|Themes > Science > Life Sciences > Collection & Preservation > Collection of Specimens > Collection and Field Preparation of Specimens|
*(contributed by J. R. Massey from Chapter 18 in Vascular Plant Systematics by A. E. Radford, W.C. Dickison, J. R. Massey and C. R. Bell, Harper and Row Publisher, 1974; used with permission of the authors)
Herbarium specimens are permanent records of a species (or population) as it occurred at a given time and place. The future value and use of any specimen is largely dependent on the care with which the collector selects, collects and prepares his spec imens. The following directions and suggestions on specimen preparation, field equipment and field records are given to assist collectors in preparing high quality herbarium specimens accompanied by adequate field notes.
Table of Contents
The specimens to be collected depend on the
objectives of the collector, and the types of material to be collected
will determine the techniques used, amount of material collected, and type
of field data recorded. The following suggestions can greatly ai d the
collector in getting maximum benefit of valuable field time.
II. Supplies and Equipment
III. Selection of Material.Vigorous, typical specimens are to be selected. Avoid insect damaged plants as well as exceptionally small or large plants. Specimens should be representative of the population, but should include the range of variation of the plants, not those that best fit the press. Roots, bulbs, and other underground parts should be carefully excavated and the dirt removed with care. In most cases flowering and/or fruiting materials are necessary for identification purposes. Many collectors prefer to add extra flowers and fruits to their collections when possible to avoid dissection of the specimen proper. Plants too large for a single sheet may be divided and pressed as a series of sheets (see discussion below). In collecting large herbs, shrubs and tr ees, different types of foliage, flowers and fruits should be collected from the same plant. Collect sufficient material to fill an herbarium sheet and still leave enough room for the label. Bark and wood samples are often desirable additions when colle cting woody plants. Proper identification of many plants depends on several different characteristics--some roots, others seeds or mature fruits, some flower color (which should be noted in the fieldbook).
The following suggestions which are largely adapted from DeWolf (1968), Fogg (1940), and Fosberg and Sachet (1965), and Smith (1971) are given to assist in the selection and collection of particular kinds of plants.
IV. Pressing Plant Specimens. V. Field Storage of Specimens
IV. Pressing Plant Specimens.A. Arranging and Preparing Specimens. After the specimens have been dug or cut they should be pressed as soon as possible (see V for information on field storage of fresh specimens). The care given a specimen in pressing will largely determine i ts future value. Specimens should be placed in a single fold of newsprint or other suitable absorbent lightweight paper. Plants too large to fit the 11" x 16" fold of paper may be bent into a "V", "N", or "M" figure. Bruise the stem before bending and it will be less apt to break. Specimens should not protrude from the fold of paper. Protruding parts will likely have to be removed when specimens are mounted. A specimen may be trimmed to reduce bulk and expose certain characters advantageously if suf ficient material (e.g., leaf petioles, branch bases, etc.) is left so that the pattern of branching, leaf arrangement, and other features are readily discernible. When pressing large plants are desirable make several sheets rather than a single sheet wit h a crumpled mass of material. Arrange specimens in such a way that some upper and some lower surfaces of the leaves are exposed. Spread flowers or inflorescences to show as many surfaces or views as possible. Section some flowers longitudinally and press flat to exhibit the inner parts and thereby reduce the need for dissection of the finished specimen.
V. Field Storage of SpecimensAlthough it is desirable to press collections immediately, it may not always be practical. Delicate materials should be pressed as soon as possible and other specimens properly sorted. Vascula, plastic bags, or rubberized bags can be used for storage if specimens are first wrapped in moistened paper. Specimens may be kept in good shape without spoilage in the containers if they are kept moist and not packed too tightly. Supersaturation with water or drying out will spoil specimens. The specimen bags should be kept as cool as possible and a conscious effort should be made to park a specimen-loaded vehicle in the shade on field trips.
Specimens are dipped, sprayed or brushed with these solutions and enclosed in airtight packages. For additional details consult Fosberg and Sachet (1965) and Lawrence (1951) and Smith (1971).
VI. Drying Field Collections.Plants should be placed in the press and the press closed and tightened. The faster the drying process the less difficulty with mold, mildew and loss of color. Plants should be sweated in the field press for 12-24 hours and the press opened. Any last ar rangement of the specimens must be made at this time and the wet driers hanged. For exceptional results driers should be changed at least three times during the first 48 hours. In many areas blotters may be dried in the sun (usually one hour is sufficie nt). If specimens are to be dried without artificial heat, blotters should be changed daily until specimens are dry. Automobile luggage carriers are excellent means of drying specimens provided ventilators with open ducts are used between the blotters.< BR> If artificial heat is used, there should be maximum airflow through the press. Never attempt to dry specimens in an oven. Use doublefaced corrugated cardboard or aluminum ventilators. A metal or wooden box with an open top which will accommodate a pre ss sideways (corrugations pointing up) and equipped with an electric heater with fan makes an excellent drying chamber. A collapsible drying frame (either a wooded box or metal frame with canvas skirt) may be used in the field and a camp stove ot lanter n used a heat source. Electric heating coils or light bulbs may also be used as heat sources but a fan should be installed either in or above the chamber. Special drying cabinets are sold but most lack sufficient ventilation for proper drying of speci mens.
VII. Data to Accompany Specimens.A. Field Notes. As mentioned earlier every collector should keep a field book. This is not simply a road log. Each species collected at a given place and time should be given a collection number. The best system is to use a chronological one b eginning with number one and continuing from there. Avoid elaborate numbering systems with prefixes and cryptic notations or abbreviations. Do not use the same number for any other collection. All duplicates or replicates should bear the same collectio n or collector's number. Although some abbreviations may be useful and efficient in the field, these should be fully written out when permanent labels are made from the field notes. A specimen without field data (at least locality and date) is of no sci entific value.
Data to be recorded in the field notebook should include collector's number (for reference), exact locality, approximate altitude, nature of the habitat (type of soil, moisture conditions, slope exposure, light conditions), associated species, and other p ertinent information. With reference to the plant proper, record those features which will not be evident from the pressed specimen (height, branching, depth of root system, odor, etc.) and those features which may be lost in drying; e.g., flower color. Flower color may best be determined by using a color chart. The more complete the field notes, the more complete the permanent label can be and the greater the information content of the apecimen. B. Permanent Label. The permanent label is the label affixed to the mounting sheet with a specimen. Information included in addition to the name of the plant and authority (e.g., Claytonia caroliniana Michaux) must come from the collector's field notebook. Do not abbreviate or use symbols.
Specimens are now used throughout the world and symbols and abbreviations are often difficult to translate. Be specific in giving localities. If local names are used, give some reference to a city, major highway, or easily located reference point. Mini mum data for labels should include date, locality, county, state, collector and collection number. Labels, unless done by offset printing, should be typewritten using a carbon ribbon or written in longhand using india or other permanent ink. Paper shoul d be of high rag content--preferably 100%. See sample label ( 3 X 5) given below.
VIII. Identification of CollectionsMaterials should be identified using the appropriate manuals, floras and monographs (see chapter 30). If it is necessary to have materials identified or verified by a specialist, one of the duplicates is sent with a label to the specialist. Generally th e specialist will keep the specimen unless he has agreed to do otherwise. In the event that a duplicate specimen is identified by someone else, the collector should enter the plant name on the label followed by the name of the specialist and date that the duplicate was determined; e.g.,