. These pages are torn out and placed with specimens when they are pressed. The original is retained in the notebook and kept for records. Even without a printed notebook, collecting and note taking can be done very efficiently if a constant format is used.

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2.6 Pressing and drying vascular plants

The most important thing to do with freshly collected material is to dry it out as fast as possible. This prevents fungal infections and preserves colour.

Vascular plants must be pressed and dried as soon as possible after they are collected. Usually this means that plants should be pressed the day they are collected. It is an important aspect of plant collecting that enough time be left at the end of the day to process the specimens. If this includes identification, this stage may be quite slow . When plants have to be left overnight they should be put in a cool place. Sometimes woody specimens can be placed in water for a day or so to force buds or restore wilting leaves. Pressing vascular plant specimens
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2.7 The plant press

Pressing vascular plant specimens The plant press is designed so that plants can be dried quickly while being pressed flat. It consists of two cross-slatted wooded frames about the size of a folded newspaper ( 46-31 cm). Plant specimens are laid in folded newspaper between layers of blotter sheets or foam and corrugated cardboard. The newspaper provides a folder for the plant. The paper, blotter and foam draw the moisture away from the specimen. Blotters can be thick blotting paper or felt, or thin sheets of the polyurethane foam that is laid down under carpets. Foam is best for woody species or plants with large fruits, because the foam adjusts to the contours of the thickest parts of the specimen while at the same time ensuring that the leaves are well-pressed. The cardboard allows air circulation within the press to speeds up the drying process, and helps keep the specimens flat. Plants in their newspaper folders are piled in layers of alternating blotter and cardboard on one of the wooden frames (i.e., cardboard - blotter - folded newspaper [with plant inside] - blotter - cardboard - blotter - etc.). When laying out of the specimens is complete, the second frame is laid on top of the pile which is compressed and strapped as tightly as possible. The press is then placed to dry in warm (not hot), dry, circulating air. After 24 hours the paper and blotters should be changed to enhance the drying process. After this, the specimens may be left undisturbed for several months or weeks until they are completely dry and the press can be emptied. The straps have to be tightened periodically as the plant material shrinks.


Herbaria have special drying cabinets in which the presses are dried. In the field drying is not so easy, but it should have priority as specimens are easily ruined if they remain damp. A press left upright on a rock, or kept on a car roof rack, where air can circulate will dry much faster than one left lying in a tent, vehicle or room. Heaters in motel rooms on low heat can also be pressed into effective service. However drying specimens too fast can result in scorching and shriveling. For fuller information on drying and maintaining presses see Savile (1979).

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2.8 Laying out the specimens for pressing

Two important points should be borne in mind when plants are prepared for the press: (i) that the dried specimen should fit neatly onto a standard herbarium sheet of 420 x 297 mm; and (ii) that as many features as possible should be visible on the mounted specimen. Here are a number of tips which, if followed, will help produce attractive and worthwhile mounted material. With experience, all collectors develop their own techniques.

If a specimen is too tall to fit in the press or on the herbarium sheet, make a zig-zag bend in the stem. This shortens the effective length of the specimen without any of the material being lost. Plants with many long, narrow leaves such as grasses will bend and press more neatly if a piece of paper with a slit in it is placed over the elbow of the bend to hold all the leaves together.

Too many leaves on a herbarium sheet look untidy and can obscure detail. Where it can be done without destroying information, snip off some of the leaves, but ALWAYS leave part of the petiole so that it is evident that leaves have been removed.

Branches that are not naturally flat can be made easier to press if the angles or twigs are bent in the appropriate direction before the plant is laid on the newspaper. Care should be taken not to actually sever twigs or leaves.

The specimen should be laid out so that there is minimum of overlap between parts. Sometimes this involves spreading the plant unnaturally. Start near the folded edge of the newspaper and hold the parts in the desired position. Fold over enough newspaper to cover these parts and hold it down with the flat of the hand. Then move to the next portion of the plant, arrange it and fold down a few more centimeters of newspaper. Continue until all the newspaper is folded down and the flats of two hands can cover the whole sheet. You will find that you sometimes need all three hands as well as your chin for this process, but it will be worth it when you finally see the specimen mounted.

When stems are very thick they can be sliced lengthwise so that they are less bulky. Leaves of plants with thick stems do not always get sufficiently pressed and may tend to wrinkle. Using foam sheets helps prevent this because the foam molds itself around the specimen and ensures an even pressure throughout. The end of woody stems should be sliced diagonally so that the colour of the wood and pith are displayed.

Leaves or petals which have wilted, or are folded over, will not always lie flat for pressing. A piece of wet newspaper will "stick" them in place. By the time the newspaper is dry the leaf will have stabilized and cause no more trouble. On every mount, the back of at least one leaf should always be visible. Sometimes this involves twisting a petiole to obtain the desired effect.

If there are several flowers on a specimen, some should always be pressed open and flat so that the inside is displayed. This can usually be achieved by careful, deliberate pressure with the thumb before the newspaper is folded shut.

Loose seeds and fruit can be placed in a small paper packet and pressed with the specimen. Later this packet will be glued to the herbarium sheet. Some conifers loose most of their needles on dried specimens. Once the material is dried, the needles can be shaken off and placed in a packet.

Once plants are pressed, changing the paper after the first 24 hours not only enhances drying, but allows the collector to make cosmetic adjustments to the specimen while it is still supple. Folded leaves are the main problem. These can be prised open with a mounted needle and pressed flat the second time round. Sometimes petals stick to the newspaper as they dry and are impossible to remove without damage once they have become brittle. Changing the newspaper before the flower has dried completely helps to prevent this.

Pressing plants can be a long and laborious process. It will take considerably less time if you avoid reading all the advertisements and news items in the old newspapers. Sometimes, however, these can help considerably in elevating boredom!

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2.9 Mounting specimens

Once material is pressed and thoroughly dried, it is mounted on herbarium sheets. The standard size for these sheets is 420 x 297 mm. They should be made from stiff, acid-free, paper or cardboard of good quality so that they will not turn yellow or crack with age.

Specimens should be laid on the sheet in an attractive, space-filling way. Space should be left in the lower right hand corner for the herbarium label. The sheet should be as full as possible without being crowded. When the arrangement is satisfactory, the specimen may be stuck to the sheet. Traditional methods require pasting the plant onto the sheet and reinforcing it with strips of tape or plastic stripping. The disadvantages are that pasting does not allow easy removal of parts for examination; tape is unsightly and may obscure important details; the ingredients for plastic stripping are highly carcinogenic, and in the presence of moth balls the plastic may become tacky.

One easy, cheap, efficient and attractive method of mounting plants is to use Elmers Glue-all. This make of white glue contains no ingredients which are likely to harm or alter the specimen, it is strong, comes in convenient containers and dries transparent. It can be dabbed along stems, through roots, under leaves and below flowers and it dries in less than an hour. Specimens should be glued so that there are no loose parts and then dried flat with weights where necessary. Note that many herbaria have their own preferred method of mounting specimens. Gluing a specimen prior to mounting
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2.10 The label

Most herbaria have printed labels about 8 x 10 cm which are filled in and glued to each herbarium sheet. Elements of a typical label are shown below (click HERE for an image of an actual specimen label from the ROM Vascular Plant Herbarium):

SOMEWHERE HERBARIUM

PLANTS OF . . . . . . . . . . . . . . . . . . . .

Name:

Family:

Locality:              Lat:     Long:    

Habitat:

Notes:

Collector: #:             Date:

Det. by:              Date:

Acc.#:



This provides room for all the essential information noted by the collector at the time of gathering, plus a catalogue number for the plant in the herbarium register (Acc.#). Most herbaria now keep specimen records in a database and have programs which create labels automatically. Before collecting and donating specimens to a herbarium, you should find out the field names, sizes and codes for the database they use so that you can provide information in a consistent format.

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2.11 Mosses & Lichens

If mosses and lichens have been collected in paper bags or packets, they can be spread out to air dry either on or in the packets. Some of the larger species should be pressed lightly in a newspaper folder so that they are not so bulky when packaged, but mosses and lichens should never be placed in a press for vascular plants. Although mosses are not particularly susceptible to mold if they are allowed to remain damp, they may continue to grow in the package, and the new growth is often very different from normal tissue and may confuse the identification.

Bryophytes do not need to be pressed to prevent their wilting because soaking the dried specimen in water will restore it to its original form, and may even allow growth to re-continue. Lichens are changed very little on drying.

Bryophyte morphology
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2.12 Herbarium packets

Once moss and lichen specimens are dry they may be stored permanently in specially made herbarium packets. These should be made of good quality, 100% rag, 21 x 27 cm bond paper that will not yellow or become brittle. This paper is folded as shown in Figure 3. If the packets are folded around a 10 x 15 cm index card they will be stiffer and of uniform size. They may be stored in card index boxes or shoe boxes. Information may be written directly on the front of the envelope or on an herbarium label pasted onto it. The advantages of these packets over paper bags or commercial envelopes is that they can be opened flat for examination of the specimen.

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|TABLE OF CONTENTS |THE NAMES OF PLANTS |PLANT COLLECTING |PLANT IDENTIFICATION |REFERENCES|
|APPENDIX - THE MEANING OF SPECIFIC EPITHETS |APPENDIX - BIBLIOGRAPHY|

The Names of Plants - Guide to Plant Collection & Identification Jane M. Bowles 1996

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